SILK-MOTHS.
These insects are in several respects interesting to us, more especially because they have varied largely at an early period of life, and the variations have been inherited at corresponding periods. As the value of the silk-moth depends entirely on the cocoon, every change in its structure and qualities has been carefully attended to, and races differing much in the cocoon, but hardly at all in the adult state, have been produced. With the races of most other domestic animals, the young resemble each other closely, whilst the adults differ much.
It would be useless, even if it were possible, to describe all the many kinds of silkworms. Several distinct species exist in India and China which produce useful silk, and some of these are capable of freely crossing with the common silk-moth, as has been recently ascertained in France. Captain Hutton[[65]] states that throughout the world at least six species have been domesticated; and he believes that the silk-moths reared in Europe belong to two or three species. This, however, is not the opinion of several capable judges who have particularly attended to the cultivation of this insect in France; and hardly accords with some facts presently to be given.
The common silk-moth (Bombyx mori) was brought to Constantinople in the sixth century, whence it was carried into Italy, and in 1494 into France.[[66]] Everything has been favourable for the variation of this insect. It is believed to have been domesticated in China as long ago as 2700 B.C. It has been kept under unnatural and diversified conditions of life, and has been transported into many countries. There is reason to believe that the nature of the food given to the caterpillar influences to a certain extent the character of the breed.[[67]] Disuse has apparently aided in checking the development of the wings. But the most important element in the production of the many now existing, much modified races, no doubt has been the close attention which has long been applied in many countries to every promising variation. The care taken in Europe in the selection of the best cocoons and moths for breeding is notorious,[[68]] and the production of eggs is followed as a distinct trade in parts of France. I have made inquiries through Dr. Falconer, and am assured that in India the natives are equally careful in the process of selection. In China the production of eggs is confined to certain favourable districts, and the raisers are precluded by law from producing silk, so that their whole attention may be necessarily given up to this one object.[[69]]
The following details on the differences between the several breeds are taken, when not stated to the contrary, from M. Robinet’s excellent work,[[70]] which bears every sign of care and large experience. The eggs in the different races vary in colour, in shape (being round, elliptic or oval), and in size. The eggs laid in June in the south of France, and in July in the central provinces, do not hatch until the following spring; and it is in vain, says M. Robinet, to expose them to a temperature gradually raised, in order that the caterpillar may be quickly developed. Yet occasionally, without any known cause, batches of eggs are produced, which immediately begin to undergo the proper changes, and are hatched in from twenty to thirty days. From these and some other analogous facts it may be concluded that the Trevoltini silkworms of Italy, of which the caterpillars are hatched in from fifteen to twenty days, do not necessarily form, as has been maintained, a distinct species. Although the breeds which live in temperate countries produce eggs which cannot be immediately hatched by artificial heat, yet when they are removed to and reared in a hot country they gradually acquire the character of quick development, as in the Trevoltini races.[[71]]
Caterpillars.—These vary greatly in size and colour. The skin is generally white, sometimes mottled with black or grey, and occasionally quite black. The colour, however, as M. Robinet asserts, is not constant, even in perfectly pure breeds; except in the race tigrée, so called from being marked with transverse black stripes. As the general colour of the caterpillar is not correlated with that of the silk,[[72]] this character is disregarded by cultivators, and has not been fixed by selection. Captain Hutton, in the paper before referred to, has argued with much force that the dark tiger-like marks, which so frequently appear during the later moults in the caterpillars of various breeds, are due to reversion; for the caterpillars of several allied wild species of Bombyx are marked and coloured in this manner. He separated some caterpillars with the tiger-like marks, and in the succeeding spring (pp. 149, 298) nearly all the caterpillars reared from them were dark-brindled, and the tints became still darker in the third generation. The moths reared from these caterpillars[[73]] also became darker, and resembled in colouring the wild B. huttoni. On this view of the tiger-like marks being due to reversion, the persistency with which they are transmitted is intelligible.
Several years ago Mrs. Whitby took great pains in breeding silkworms on a large scale, and she informed me that some of her caterpillars had dark eyebrows. This is probably the first step in reversion towards the tiger-like marks, and I was curious to know whether so trifling a character would be inherited. At my request she separated in 1848 twenty of these caterpillars, and having kept the moths separate, bred from them. Of the many caterpillars thus reared, “every one without exception had eyebrows, some darker and more decidedly marked than the others, but all had eyebrows more or less plainly visible.” Black caterpillars occasionally appear amongst those of the common kind, but in so variable a manner, that, according to M. Robinet, the same race will one year exclusively produce white caterpillars, and the next year many black ones; nevertheless, I have been informed by M. A. Bossi of Geneva, that, if these black caterpillars are separately bred from, they reproduce the same colour; but the cocoons and moths reared from them do not present any difference.
The caterpillar in Europe ordinarily moults four times before passing into the cocoon stage; but there are races “à trois mues,” and the Trevoltini race likewise moults only thrice. It might have been thought that so important a physiological difference would not have arisen under domestication; but M. Robinet[[74]] states that, on the one hand, ordinary caterpillars occasionally spin their cocoons after only three moults, and, on the other hand, “presque toutes les races à trois mues, que nous avons expérimentees, ont fait quatre mues à la seconde ou à la troisième année, ce qui semble prouver qu’il a suffi de les placer dans des conditions favorables pour leur rendre une faculté qu’elles avaient perdue sous des influences moins favorables.”
Cocoons.—The caterpillar in changing into the cocoon loses about 50 per cent of its weight; but the amount of loss differs in different breeds, and this is of importance to the cultivator. The cocoon in the different races presents characteristic differences; being large or small;—nearly spherical with no constriction, as in the Race de Loriol, or cylindrical, with either a deep or slight constriction in the middle; with the two ends, or with one end alone, more or less pointed. The silk varies in fineness and quality, and in being nearly white, but of two tints, or yellow. Generally the colour of the silk is not strictly inherited: but in the chapter on Selection I shall give a curious account how, in the course of sixty-five generations, the number of yellow cocoons in one breed has been reduced in France from one hundred to thirty-five in the thousand. According to Robinet, the white race, called Sina, by careful selection during the last seventy-five years, “est arrivée à un tel état de pureté, qu’on ne voit pas un seul cocon jaune dans des millions de cocons blancs.”[[75]] Cocoons are sometimes formed, as is well known, entirely destitute of silk, which yet produce moths; unfortunately Mrs. Whitby was prevented by an accident from ascertaining whether this character would prove hereditary.
Adult stage.—I can find no account of any constant difference in the moths of the most distinct races. Mrs. Whitby assured me that there was none in the several kinds bred by her; and I have received a similar statement from the eminent naturalist, M. de Quatrefages. Captain Hutton also says[[76]] that the moths of all kinds vary much in colour, but in nearly the same inconstant manner. Considering how much the cocoons in the several races differ, this fact is of interest, and may probably be accounted for on the same principle as the fluctuating variability of colour in the caterpillar, namely, that there has been no motive for selecting and perpetuating any particular variation.
The males of the wild Bombycidæ “fly swiftly in the day-time and evening, but the females are usually very sluggish and inactive.”[[77]] In several moths of this family the females have abortive wings, but no instance is known of the males being incapable of flight, for in this case the species could hardly have been perpetuated. In the silk-moth both sexes have imperfect, crumpled wings, and are incapable of flight; but still there is a trace of the characteristic difference in the two sexes; for though, on comparing a number of males and females, I could detect no difference in the development of their wings, yet I was assured by Mrs. Whitby that the males of the moths bred by her used their wings more than the females, and could flutter downwards, though never upwards. She also states that, when the females first emerge from the cocoon, their wings are less expanded than those of the male. The degree of imperfection, however, in the wings varies much in different races and under different circumstances. M. Quatrefages[[78]] says that he has seen a number of moths with their wings reduced to a third, fourth, or tenth part of their normal dimensions, and even to mere short straight stumps: “il me semble qu’il y a là un véritable arrêt de développement partiel.” On the other hand, he describes the female moths of the André Jean breed as having “leurs ailes larges et étalées. Un seul présente quelques courbures irrégulières et des plis anormaux.” As moths and butterflies of all kinds reared from wild caterpillars under confinement often have crippled wings, the same cause, whatever it may be, has probably acted on silk-moths, but the disuse of their wings during so many generations has, it may be suspected, likewise come into play.
The moths of many breeds fail to glue their eggs to the surface on which they are laid,[[79]] but this proceeds, according to Capt. Hutton,[[80]] merely from the glands of the ovipositor being weakened.
As with other long-domesticated animals, the instincts of the silk-moth have suffered. The caterpillars, when placed on a mulberry-tree, often commit the strange mistake of devouring the base of the leaf on which they are feeding, and consequently fall down; but they are capable, according to M. Robinet,[[81]] of again crawling up the trunk. Even this capacity sometimes fails, for M. Martins[[82]] placed some caterpillars on a tree, and those which fell were not able to remount and perished of hunger; they were even incapable of passing from leaf to leaf.
Some of the modifications which the silk-moth has undergone stand in correlation with one another. Thus, the eggs of the moths which produce white cocoons and of those which produce yellow cocoons differ slightly in tint. The abdominal feet, also, of the caterpillars which yield white cocoons are always white, whilst those which give yellow cocoons are invariably yellow.[[83]] We have seen that the caterpillars with dark tiger-like stripes produce moths which are more darkly shaded than other moths. It seems well established[[84]] that in France the caterpillars of the races which produce white silk, and certain black caterpillars, have resisted, better than other races, the disease which has recently devastated the silk-districts. Lastly, the races differ constitutionally, for some do not succeed so well under a temperate climate as others; and a damp soil does not equally injure all the races.[[85]]
From these various facts we learn that silk-moths, like the higher animals, vary greatly under long-continued domestication. We learn also the more important fact that variations may occur at various periods of life, and be inherited at a corresponding period. And finally we see that insects are amenable to the great principle of Selection.
REFERENCES
[1] ‘Poultry Chronicle,’ 1854, vol. ii. p. 91 and vol. i. p. 330.
[2] Dr. Turral, ‘Bull. Soc. d’Acclimat.,’ tom. vii., 1860, p. 541.
[3] Willughby’s ‘Ornithology,’ by Ray, p. 381. This breed is also figured by Albin in 1734 in his ‘Nat. Hist. of Birds,’ vol. ii. p. 86.
[4] F. Cuvier, in ‘Annales du Muséum,’ tom. ix. p. 128, says that moulting and incubation alone stops these ducks laying. Mr. B. P. Brent makes a similar remark in the ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.
[5] Rev. E. S. Dixon, ‘Ornamental and Domestic Poultry’ (1848), p. 117. Mr. B. P. Brent, in ‘Poultry Chronicle,’ vol. iii., 1855, p. 512.
[6] Crawfurd on the ‘Relation of Domesticated Animals to Civilisation,’ read before the Brit. Assoc. at Oxford, 1860.
[7] Dureau de La Malle, in ‘Annales des Sciences Nat.,’ tom. xvii. p. 164; and tom. xxi. p. 55. Rev. E. S. Dixon, ‘Ornamental Poultry,’ p. 118. Tame ducks were not known in Aristotle’s time, as remarked by Volz, in his ‘Beiträge zur Kulturgeschichte,’ 1852, s. 78.
[8] I quote this account from ‘Die Enten-und Schwanenzucht,’ Ulm 1828, s. 143. See Audubon’s ‘Ornithological Biography,’ vol. iii. p. 168, on the taming of ducks on the Mississippi. For the same fact in England, see Mr. Waterton in Loudon’s ‘Mag. of Nat. Hist.,’ vol. viii. 1835, p. 542; and Mr. St. John, ‘Wild Sports and Nat. Hist. of the Highlands,’ 1846, p. 129.
[9] Mr. E. Hewitt, in ‘Journal of Horticulture,’ 1862, p. 773; and 1863, p. 39.
[10] I have met with several statements on the fertility of the several breeds when crossed. Mr. Yarrell assured me that Call and common ducks are perfectly fertile together. I crossed Hook-billed and common ducks, and a Penguin and Labrador, and the crossed Ducks were quite fertile, though they were not bred inter se, so that the experiment was not fully tried. Some half-bred Penguins and Labradors were again crossed with Penguins, and subsequently bred by me inter se, and they were extremely fertile.
[11] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.
[12] ‘Journal of the Indian Archipelago,’ vol. v. p. 334.
[13] ‘The Zoologist,’ vols. vii, viii. (1849-1850), p. 2353.
[14] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.
[15] ‘Poultry Chronicle,’ vol. iii. 1855, p. 312. With respect to Rouens see ditto vol. i. 1854, p. 167.
[16] Col. Hawker’s ‘Instructions to young Sportsmen,’ quoted by Mr. Dixon in his ‘Ornamental Poultry,’ p. 125.
[17] ‘Cottage Gardener,’ April 9th, 1861.
[18] These hybrids have been described by M. Selys-Longchamps in the ‘Bulletins (tom. xii. No 10) Acad. Roy. de Bruxelles.’
[19] ‘Proc. Zoolog. Soc.,’ 1861, p. 261.
[20] ‘Ceylon,’ by Sir J. E. Tennent, 1859, vol. i. p. 485; also J. Crawfurd on the ‘Relation of Domest. Animals to Civilisation,’ read before Brit. Assoc. 1860. See also ‘Ornamental Poultry,’ by Rev. E. S. Dixon, 1848, p. 132. The goose figured on the Egyptian monuments seems to have been the Red goose of Egypt.
[21] Macgillivray’s ‘British Birds,’ vol. iv. p. 593.
[22] Mr. A. Strickland (‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. iii. 1859, p. 122) reared some young wild geese, and found them in habits and in all characters identical with the domestic goose.
[23] See also Hunter’s ‘Essays,’ edited by Owen, vol. ii. p. 322.
[24] Yarrell’s ‘British Birds,’ vol. iii. p. 142.
[25] L. Lloyd, ‘Scandinavian Adventures,’ 1854, vol. ii. p. 413, says that the wild goose lays from five to eight eggs, which is a much fewer number than that laid by our domestic goose.
[26] The Rev. L. Jenyns (Blomefield) seems first to have made this observation in his ‘British Animals.’ See also Yarrell, and Dixon in his ‘Ornamental Poultry’ (p. 139), and ‘Gardener’s Chronicle,’ 1857, p. 45.
[27] Mr. Bartlet exhibited the head and neck of a bird thus characterised before the Zoological Soc., Feb. 1860.
[28] W. Thompson, ‘Natural Hist. of Ireland,’ 1851, vol. iii. p. 31. The Rev. E. S. Dixon gave me some information on the varying colour of the beak and legs.
[29] Mr. A. Strickland, in ‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. iii., 1859, p. 122.
[30] ‘Poultry Chronicle,’ vol. i., 1854, p. 498; vol. iii. p. 210.
[31] ‘The Cottage Gardener.’ Sept. 4th, 1860, p. 348.
[32] ‘L’Hist. de la Nature des Oiseaux,’ par P. Belon, 1555, p. 156. With respect to the livers of white geese being preferred by the Romans see Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’ tom. iii. p. 58.
[33] Mr. Sclater on the black-shouldered peacock of Latham, ‘Proc. Zoolog. Soc.,’ April 24th, 1860. Mr. Swinhoe at one time believed, (‘Ibis,’ July, 1868) that this kind of peafowl was found wild in Cochin China, but he has since informed me that he feels very doubtful on this head.
[34] ‘Proc. Zoolog. Soc.,’ April 14th, 1835.
[35] ‘The Field,’ May 6th, 1871. I am much indebted to Mr. Canning for information with respect to his birds.
[36] ‘Proc. Zoolog. Soc.,’ April 8th, 1856, p. 61. Prof. Baird believes (as quoted in Tegetmeier’s ‘Poultry Book,’ 1866, p. 269) that our turkeys are descended from a West Indian species now extinct. But besides the improbability of a bird having long ago become extinct in these large and luxuriant islands, it appears (as we shall presently see) that the turkey degenerates in India, and this fact indicates that it was not aboriginally an inhabitant of the lowlands of the tropics.
[37] Audubon’s ‘Ornithological Biography,’ vol. i., 1831, pp. 4-13; and ‘Naturalist’s Library,’ vol. xiv., Birds, p. 138.
[38] F. Michaux, ‘Travels in N. America,’ 1802, Eng. translat., p. 217.
[39] ‘Ornamental Poetry,’ by the Rev. E. S. Dixon, 1848, p. 34.
[40] Bechstein, ‘Naturgesch. Deutschlands,’ B. iii., 1793, s. 309.
[41] Mr. Bartlett in ‘Land and Water,’ Oct. 31st, 1868, p. 233; and Mr. Tegetmeier in the ‘Field,’ July 17th, 1869, p. 46.
[42] ‘Gardener’s Chronicle,’ 1852, p. 699.
[43] E. Blyth, in ‘Annals and Mag. of Nat. Hist.,’ 1847, vol. xx. p. 391.
[44] Roulin makes this remark in ‘Mém. de divers Savans, l’Acad. des Sciences,’ tom. vi., 1835, p. 349. Mr. Hill, of Spanish Town, in a letter to me, describes five varieties of the Guinea fowl in Jamaica. I have seen singular pale-coloured varieties imported from Barbadoes and Demerara.
[45] For St. Domingo, see M. A. Salle, in ‘Proc. Zoolog. Soc.’ 1857, p. 236. Mr. Hill remarks to me, in his letter, on the colour of the legs of the feral birds in Jamaica.
[46] Mr. B. P. Brent, ‘The Canary, British Finches,’ etc., pp. 21, 30.
[47] ‘Cottage Gardener,’ Dec. 11th, 1855, p. 184: an account is here given of all the varieties. For many measurements of the wild birds, see Mr. E. Vernon Harcourt, ibid., Dec. 25th, 1855, p. 223.
[48] Bechstein, ‘Naturgesch. der Stubenvögel,’ 1840, s. 243; see s. 252 on the inherited song of Canary-birds. With respect to their baldness see also W. Kidd’s ‘Treatise on Song-Birds.’
[49] W. Kidd’s ‘Treatise on Song-Birds,’ p. 18.
[50] The ‘Indian Field,’ 1858, p. 255.
[51] Yarrell’s ‘British Fishes,’ vol. i. p. 319.
[52] Mr. Blyth in the ‘Indian Field,’ 1858, p. 255.
[53] W. F. Mayers, ‘Chinese Notes and Queries,’ Aug. 1868, p. 123.
[54] ‘Proc. Zoolog. Soc.’ May 25, 1842.)
[55] Yarrell’s ‘British Fishes,’ vol. i. p. 319.
[56] ‘Dict. Class. d’Hist. Nat.,’ tom. v. p. 276.
[57] ‘Observations in Nat. Hist.,’ 1846, p. 211. Dr. Gray has described, in ‘Annals and Mag. of Nat. Hist.,’ 1860, p. 151 a nearly similar variety but destitute of a dorsal fin.
[58] ‘De l’Espèce,’ 1859, p. 459. With respect to the bees of Burgundy see M. Gerard, art. ‘Espèce,’ in ‘Dict. Univers. d’Hist. Nat.’
[59] See a discussion on this subject, in answer to a question of mine, in ‘Journal of Horticulture,’ 1862, pp. 225-242; also Mr. Bevan Fox, in ditto, 1862, p. 284.
[60] This excellent observer may be implicitly trusted; see ‘Journal of Horticulture,’ July 14th, 1863, p. 39.
[61] ‘Journal of Horticulture,’ Sept. 9th, 1862, p. 463; see also Herr Kleine on same subject (Nov. 11th, p. 643, who sums up, that, though there is some variability in colour, no constant or perceptible differences can be detected in the bees of Germany.
[62] Mr. Woodbury has published several such accounts in ‘Journal of Horticulture,’ 1861 and 1862.
[63] ‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. xi. p. 339.
[64] ‘The Cottage Gardener,’ May 1860, p. 110; and ditto in ‘Journal of Hort.,’ 1862, p. 242.
[65] ‘Transact. Entomolog. Soc.’ 3rd series, vol. iii. pp. 143-173 and pp. 295-331.
[66] Godron, ‘De l’Espèce,’ 1859, tom. i. p. 460. The antiquity of the silkworm in China is given on the authority of Stanislas Julien.
[67] See the remarks of Prof. Westwood, Gen. Hearsey and others at the meeting of the Entomolog. Soc. of London, July, 1861.
[68] See for instance M. A. de Quatrefages’ ‘Études sur les Maladies actuelles du Ver à Soie,’ 1859, p. 101.
[69] My authorities for the statements will be given in the chapter on Selection.
[70] ‘Manuel de l’Éducateur de Vers à Soie,’ 1848.
[71] Robinet, ibid., pp. 12, 318. I may add that the eggs of N. American silkworms taken to the Sandwich Islands produced moths at very irregular periods; and the moths thus raised yielded eggs which were even worse in this respect. Some were hatched in ten days, and others not until after the lapse of many months. No doubt a regular early character would ultimately have been acquired. See review in ‘Athenæum,’ 1844, p. 329, of J. Jarves’ ‘Scenes in the Sandwich Islands.’
[72] ‘The Art of rearing Silk-worms,’ translated from Count Dandolo, 1825, p. 23.
[73] ‘Transact. Ent. Soc.,’ ut supra, pp. 153, 308.
[74] Robinet, ibid., p. 317.
[75] Robinet, ibid., pp. 306-317.
[76] ‘Transact. Ent. Soc.,’ ut supra, p. 317.
[77] Stephen’s Illustrations, ‘Haustellata,’ vol. ii. p. 35. See also Capt. Hutton, ‘Transact. Ent. Soc.,’ ibid., p. 152.
[78] ‘Études sur les Maladies du Ver à Soie,’ 1859, pp. 304, 209.
[79] Quatrefages, ‘Études,’ etc., p. 214.
[80] ‘Transact. Ent. Soc.,’ ut supra, p. 151.
[81] ‘Manuel de l’Educateur,’ etc., p. 26.
[82] Godron, ‘De l’Espèce,’ p. 462.
[83] Quatrefages, ‘Études,’ etc., pp. 12, 209, 214.
[84] Robinet, ‘Manuel,’ etc., p. 303.
[85] Robinet, ibid., p. 15.
CHAPTER IX.
CULTIVATED PLANTS: CEREAL AND CULINARY PLANTS.
PRELIMINARY REMARKS ON THE NUMBER AND PARENTAGE OF CULTIVATED PLANTS—FIRST STEPS IN CULTIVATION—GEOGRAPHICAL DISTRIBUTION OF CULTIVATED PLANTS.
CEREALIA. DOUBTS ON THE NUMBER OF SPECIES—WHEAT: VARIETIES OF—INDIVIDUAL VARIABILITY—CHANGED HABITS—SELECTION—ANCIENT HISTORY OF THE VARIETIES—MAIZE: GREAT VARIATION OF—DIRECT ACTION OF CLIMATE ON.
CULINARY PLANTS.—CABBAGES: VARIETIES OF, IN FOLIAGE AND STEMS, BUT NOT IN OTHER PARTS—PARENTAGE OF—OTHER SPECIES OF BRASSICA—PEAS: AMOUNT OF DIFFERENCE IN THE SEVERAL KINDS, CHIEFLY IN THE PODS AND SEED—SOME VARIETIES CONSTANT, SOME HIGHLY VARIABLE—DO NOT INTERCROSS—BEANS—POTATOES: NUMEROUS VARIETIES OF—DIFFERING LITTLE EXCEPT IN THE TUBERS—CHARACTERS INHERITED.
I shall not enter into so much detail on the variability of cultivated plants, as in the case of domesticated animals. The subject is involved in much difficulty. Botanists have generally neglected cultivated varieties, as beneath their notice. In several cases the wild prototype is unknown or doubtfully known; and in other cases it is hardly possible to distinguish between escaped seedlings and truly wild plants, so that there is no safe standard of comparison by which to judge of any supposed amount of change. Not a few botanists believe that several of our anciently cultivated plants have become so profoundly modified that it is not possible now to recognise their aboriginal parent-forms. Equally perplexing are the doubts whether some of them are descended from one species, or from several inextricably commingled by crossing and variation. Variations often pass into, and cannot be distinguished from, monstrosities; and monstrosities are of little significance for our purpose. Many varieties are propagated solely by grafts, buds, layers, bulbs, etc., and frequently it is not known how far their peculiarities can be transmitted by seminal generation. Nevertheless, some facts of value can be gleaned: and other facts will hereafter be incidentally given. One chief object in the two following chapters is to show how many characters in our cultivated plants have become variable.
Before entering on details a few general remarks on the origin of cultivated plants may be introduced. M. Alph. De Candolle[[1]] in an admirable discussion on this subject, in which he displays a wonderful amount of knowledge, gives a list of 157 of the most useful cultivated plants. Of these he believes that 85 are almost certainly known in their wild state; but on this head other competent judges[[2]] entertain great doubts. Of 40 of them, the origin is admitted by M. De Candolle to be doubtful, either from a certain amount of dissimilarity which they present when compared with their nearest allies in a wild state, or from the probability of the latter not being truly wild plants, but seedlings escaped from culture. Of the entire 157, 32 alone are ranked by M. De Candolle as quite unknown in their aboriginal condition. But it should be observed that he does not include in his list several plants which present ill-defined characters, namely, the various forms of pumpkins, millet, sorghum, kidney-bean, dolichos, capsicum, and indigo. Nor does he include flowers; and several of the more anciently cultivated flowers, such as certain roses, the common Imperial lily, the tuberose, and even the lilac, are said[[3]] not to be known in the wild state.
From the relative numbers above given, and from other arguments of much weight, M. De Candolle concludes that plants have rarely been so much modified by culture that they cannot be identified with their wild prototypes. But on this view, considering that savages probably would not have chosen rare plants for cultivation, that useful plants are generally conspicuous, and that they could not have been the inhabitants of deserts or of remote and recently discovered islands, it appears strange to me that so many of our cultivated plants should be still unknown or only doubtfully known in the wild state. If, on the other hand, many of these plants have been profoundly modified by culture, the difficulty disappears. The difficulty would also be removed if they have been exterminated during the progress of civilisation; but M. De Candolle has shown that this probably has seldom occurred. As soon as a plant was cultivated in any country, the half-civilised inhabitants would no longer have need to search the whole surface of the land for it, and thus lead to its extirpation; and even if this did occur during a famine, dormant seeds would be left in the ground. In tropical countries the wild luxuriance of nature, as was long ago remarked by Humboldt, overpowers the feeble efforts of man. In anciently civilised temperate countries, where the whole face of the land has been greatly changed, it can hardly be doubted that some plants have become extinct; nevertheless De Candolle has shown that all the plants historically known to have been first cultivated in Europe still exist here in the wild state.
MM. Loiseleur-Deslongchamps[[4]] and De Candolle have remarked that our cultivated plants, more especially the cereals, must originally have existed in nearly their present state; for otherwise they would not have been noticed and valued as objects of food. But these authors apparently have not considered the many accounts given by travellers of the wretched food collected by savages. I have read an account of the savages of Australia cooking, during a dearth, many vegetables in various ways, in the hopes of rendering them innocuous and more nutritious. Dr. Hooker found the half-starved inhabitants of a village in Sikhim suffering greatly from having eaten arum-roots,[[5]] which they had pounded and left for several days to ferment, so as partially to destroy their poisonous nature; and he adds that they cooked and ate many other deleterious plants. Sir Andrew Smith informs me that in South Africa a large number of fruits and succulent leaves, and especially roots, are used in times of scarcity. The natives, indeed, know the properties of a long catalogue of plants, some having been found during famines to be eatable, others injurious to health, or even destructive to life. He met a party of Baquanas who, having been expelled by the conquering Zulus, had lived for years on any roots or leaves which afforded some little nutriment and distended their stomachs, so as to relieve the pangs of hunger. They looked like walking skeletons, and suffered fearfully from constipation. Sir Andrew Smith also informs me that on such occasions the natives observe as a guide for themselves, what the wild animals, especially baboons and monkeys, eat.
From innumerable experiments made through dire necessity by the savages of every land, with the results handed down by tradition, the nutritious, stimulating, and medicinal properties of the most unpromising plants were probably first discovered. It appears, for instance, at first an inexplicable fact that untutored man, in three distant quarters of the world, should have discovered, amongst a host of native plants, that the leaves of the tea-plant and mattee, and the berries of the coffee, all included a stimulating and nutritious essence, now known to be chemically the same. We can also see that savages suffering from severe constipation would naturally observe whether any of the roots which they devoured acted as aperients. We probably owe our knowledge of the uses of almost all plants to man having originally existed in a barbarous state, and having been often compelled by severe want to try as food almost everything which he could chew and swallow.
From what we know of the habits of savages in many quarters of the world, there is no reason to suppose that our cereal plants originally existed in their present state so valuable to man. Let us look to one continent alone, namely, Africa: Barth[[6]] states that the slaves over a large part of the central region regularly collect the seeds of a wild grass, the Pennisetum distichum; in another district he saw women collecting the seeds of a Poa by swinging a sort of basket through the rich meadow-land. Near Tete, Livingstone observed the natives collecting the seeds of a wild grass, and farther south, as Andersson informs me, the natives largely use the seed of a grass of about the size of canary-seed, which they boil in water. They eat also the roots of certain reeds, and every one has read of the Bushmen prowling about and digging up with a fire-hardened stake various roots. Similar facts with respect to the collection of seeds of wild grasses in other parts of the world could be given.[[7]]
Accustomed as we are to our excellent vegetables and luscious fruits, we can hardly persuade ourselves that the stringy roots of the wild carrot and parsnip, or the little shoots of the wild asparagus, or crabs, sloes, etc., should ever have been valued; yet, from what we know of the habits of Australian and South African savages, we need feel no doubt on this head. The inhabitants of Switzerland during the Stone-period largely collected wild crabs, sloes, bullaces, hips of roses, elderberries, beechmast, and other wild berries and fruit.[[8]] Jemmy Button, a Fuegian on board the ‘Beagle,’ remarked to me that the poor and acid black-currants of Tierra del Fuego were too sweet for his taste.
The savage inhabitants of each land, having found out by many and hard trials what plants were useful, or could be rendered useful by various cooking processes, would after a time take the first step in cultivation by planting them near their usual abodes. Livingstone[[9]] states that the savage Batokas sometimes left wild fruit-trees standing in their gardens, and occasionally even planted them, “a practice seen nowhere else amongst the natives.” But Du Chaillu saw a palm and some other wild fruit-trees which had been planted; and these trees were considered private property. The next step in cultivation, and this would require but little forethought, would be to sow the seeds of useful plants; and as the soil near the hovels of the natives[[10]] would often be in some degree manured, improved varieties would sooner or later arise. Or a wild and unusually good variety of a native plant might attract the attention of some wise old savage; and he would transplant it, or sow its seed. That superior varieties of wild fruit-trees occasionally are found is certain, as in the case of the American species of hawthorns, plums, cherries, grapes, and hickories, specified by Professor Asa Gray.[[11]] Downing also refers to certain wild varieties of the hickory, as being “of much larger size and finer flavour than the common species.” I have referred to American fruit-trees, because we are not in this case troubled with doubts whether or not the varieties are seedlings which have escaped from cultivation. Transplanting any superior variety, or sowing its seeds, hardly implies more forethought than might be expected at an early and rude period of civilisation. Even the Australian barbarians “have a law that no plant bearing seeds is to be dug up after it has flowered;” and Sir G. Grey[[12]] never saw this law, evidently framed for the preservation of the plant, violated. We see the same spirit in the superstitious belief of the Fuegians, that killing water-fowl whilst very young will be followed by “much rain, snow, blow much.”[[13]] I may add, as showing forethought in the lowest barbarians, that the Fuegians when they find a stranded whale bury large portions in the sand, and during the often-recurrent famines travel from great distances for the remnants of the half-putrid mass.
It has often been remarked[[1]] that we do not owe a single useful plant to Australia or the Cape of Good Hope, countries abounding to an unparalleled degree with endemic species,—or to New Zealand, or to America south of the Plata; and, according to some authors, not to America northward of Mexico. I do not believe that any edible or valuable plant, except the canary-grass, has been derived from an oceanic or uninhabited island. If nearly all our useful plants, natives of Europe; Asia, and South America, had originally existed in their present condition, the complete absence of similarly useful plants in the great countries just named would be indeed a surprising fact. But if these plants have been so greatly modified and improved by culture as no longer closely to resemble any natural species, we can understand why the above-named countries have given us no useful plants, for they were either inhabited by men who did not cultivate the ground at all, as in Australia and the Cape of Good Hope, or who cultivated it very imperfectly, as in some parts of America. These countries do yield plants which are useful to savage man; and Dr. Hooker[[15]] enumerates no less than 107 such species in Australia alone; but these plants have not been improved, and consequently cannot compete with those which have been cultivated and improved during thousands of years in the civilised world.
The case of New Zealand, to which fine island we as yet owe no widely cultivated plant, may seem opposed to this view; for, when first discovered, the natives cultivated several plants; but all inquirers believe, in accordance with the traditions of the natives, that the early Polynesian colonists brought with them seeds and roots, as well as the dog, which had been wisely preserved during their long voyage. The Polynesians are so frequently lost on the ocean that this degree of prudence would occur to any wandering party: hence the early colonists of New Zealand, like the later European colonists, would not have had any strong inducement to cultivate the aboriginal plants. According to De Candolle we owe thirty-three useful plants to Mexico, Peru, and Chile; nor is this surprising when we remember the civilised state of the inhabitants, as shown by the fact of their having practised artificial irrigation and made tunnels through hard rocks without the use of iron or gunpowder, and who, as we shall see in a future chapter, fully recognised, as far as animals were concerned, and therefore probably in the case of plants, the important principle of selection. We owe some plants to Brazil; and the early voyagers, namely, Vespucius and Cabral, describe the country as thickly peopled and cultivated. In North America[[16]] the natives cultivated maize, pumpkins, gourds, beans, and peas, “all different from ours,” and tobacco; and we are hardly justified in assuming that none of our present plants are descended from these North American forms. Had North America been civilised for as long a period, and as thickly peopled, as Asia or Europe, it is probable that the native vines, walnuts, mulberries, crabs, and plums, would have given rise, after a long course of cultivation, to a multitude of varieties, some extremely different from their parent-stocks; and escaped seedlings would have caused in the New, as in the Old World, much perplexity with respect to their specific distinctness and parentage.’[[17]]
Cerealia.—I will now enter on details. The cereals cultivated in Europe consist of four genera—wheat, rye, barley, and oats. Of wheat the best modern authorities[[18]] make four or five, or even seven distinct species; of rye, one; of barley, three; and of oats, two, three, or four species. So that altogether our cereals are ranked by different authors under from ten to fifteen distinct species. These have given rise to a multitude of varieties. It is a remarkable fact that botanists are not universally agreed on the aboriginal parent-form of any one cereal plant. For instance, a high authority writes in 1855,[[19]] “We ourselves have no hesitation in stating our conviction, as the result of all the most reliable evidence, that none of these Cerealia exist, or have existed, truly wild in their present state, but that all are cultivated varieties of species now growing in great abundance in S. Europe or W. Asia.” On the other hand, Alph. De Candolle[[20]] has adduced abundant evidence that common wheat (Triticum vulgare) has been found wild in various parts of Asia, where it is not likely to have escaped from cultivation: and there is some force in M. Godron’s remark, that, supposing these plants to be escaped seedlings,[[21]] as they have propagated themselves in a wild state for several generations, their continued resemblance to cultivated wheat renders it probable that the latter has retained its aboriginal character. But the strong tendency to inheritance, which most of the varieties of wheat evince, as we shall presently see, is here greatly undervalued. Much weight must also be attributed to a remark by Professor Hildebrand[[22]] that when the seeds or fruit of cultivated plants possess qualities disadvantageous to them as a means of distribution, we may feel almost sure that they no longer retain their aboriginal condition. On the other hand, M. De Candolle insists strongly on the frequent occurrence in the Austrian dominions of rye and of one kind of oats in an apparently wild condition. With the exception of these two cases, which however are rather doubtful, and with the exception of two forms of wheat and one of barley, which he believes to have been found truly wild, M. De Candolle does not seem fully satisfied with the other reported discoveries of the parent-forms of our other cereals. With respect to oats, according to Mr. Buckmann,[[23]] the wild English Avena fatua can be converted by a few years of careful cultivation and selection into forms almost identical with two very distinct cultivated races. The whole subject of the origin and specific distinctness of the various cereal plants is a most difficult one; but we shall perhaps be able to judge a little better after considering the amount of variation which wheat has undergone.
Metzger describes seven species of wheat, Godron refers to five, and De Candolle to only four. It is not improbable that, besides the kinds known in Europe, other strongly characterised forms exist in the more distant parts of the world; for Loiseleur-Deslongchamps[[24]] speaks of three new species or varieties, sent to Europe in 1822 from Chinese Mongolia, which he considers as being there indigenous. Moorcroft[[25]] also speaks of Hasora wheat in Ladakh as very peculiar. If those botanists are right who believe that at least seven species of wheat originally existed, then the amount of variation in any important character which wheat has undergone under cultivation has been slight; but if only four or a lesser number of species originally existed, then it is evident that varieties have arisen so strongly marked, that they have been considered by capable judges as specifically distinct. But the impossibility of deciding which forms ought to be ranked as species and which as varieties, makes it useless to specify in detail the differences between the various kinds of wheat. Speaking generally, the organs of vegetation differ little;[[26]] but some kinds grow close and upright, whilst others spread and trail along the ground. The straw differs in being more or less hollow, and in quality. The ears[[27]] differ in colour and in shape, being quadrangular, compressed, or nearly cylindrical; and the florets differ in their approximation to each other, in their pubescence, and in being more or less elongated. The presence or absence of barbs is a conspicuous difference, and in certain Gramineæ serves even as a generic character;[[28]] although, as remarked by Godron,[[29]] the presence of barbs is variable in certain wild grasses, and especially in those such as Bromus secalinus and Lolium temulentum, which habitually grow mingled with our cereal crops, and which have thus unintentionally been exposed to culture. The grains differ in size, weight, and colour; in being more or less downy at one end, in being smooth or wrinkled, in being either nearly globular, oval, or elongated; and finally in internal texture, being tender or hard, or even almost horny, and in the proportion of gluten which they contain.
Nearly all the races or species of wheat vary, as Godron[[30]] has remarked, in an exactly parallel manner,—in the seed being downy or glabrous, and in colour,—and in the florets being barbed or not barbed, etc. Those who believe that all the kinds are descended from a single wild species may account for this parallel variation by the inheritance of a similar constitution, and a consequent tendency to vary in the same manner; and those who believe in the general theory of descent with modification may extend this view to the several species of wheat, if such ever existed in a state of nature.
Although few of the varieties of wheat present any conspicuous difference, their number is great. Dalbret cultivated during thirty years from 150 to 160 kinds, and excepting in the quality of the grain they all kept true; Colonel Le Couteur possessed upwards of 150, and Philippar 322 varieties.[[31]] As wheat is an annual, we thus see how strictly many trifling differences in character are inherited through many generations. Colonel Le Couteur insists strongly on this same fact. In his persevering and successful attempts to raise new varieties, he found that there was only one “secure mode to ensure the growth of pure sorts, namely, to grow them from single grains or from single ears, and to follow up the plan by afterwards sowing only the produce of the most productive so as to form a stock.” But Major Hallett[[32]] has gone much farther, and by the continued selection of plants from the grains of the same ear, during successive generations, has made his ‘Pedigree in Wheat’ (and other cereals) now famous in many quarters of the world. The great amount of variability in the plants of the same variety is another interesting point, which would never have been detected except by an eye long practised to the work; thus Colonel Le Couteur relates[[33]] that in a field of his own wheat, which he considered at least as pure as that of any of his neighbours, Professor La Gasca found twenty-three sorts; and Professor Henslow has observed similar facts. Besides such individual variations, forms sufficiently well marked to be valued and to become widely cultivated sometimes suddenly appear: thus Mr. Shirreff has had the good fortune to raise in his lifetime seven new varieties, which are now extensively grown in many parts of Britain.[[34]]
As in the case of many other plants, some varieties, both old and new, are far more constant in character than others. Colonel Le Couteur was forced to reject some of his new sub-varieties, which he suspected had been produced from a cross, as incorrigibly sportive. On the other hand Major Hallett[[35]] has shown how wonderfully constant some varieties are, although not ancient ones, and although cultivated in various countries. With respect to the tendency to vary, Metzger[[36]] gives from his own experience some interesting facts: he describes three Spanish sub-varieties, more especially one known to be constant in Spain, which in Germany assumed their proper character only during hot summers; another variety kept true only in good land, but after having been cultivated for twenty-five years became more constant. He mentions two other sub-varieties which were at first inconstant, but subsequently became, apparently without any selection, accustomed to their new homes, and retained their proper character. These facts show what small changes in the conditions of life cause variability, and they further show that a variety may become habituated to new conditions. One is at first inclined to conclude with Loiseleur-Deslongchamps, that wheat cultivated in the same country is exposed to remarkably uniform conditions; but manures differ, seed is taken from one soil to another, and, what is far more important, the plants are exposed as little as possible to struggle with other plants, and are thus enabled to exist under diversified conditions. In a state of nature each plant is confined to that particular station and kind of nutriment which it can seize from the other plants by which it is surrounded.
Wheat quickly assumes new habits of life. The summer and winter kinds were classed by Linnæus as distinct species; but M. Monnier[[37]] has proved that the difference between them is only temporary. He sowed winter-wheat in spring, and out of one hundred plants four alone produced ripe seeds; these were sown and resown, and in three years plants were reared which ripened all their seed. Conversely, nearly all the plants raised from summer-wheat, which was sown in autumn, perished from frost; but a few were saved and produced seed, and in three years this summer-variety was converted into a winter-variety. Hence it is not surprising that wheat soon becomes to a certain extent acclimatised, and that seed brought from distant countries and sown in Europe vegetates at first, or even for a considerable period,[[38]] differently from our European varieties. In Canada the first settlers, according to Kalm,[[39]] found their winters too severe for winter-wheat brought from France, and their summers often too short for summer-wheat; and they thought that their country was useless for corn crops until they procured summer-wheat from the northern parts of Europe, which succeeded well. It is notorious that the proportion of gluten differs much under different climates. The weight of the grain is also quickly affected by climate: Loiseleur-Deslongchamps[[40]] sowed near Paris 54 varieties, obtained from the South of France and from the Black Sea, and 52 of these yielded seed from 10 to 40 per cent heavier than the parent-seed. He then sent these heavier grains back to the South of France, but there they immediately yielded lighter seed.
All those who have closely attended to the subject insist on the close adaptation of numerous varieties of wheat to various soils and climates even within the same country; thus Colonel Le Couteur[[41]] says, “It is the suitableness of each sort to each soil that will enable the farmer to pay his rent by sowing one variety, where he would be unable to do so by attempting to grow another of a seemingly better sort.” This may be in part due to each kind becoming habituated to its conditions of life, as Metzger has shown certainly occurs, but it is probably in main part due to innate differences between the several varieties.
Much has been written on the deterioration of wheat; that the quality of the flour, size of grain, time of flowering, and hardness, may be modified by climate and soil, seems nearly certain; but that the whole body of any one sub-variety ever becomes changed into another and distinct sub-variety, there is no reason to believe. What apparently does take place, according to Le Couteur,[[42]] is, that some one sub-variety out of the many which may always be detected in the same field is more prolific than the others, and gradually supplants the variety which was first sown.
With respect to the natural crossing of distinct varieties the evidence is conflicting, but preponderates against its frequent occurrence. Many authors maintain that impregnation takes place in the closed flower, but I am sure from my own observation that this is not the case, at least with those varieties to which I have attended. But as I shall have to discuss this subject in another work, it may be here passed over.
In conclusion, all authors admit that numerous varieties of wheat have arisen; but their differences are unimportant, unless, indeed, some of the so-called species are ranked as varieties. Those who believe that from four to seven wild species of Triticum originally existed in nearly the same condition as at present, rest their belief chiefly on the great antiquity of the several forms.[[43]] It is an important fact, which we have recently learnt from the admirable researches of Heer,[[44]] that the inhabitants of Switzerland, even so early as the Neolithic period, cultivated no less than ten cereal plants, namely, five kinds of wheat, of which at least four are commonly looked at as distinct species, three kinds of barley, a panicum, and a setaria. If it could be shown that at the earliest dawn of agriculture five kinds of wheat and three of barley had been cultivated, we should of course be compelled to look at these forms as distinct species. But, as Heer has remarked, agriculture even at the Neolithic period, had already made considerable progress; for, besides the cereals, peas, poppies, flax, and apparently apples, were cultivated. It may also be inferred, from one variety of wheat being the so called Egyptian, and from what is known of the native country of the panicum and setaria, as well as from the nature of the weeds which then grew mingled with the crops, that the lake-inhabitants either still kept up commercial intercourse with some southern people or had originally proceeded as colonists from the South.
Loiseleur-Deslongchamps[[45]] has argued that, if our cereal plants have been greatly modified by cultivation, the weeds which habitually grow mingled with them would have been equally modified. But this argument shows how completely the principle of selection has been overlooked. That such weeds have not varied, or at least do not vary now in any extreme degree, is the opinion of Mr. H. C. Watson and Professor Asa Gray, as they inform me; but who will pretend to say that they do not vary as much as the individual plants of the same sub-variety of wheat? We have already seen that pure varieties of wheat, cultivated in the same field, offer many slight variations, which can be selected and separately propagated; and that occasionally more strongly pronounced variations appear, which, as Mr. Shirreff has proved, are well worthy of extensive cultivation. Not until equal attention be paid to the variability and selection of weeds, can the argument from their constancy under unintentional culture be of any value. In accordance with the principles of selection we can understand how it is that in the several cultivated varieties of wheat the organs of vegetation differ so little; for if a plant with peculiar leaves appeared, it would be neglected unless the grains of corn were at the same time superior in quality or size. the selection of seed-corn was strongly recommended[[46]] in ancient times by Columella and Celsus; and as Virgil says,—
“I’ve seen the largest seeds, tho’ view’d with care,
Degenerate, unless th’ industrious hand
Did yearly cull the largest.”
But whether in ancient times selection was methodically pursued we may well doubt, when we hear how laborious the work has been found by Le Coutour and Hallett. Although the principle of selection is so important, yet the little which man has effected, by incessant efforts[[47]] during thousands of years, in rendering the plants more productive or the grains more nutritious than they were in the time of the old Egyptians, would seem to speak strongly against its efficacy. But we must not forget that at each successive period the state of agriculture and the quantity of manure supplied to the land will have determined the maximum degree of productiveness; for it would be impossible to cultivate a highly productive variety, unless the land contained a sufficient supply of the necessary chemical elements.
We now know that man was sufficiently civilised to cultivate the ground at an immensely remote period; so that wheat might have been improved long ago up to that standard of excellence which was possible under the then existing state of agriculture. One small class of facts supports this view of the slow and gradual improvement of our cereals. In the most ancient lake-habitations of Switzerland, when men employed only flint-tools, the most extensively cultivated wheat was a peculiar kind, with remarkably small ears and grains.[[48]] “Whilst the grains of the modern forms are in section from seven to eight millimetres in length, the larger grains from the lake-habitations are six, seldom seven, and the smaller ones only four. The ear is thus much narrower, and the spikelets stand out more horizontally, than in our present forms.” So again with barley, the most ancient and most extensively cultivated kind had small ears, and the grains were “smaller, shorter, and nearer to each other, than in that now grown; without the husk they were 2½ lines long, and scarcely 1½ broad, whilst those now grown have a length of three lines, and almost the same in breadth.”[[49]] These small-grained varieties of wheat and barley are believed by Heer to be the parent-forms of certain existing allied varieties, which have supplanted their early progenitors.
Heer gives an interesting account of the first appearance and final disappearance of the several plants which were cultivated in greater or less abundance in Switzerland during former successive periods, and which generally differed more or less from our existing varieties. The peculiar small-eared and small-grained wheat, already alluded to, was the commonest kind during the Stone period; it lasted down to the Helvetico-Roman age, and then became extinct. A second kind was rare at first, but afterwards became more frequent. A third, the Egyptian wheat (T. turgidum), does not agree exactly with any existing variety, and was rare during the Stone period. A fourth kind (T. dicoccum) differs from all known varieties of this form. A fifth kind (T. monococcum) is known to have existed during the Stone period only by the presence of a single ear. A sixth kind, the common T. spelta, was not introduced into Switzerland until the Bronze age. Of barley, besides the short-eared and small-grained kind, two others were cultivated, one of which was very scarce, and resembled our present common H. distichum. During the Bronze age rye and oats were introduced; the oat-grains being somewhat smaller than those produced by our existing varieties. The poppy was largely cultivated during the Stone period, probably for its oil; but the variety which then existed is not now known. A peculiar pea with small seeds lasted from the Stone to the Bronze age, and then became extinct; whilst a peculiar bean, likewise having small seeds, came in at the Bronze period and lasted to the time of the Romans. These details sound like the descriptions given by palæontologists of the first appearance, the increasing rarity, and final extinction or modification of fossil species, embedded in the successive stages of a geological formation.
Finally, every one must judge for himself whether it is more probable that the several forms of wheat, barley, rye, and oats are descended from between ten and fifteen species, most of which are now either unknown or extinct, or whether they are descended from between four and eight species, which may have either closely resembled our present cultivated forms, or have been so widely different as to escape identification. In this latter case we must conclude that man cultivated the cereals at an enormously remote period, and that he formerly practised some degree of selection, which in itself is not improbable. We may, perhaps, further believe that, when wheat was first cultivated the ears and grains increased quickly in size, in the same manner as the roots of the wild carrot and parsnip are known to increase quickly in bulk under cultivation.
Maize or Indian Corn: Zea mays.—Botanists are nearly unanimous that all the cultivated kinds belong to the same species. It is undoubtedly[[50]] of American origin, and was grown by the aborigines throughout the continent from New England to Chili. Its cultivation must have been extremely ancient, for Tschudi[[51]] describes two kinds, now extinct or not known in Peru, which were taken from tombs apparently prior to the dynasty of the Incas. ‘But there is even stronger evidence of antiquity, for I found on the coast of Peru[[52]] heads of maize, together with eighteen species of recent sea-shell, embedded in a beach which had been upraised at least 85 feet above the level of the sea. In accordance with this ancient cultivation, numerous American varieties have arisen. The aboriginal form has not as yet been discovered in the wild state. A peculiar kind,[[53]] in which the grains, instead of being naked, are concealed by husks as much as eleven lines in length, has been stated, but on insufficient evidence, to grow wild in Brazil. It is almost certain that the aboriginal form would have had its grains thus protected;[[54]] but the seeds of the Brazilian variety produce, as I hear from Professor Asa Gray, and as is stated in two published accounts, either common or husked maize; and it is not credible that a wild species, when first cultivated, should vary so quickly and in so great a degree.
Maize has varied in an extraordinary and conspicuous manner. Metzger,[[55]] who paid particular attention to the cultivation of this plant, makes twelve races (unter-art) with numerous sub-varieties: of the latter some are tolerably constant, others quite inconstant. The different races vary in height from 15-18 feet to only 16-18 inches, as in a dwarf variety described by Bonafous. The whole ear is variable in shape, being long and narrow, or short and thick, or branched. The ear in one variety is more than four times as long as in a dwarf kind. The seeds are arranged in the ear in from six to even twenty rows, or are placed irregularly. The seeds are coloured—white, pale-yellow, orange, red, violet, or elegantly streaked with black;[[56]] and in the same ear there are sometimes seeds of two colours. In a small collection I found that a single grain of one variety nearly equalled in weight seven grains of another variety. The shape of the seed varies greatly, being very flat, or nearly globular, or oval; broader than long, or longer than broad; without any point, or produced into a sharp tooth, and this tooth is sometimes recurved. One variety (the rugosa of Bonafous, and which is extensively cultivated in the United States as sweet corn) has its seeds curiously wrinkled, giving to the whole ear a singular appearance. Another variety (the cymosa of Bon.) carries its ears so crowded together that it is called maïs à bouquet. The seeds of some varieties contain much glucose instead of starch. Male flowers sometimes appear amongst the female flowers, and Mr. J. Scott has lately observed the rarer case of female flowers on a true male panicle, and likewise hermaphrodite flowers.[[57]] Azara describes[[58]] a variety in Paraguay the grains of which are very tender, and he states that several varieties are fitted for being cooked in various ways. The varieties also differ greatly in precocity, and have different powers of resisting dryness and the action of violent wind.[[59]] Some of the foregoing differences would certainly be considered of specific value with plants in a state of nature.
Le Comte Ré states that the grains of all the varieties which he cultivated ultimately assumed a yellow colour. But Bonafous[[60]] found that most of those which he sowed for ten consecutive years kept true to their proper tints; and he adds that in the valleys of the Pyrenees and on the plains of Piedmont a white maize has been cultivated for more than a century, and has undergone no change.
The tall kinds grown in southern latitudes, and therefore exposed to great heat, require from six to seven months to ripen their seed; whereas the dwarf kinds, grown in northern and colder climates, require only from three to four months.[[61]] Peter Kalm,[[62]] who particularly attended to this plant, says, that in the United States, in proceeding from south to north, the plants steadily diminish in bulk. Seeds brought from lat. 37° in Virginia, and sown in lat. 43°-44° in New England, produce plants which will not ripen their seed, or ripen them with the utmost difficulty. So it is with seed carried from New England to lat. 45°-47° in Canada. By taking great care at first, the southern kinds after some years’ culture ripen their seed perfectly in their northern homes, so that this is an analogous case with that of the conversion of summer into winter wheat, and conversely. When tall and dwarf maize are planted together, the dwarf kinds are in full flower before the others have produced a single flower; and in Pennsylvania they ripen their seeds six weeks earlier than the tall maize. Metzger also mentions a European maize which ripens its seed four weeks earlier than another European kind. With these facts, so plainly showing inherited acclimatisation, we may readily believe Kalm, who states that in North America maize and some other plants have gradually been cultivated further and further northward. All writers agree that to keep the varieties of maize pure they must be planted separately so that they shall not cross.
The effects of the climate of Europe on the American varieties is highly remarkable. Metzger obtained seed from various parts of America, and cultivated several kinds in Germany. I will give an abstract of the changes observed[[63]] in one case, namely, with a tall kind (Breit-korniger mais, Zea altissima) brought from the warmer parts of America. During the first year the plants were twelve feet high, and a few seeds were perfected; the lower seeds in the ear kept true to their proper form, but the upper seeds became slightly changed. In the second generation the plants were from nine to ten feet in height, and ripened their seed better; the depression on the outer side of the seed had almost disappeared, and the original beautiful white colour had become duskier. Some of the seeds had even become yellow, and in their now rounded form they approached common European maize. In the third generation nearly all resemblance to the original and very distinct American parent-form was lost. In the sixth generation this maize perfectly resembled a European variety, described as the second sub-variety of the fifth race. When Metzger published his book, this variety was still cultivated near Heidelberg, and could be distinguished from the common kind only by a somewhat more vigorous growth. Analogous results were obtained by the cultivation of another American race, the “white-tooth corn,” in which the tooth nearly disappeared even in the second generation. A third race, the “chicken-corn,” did not undergo so great a change, but the seeds became less polished and pellucid. In the above cases the seeds were carried from a warm to a colder climate. But Fritz Müller informs me that a dwarf variety with small rounded seeds (papa-gaien-mais), introduced from Germany into S. Brazil, produces plants as tall, with seeds as flat, as those of the kind commonly cultivated there.
These facts afford the most remarkable instance known to me of the direct and prompt action of climate on a plant. It might have been expected that the tallness of the stem, the period of vegetation, and the ripening of the seed, would have been thus affected; but it is a much more surprising fact that the seeds should have undergone so rapid and great a change. As, however, flowers, with their product the seed, are formed by the metamorphosis of the stem and leaves, any modification in these latter organs would be apt to extend, through correlation, to the organs of fructification.
Cabbage (Brassica oleracea).—Every one knows how greatly the various kinds of cabbage differ in appearance. In the Island of Jersey, from the effects of particular culture and of climate a stalk has grown to the height of sixteen feet, and “had its spring shoots at the top occupied by a magpie’s nest:” the woody stems are not unfrequently from ten to twelve feet in height, and are there used as rafters[[64]] and as walking-sticks. We are thus reminded that in certain countries plants belonging to the generally herbaceous order of the Cruciferæ are developed into trees. Every one can appreciate the difference between green or red cabbages with great single heads; Brussel-sprouts with numerous little heads; broccolis and cauliflowers with the greater number of their flowers in an aborted condition, incapable of producing seed, and borne in a dense corymb instead of an open panicle; savoys with their blistered and wrinkled leaves; and borecoles and kails, which come nearest to the wild parent-form. There are also various frizzled and laciniated kinds, some of such beautiful colours that Vilmorin in his Catalogue of 1851 enumerates ten varieties which are valued solely for ornament. Some kinds are less commonly known, such as the Portuguese Couve Tronchuda, with the ribs of its leaves greatly thickened; and the Kohlrabi or choux-raves, with their stems enlarged into great turnip-like masses above the ground; and the recently formed new race[[65]] of the choux-raves, already including nine sub-varieties, in which the enlarged part lies beneath the ground like a turnip.
Although we see such great differences in the shape, size, colour, arrangement, and manner of growth of the leaves and stem, and of the flower-stems in the broccoli and cauliflower, it is remarkable that the flowers themselves, the seed-pods and seeds, present extremely slight differences or none at all.[[66]] I compared the flowers of all the principal kinds; those of the Couve Tronchuda are white and rather smaller than in common cabbages; those of the Portsmouth broccoli have narrower sepals, and smaller, less elongated petals; and in no other cabbage could any difference be detected. With respect to the seed-pods, in the purple Kohlrabi alone, do they differ, being a little longer and narrower than usual. I made a collection of the seeds of twenty-eight different kinds, and most of them were undistinguishable; when there was any difference it was excessively slight; thus, the seeds of various broccolis and cauliflowers, when seen in mass, are a little redder; those of the early green Ulm savoy are rather smaller; and those of the Breda kail slightly larger than usual, but not larger than the seeds of the wild cabbage from the coast of Wales. What a contrast in the amount of difference is presented if, on the one hand, we compare the leaves and stems of the various kinds of cabbage with their flowers, pods, and seeds, and on the other hand the corresponding parts in the varieties of maize and wheat! The explanation is obvious; the seeds alone are valued in our cereals, and their variations have been selected; whereas the seeds, seed-pods, and flowers, have been utterly neglected in the cabbage, whilst many useful variations in their leaves and stems have been noticed and preserved from an extremely remote period, for cabbages were cultivated by the old Celts.[[67]]
It would be useless to give a classified description[[68]] of the numerous races, sub-races, and varieties of the cabbage; but it may be mentioned that Dr. Lindley has lately proposed[[69]] a system founded on the state of development of the terminal and lateral leaf-buds. Thus: I. All the leaf-buds active and open, as in the wild-cabbage, kail, etc. II. All the leaf-buds active, but forming heads, as in Brussel-sprouts, etc. III. Terminal leaf-bud alone active, forming a head as in common cabbages, savoys, etc. IV. Terminal leaf-bud alone active, and open, with most of the flowers abortive and succulent, as in the cauliflower and broccoli. V. All the leaf-buds active and open, with most of the flowers abortive and succulent, as in the sprouting-broccoli. This latter variety is a new one, and bears the same relation to common broccoli, as Brussel-sprouts do to common cabbages; it suddenly appeared in a bed of common broccoli, and was found faithfully to transmit its newly-acquired and remarkable characters.
The principal kinds of cabbage existed at least as early as the sixteenth century,[[70]] so that numerous modifications of structure have been inherited for a long period. This fact is the more remarkable as great care must be taken to prevent the crossing of the different kinds. To give proof of this: I raised 233 seedlings from cabbages of different kinds, which had purposely been planted near each other, and of the seedlings no less than 155 were plainly deteriorated and mongrelised; nor were the remaining 78 all perfectly true. It may be doubted whether many permanent varieties have been formed by intentional or accidental crosses; for such crossed plants are found to be very inconstant. One kind, however, called “Cottager’s Kail,” has lately been produced by crossing common kail and Brussel-sprouts, recrossed with purple broccoli,[[71]] and is said to be true; but plants raised by me were not nearly so constant in character as any common kind of cabbage.
Although most of the kinds keep true if carefully preserved from crossing, yet the seed-beds must be yearly examined, and a few seedlings are generally found false; but even in this case the force of inheritance is shown, for, as Metzger has remarked[[72]] when speaking of Brussel-sprouts, the variations generally keep to their “unter art,” or main race. But in order that any kind may be truly propagated there must be no great change in the conditions of life; thus cabbages will not form heads in hot countries, and the same thing has been observed with an English variety grown during an extremely warm and damp autumn near Paris.[[73]] Extremely poor soil also affects the characters of certain varieties.
Most authors believe that all the races are descended from the wild cabbage found on the western shores of Europe; but Alph. De Candolle[[74]] forcibly argues, on historical and other grounds, that it is more probable that two or three closely allied forms, generally ranked as distinct species, still living in the Mediterranean region, are the parents, now all commingled together, of the various cultivated kinds. In the same manner as we have often seen with domesticated animals, the supposed multiple origin of the cabbage throws no light on the characteristic differences between the cultivated forms. If our cabbages are the descendants of three or four distinct species, every trace of any sterility which may originally have existed between them is now lost, for none of the varieties can be kept distinct without scrupulous care to prevent intercrossing.
The other cultivated forms of the genus Brassica are descended, according to the view adopted by Godron and Metzger,[[75]] from two species, B. napus and rapa; but according to other botanists from three species; whilst others again strongly suspect that all these forms, both wild and cultivated, ought to be ranked as a single species. Brassica napus has given rise to two large groups, namely, Swedish turnips (believed to be of hybrid origin)[[76]] and Colzas, the seeds of which yield oil. Brassica rapa (of Koch) has also given rise to two races, namely, common turnips and the oil-giving rape. The evidence is unusually clear that these latter plants, though so different in external appearance, belong to the same species; for the turnip has been observed by Koch and Godron to lose its thick roots in uncultivated soil; and when rape and turnips are sown together they cross to such a degree that scarcely a single plant comes true.[[77]] Metzger by culture converted the biennial or winter rape into the annual or summer rape,—varieties which have been thought by some authors to be specifically distinct.[[78]]
In the production of large, fleshy, turnip-like stems, we have a case of analogous variation in three forms which are generally considered as distinct species. But scarcely any modification seems so easily acquired as a succulent enlargement of the stem or root—that is, a store of nutriment laid up for the plant’s own future use. We see this in our radishes, beet, and in the less generally known “turnip-rooted” celery, and in the finocchio, or Italian variety of the common fennel. Mr. Buckman has lately proved by his interesting experiments bow quickly the roots of the wild parsnip can be enlarged, as Vilmorin formerly proved in the case of the carrot.[[79]]
This latter plant, in its cultivated state, differs in scarcely any character from the wild English carrot, except in general luxuriance and in the size and quality of its roots; but ten varieties, differing in the colour, shape, and quality of the root, are cultivated in England and come true by seed.[[80]] Hence with the carrot, as in so many other cases, for instance with the numerous varieties and sub-varieties of the radish, that part of the plant which is valued by man, falsely appears alone to have varied. The truth is that variations in this part alone have been selected; and the seedlings inheriting a tendency to vary in the same way, analogous modifications have been again and again selected, until at last a great amount of change has been effected.
With respect to the radish, M. Carrière, by sowing the seed of the wild Raphanus raphanistrum in rich soil, and by continued selection during several generations, raised many varieties, closely like the cultivated radish (R. sativus) in their roots, as well as the wonderful Chinese variety, R. caudatus: (see ‘Journal d’Agriculture pratique,’ tom. i, 1869, p. 159; also a separate essay ‘Origine des Plantes Domestiques,’ 1869.) Raphanus raphanistrum and sativus have often been ranked as distinct species, and owing to differences in their fruit even as distinct genera; but Professor Hoffman (‘Bot. Zeitung,’ 1872, p. 482) has now shown that these differences, remarkable as they are, graduate away, the fruit of R. caudatus being intermediate. By cultivating R. raphanistrum during several generations (ibid., 1873, p. 9), Professor Hoffman also obtained plants bearing fruits like those of R. sativus.
Pea (Pisum sativum).—Most botanists look at the garden-pea as specifically distinct from the field-pea (P. arvense). The latter exists in a wild state in Southern Europe; but the aboriginal parent of the garden-pea has been found by one collector alone, as he states, in the Crimea.[[81]] Andrew Knight crossed, as I am informed by the Rev. A. Fitch, the field-pea with a well-known garden variety, the Prussian pea, and the cross seems to have been perfectly fertile. Dr. Alefield has recently studied[[82]] the genus with care, and, after having cultivated about fifty varieties, concludes that certainly they all belong to the same species. It is an interesting fact already alluded to, that, according to O. Heer,[[83]] the peas found in the lake-habitations of Switzerland of the Stone and Bronze ages, belong to an extinct variety, with exceedingly small seeds, allied to P. arvense or the field-pea. The varieties of the common garden-pea are numerous, and differ considerably from one another. For comparison I planted at the same time forty-one, English and French varieties. They differed greatly in height,— namely from between 6 and 12 inches to 8 feet,[[84]]—in manner of growth, and in period of maturity. Some differ in general aspect even while only two or three inches in height. The stems of the Prussian pea are much branched. The tall kinds have larger leaves than the dwarf kinds, but not in strict proportion to their height:—Hair’s Dwarf Monmouth has very large leaves, and the Pois nain hatif, and the moderately tall Blue Prussian, have leaves about two-thirds of the size of the tallest kind. In the Danecroft the leaflets are rather small and a little pointed; in the Queen of Dwarfs rather rounded; and in the Queen of England broad and large. In these three peas the slight differences in the shape of the leaves are accompanied by slight differences in colour, in the Pois géant sans parchemin, which bears purple flowers, the leaflets in the young plant are edged with red; and in all the peas with purple flowers the stipules are marked with red.
In the different varieties, one, two, or several flowers in a small cluster, are borne on the same peduncle; and this is a difference which is considered of specific value in some of the Leguminosæ. In all the varieties the flowers closely resemble each other except in colour and size. They are generally white, sometimes purple, but the colour is inconstant even in the same variety. In Warner’s Emperor, which is a tall kind, the flowers are nearly double the size of the Pois nain hatif; but Hair’s Dwarf Monmouth, which has large leaves, likewise has large flowers. The calyx in the Victoria Marrow is large, and in Bishop’s Long Pod the sepals are rather narrow. In no other kind is there any difference in the flower.
The pods and seeds, which with natural species afford such constant characters, differ greatly in the cultivated varieties of the pea; and these are the valuable, and consequently the selected parts. Sugar peas, or P, are remarkable from their thin pods, which, whilst young, are cooked and eaten whole; and in this group, which, according to Mr. Gordon includes eleven sub-varieties, it is the pod which differs most; thus Lewis’s Negro-podded pea has a straight, broad, smooth, and dark-purple pod, with the husk not so thin as in the other kinds; the pod of another variety is extremely bowed; that of the Pois géant is much pointed at the extremity; and in the variety “à grands cosses” the peas are seen through the husk in so conspicuous a manner that the pod, especially when dry, can hardly at first be recognised as that of a pea.
In the ordinary varieties the pods also differ much in size;—in colour, that of Woodford’s Green Marrow being bright-green when dry, instead of pale brown, and that of the purple-podded pea being expressed by its name;—in smoothness, that of Danecroft being remarkably glossy, whereas that of the Ne plus ultra is rugged; in being either nearly cylindrical, or broad and flat;—in being pointed at the end, as in Thurston’s Reliance, or much truncated, as in the American Dwarf. In the Auvergne pea the whole end of the pod is bowed upwards. In the Queen of the Dwarfs and in Scimitar peas the pod is almost elliptic in shape. I here give drawings of the four most distinct pods produced by the plants cultivated by me.
Fig. 41.—Pods of the Common Pea
In the pea itself we have every tint between almost pure white, brown, yellow, and intense green; in the varieties of the Sugar peas we have these same tints, together with red passing through fine purple into a dark chocolate tint. These colours are either uniform or distributed in dots, striæ, or moss-like marks; they depend in some cases on the colour of the cotyledons seen through the skin, and in other cases on the outer coats of the pea itself. In the different varieties, the pods contain, according to Mr. Gordon, from eleven or twelve to only four or five peas. The largest peas are nearly twice as much in diameter as the smallest; and the latter are not always borne by the most dwarfed kinds. Peas differ much in shape, being smooth and spherical, smooth and oblong, nearly oval in the Queen of the Dwarfs, and nearly cubical and crumpled in many of the larger kinds.
With respect to the value of the differences between the chief varieties, it cannot be doubted that, if one of the tall Sugar-peas, with purple flowers, thin-skinned pods of an extraordinary shape, including large, dark-purple peas, grew wild by the side of the lowly Queen of the Dwarfs, with white flowers, greyish-green, rounded leaves, scimitar-like pods, containing oblong, smooth, pale-coloured peas, which became mature at a different season: or by the side of one of the gigantic sorts, like the Champion of England, with leaves of great size, pointed pods, and large, green, crumpled, almost cubical peas,—all three kinds would be ranked as distinct species.
Andrew Knight[[85]] has observed that the varieties of peas keep very true, because they are not crossed by insects. As far as the fact of keeping true is concerned, I hear from Mr. Masters of Canterbury, well known as the originator of several new kinds, that certain varieties have remained constant for a considerable time,—for instance, Knight’s Blue Dwarf, which came out about the year 1820.[[86]] But the greater number of varieties have a singularly short existence: thus Loudon remarks[[87]] that “sorts which were highly approved in 1821, are now, in 1833, nowhere to be found;” and on comparing the lists of 1833 with those of 1855, I find that nearly all the varieties have changed. Mr. Masters informs me that the nature of the soil causes some varieties to lose their character. As with other plants, certain varieties can be propagated truly, whilst others show a determined tendency to vary; thus two peas differing in shape, one round and the other wrinkled, were found by Mr. Masters within the same pod, but the plants raised from the wrinkled kind always evinced a strong tendency to produce round peas. Mr. Masters also raised from a plant of another variety four distinct sub-varieties, which bore blue and round, white and round, blue and wrinkled, and white and wrinkled peas; and although he sowed these four varieties separately during several successive years, each kind always reproduced all four kinds mixed together!
With respect to the varieties not naturally intercrossing, I have ascertained that the pea, which in this respect differs from some other Leguminosæ, is perfectly fertile without the aid of insects. Yet I have seen humble-bees whilst sucking the nectar depress the keel-petals, and become so thickly dusted with pollen, that it could hardly fail to be left on the stigma of the next flower which was visited. Nevertheless, distinct varieties growing closely together rarely cross; and I have reason to believe that this is due to their stigmas being prematurely fertilised in this country by pollen from the same flower. The horticulturists who raise seed-peas are thus enabled to plant distinct varieties close together without any bad consequences; and it is certain, as I have myself found, that true seed may be saved during at least several generations under these circumstances.[[88]] Mr. Fitch raised, as he informs me, one variety for twenty years, and it always came true, though grown close to other varieties. From the analogy of kidney-beans I should have expected[[89]] that varieties thus circumstanced would have occasionally crossed; and I shall give in the eleventh chapter two cases of this having occurred, as shown (in a manner hereafter to be explained) by the pollen of the one variety having acted directly on the seeds of the other. Whether many of the new varieties which incessantly appear are due to such occasional and accidental crosses, I do not know. Nor do I know whether the short existence of almost all the numerous varieties is the result of mere change of fashion, or of their having a weak constitution, from being the product of long-continued self-fertilisation. It may, however, be noticed that several of Andrew Knight’s varieties, which have endured longer than most kinds, were raised towards the close of the last century by artificial crosses; some of them, I believe, were still vigorous in 1860; but now, in 1865, a writer, speaking[[90]] of Knight’s four kinds of marrows, says, they have acquired a famous history, but their glory has departed.
With respect to Beans (Faba vulgaris), I will say but little. Dr. Alefield has given[[91]] short diagnostic characters of forty varieties. Everyone who has seen a collection must have been struck with the great difference in shape, thickness, proportional length and breadth, colour, and size which beans present. What a contrast between a Windsor and Horse-bean! As in the case of the pea, our existing varieties were preceded during the Bronze age in Switzerland[[92]] by a peculiar and now extinct variety producing very small beans.[[93]]
Potato (Solanum tuberosum).—There is little doubt about the parentage of this plant; for the cultivated varieties differ extremely little in general appearance from the wild species, which can be recognised in its native land at the first glance.[[94]] The varieties cultivated in Britain are numerous; thus Lawson[[95]] gives a description of 175 kinds. I planted eighteen kinds in adjoining rows; their stems and leaves differed but little, and in several cases there was as great a difference between the individuals of the same variety as between the different varieties. The flower varied in size, and in colour between white and purple, but in no other respect, except that in one kind the sepals were somewhat elongated. One strange variety has been described which always produces two sorts of flowers, the first double and sterile, the second single and fertile.[[96]] The fruit or berries also differ, but only in a slight degree.[[97]] The varieties are liable in very different degree to the attack of the Colorado potato-beetle.[[98]]
The tubers, on the other hand, present a wonderful amount of diversity. This fact accords with the principle that the valuable and selected parts of all cultivated productions present the greatest amount of modification. They differ much in size and shape, being globular, oval, flattened, kidney-like, or cylindrical. One variety from Peru is described[[99]] as being quite straight, and at least six inches in length, though no thicker than a man’s finger. The eyes or buds differ in form, position, and colour. The manner in which the tubers are arranged on the so-called roots or rhizomes is different; thus, in the gurken-kartoffeln they form a pyramid with the apex downwards, and in another variety they bury themselves deep in the ground. The roots themselves run either near the surface or deep in the ground. The tubers also differ in smoothness and colour, being externally white, red, purple, or almost black, and internally white, yellow, or almost black. They differ in flavour and quality, being either waxy or mealy; in their period of maturity, and in their capacity for long preservation.
As with many other plants which have been long propagated by bulbs, tubers, cuttings, etc., by which means the same individual is exposed during a length of time to diversified conditions, seedling potatoes generally display innumerable slight differences. Several varieties, even when propagated by tubers, are far from constant, as will be seen in the chapter on Bud-variation. Dr. Anderson[[100]] procured seed from an Irish purple potato, which grew far from any other kind, so that it could not at least in this generation have been crossed, yet the many seedlings varied in almost every possible respect, so that “scarcely two plants were exactly alike.” Some of the plants which closely resembled each other above ground, produced extremely dissimilar tubers; and some tubers which externally could hardly be distinguished, differed widely in quality when cooked. Even in this case of extreme variability, the parent-stock had some influence on the progeny, for the greater number of the seedlings resembled in some degree the parent Irish potato. Kidney potatoes must be ranked amongst the most highly cultivated and artificial races; nevertheless their peculiarities can often be strictly propagated by seed. A great authority, Mr. Rivers,[[101]] states that “seedlings from the ash-leaved kidney always bear a strong resemblance to their parent. Seedlings from the fluke-kidney are still more remarkable for their adherence to their parent stock, for, on closely observing a great number during two seasons, I have not been able to observe the least difference, either in earliness, productiveness, or in the size or shape of their tubers.”
REFERENCES
[1] ‘Géographie botanique raisonnée,’ 1855, pp. 810 to 991.
[2] Review by Mr. Bentham in ‘Hort. Journal,’ vol. ix 1855, p. 133, entitled, ‘Historical Notes on cultivated Plants,’ by Dr. A. Targioni-Tozzetti. See also ‘Edinburgh Review,’ 1866, p. 510.
[3] ‘Hist. Notes,’ as above by Targioni-Tozzetti.
[4] ‘Considérations sur les Céréales,’ 1842, p. 37. ‘Géographie Bot.,’ 1855, p. 930. “Plus on suppose l’agriculture ancienne et remontant à une époque d’ignorance, plus il est probable que les cultivateurs avaient choisi des especes offrant à l’origine meme un avantage incontestable.”
[5] Dr. Hooker has given me this information. See also his ‘Himalayan Journals,’ 1854, vol. ii. p. 49.
[6] ‘Travels in Central Africa,’ Eng. translat. vol. i. pp. 529 and 390; vol. ii. pp. 29, 265, 270. Livingstone’s ‘Travels,’ p. 551.
[7] For instance in both North and South America. Mr. Edgeworth (‘Journal Proc. Linn. Soc.,’ vol. vi. Bot., 1862, p. 181) states that in the deserts of the Punjab poor women sweep up, “by a whisk into straw baskets,” the seeds of four genera of grasses, namely, of Agrostis, Panicum, Cenchrus, and Pennisetum, as well as the seeds of four other genera belonging to distinct families.
[8] Prof. O. Heer, ‘Die Pflanzen der Pfahlbauten, 1866, aus dem Neujahr. Naturforsch. Geselschaft,’ 1866; and Dr. H. Christ in Rutimeyer’s ‘Die Fauna der Pfahlbauten,’ 1861, s. 226.
[9] ‘Travels,’ p. 535. Du Chaillu, ‘Adventures in Equatorial Africa,’ 1861, p. 445.
[10] In Tierra del Fuego the spot where wigwams had formerly stood could be distinguished at a great distance by the bright green tint of the native vegetation.
[11] ‘American Acad. of Arts and Sciences,’ April 10th, 1860, p. 413. Downing, ‘The Fruits of America,’ 1845, p. 261.
[12] ‘Journals of Expeditions in Australia,’ 1841, vol. ii. p. 292.
[13] Darwin’s ‘Journal of Researches,’ 1845, p. 215.
[14] De Candolle has tabulated the facts in the most interesting manner in his ‘Géographie Bot.,’ p. 986.
[15] ‘Flora of Australia,’ Introduction, p. 110.
[16] For Canada, see J. Cartier’s Voyage in 1534; for Florida, see Narvaez and Ferdinand de Soto’s Voyages. As I have consulted these and other old Voyages in more than one general collection of Voyages, I do not give precise references to the pages. See also, for several references Asa Gray, in the ‘American Journal of Science,’ vol. xxiv. Nov. 1857, p. 441. For the traditions of the natives of New Zealand see Crawfurd’s ‘Grammar and Dict. of the Malay Language,’ 1852, p. 260.
[17] See, for example, Mr. Hewett C. Watson’s remarks on our wild plums and cherries and crabs: ‘Cybele Britannica,’ vol. i. pp. 330, 334, etc. Van Mons (in his ‘Arbres Fruitiers,’ 1835, tom. i. p. 444) declares that he has found the types of all our cultivated varieties in wild seedlings, but then he looks on these seedlings as so many aboriginal stocks.
[18] See A. De Candolle, ‘Géograph. Bot.,’ 1855, p. 928 et seq. Godron, ‘De l’Espèce,’ 1859, tom. ii. p. 70; and Metzger, ‘Die Getreidearten,’ etc., 1841.
[19] Mr. Bentham, in his review, entitled ‘Hist. Notes on cultivated Plants,’ by Dr. A. Targioni-Tozzetti, in ‘Journal of Hort. Soc.,’ vol. ix., 1855, p. 133. He informs me that he still retains the same opinion.
[20] ‘Géograph. Bot.,’ p. 928. The whole subject is discussed with admirable fulness and knowledge.
[21] Godron, ‘De l’Espèce,’ tom. ii. p. 72. A few years ago the excellent, though misinterpreted, observations of M. Fabre led many persons to believe that wheat was a modified descendant of Ægilops; but M. Godron (tom. i. p. 165) has shown by careful experiments that the first step in the series, viz. Ægilops triticoides, is a hybrid between wheat and Æ. ovata. The frequency with which these hybrids spontaneously arise, and the gradual manner in which the Æ. triticoides becomes converted into true wheat, alone leave any doubt with respect to M. Godron’s conclusions.
[22] ‘Die Verbreitungsmittel der Pflanzen,’ 1873, p. 129.
[23] Report to British Association for 1857, p. 207.
[24] ‘Considérations sur les Céréales,’ 1842-43, p. 29.
[25] ‘Travels in the Himalayan Provinces,’ etc., 1841, vol. i. p. 224.
[26] Col. J. Le Couteur on the ‘Varieties of Wheat,’ pp. 23, 79.
[27] Loiseleur-Deslongchamps, ‘Consid. sur les Céréales,’ p. 11.
[28] See an excellent review in Hooker’s ‘Journ. of Botany,’ vol. viii. p. 82 note.
[29] ‘De l’Espèce,’ tom. ii. p. 73.
[30] Ibid., tom. ii. p. 75.
[31] For Dalbret and Philippar, see Loiseleur-Deslongchamps ‘Consid. sur les Céréales,’ pp. 45, 70. Le Couteur on Wheat, pp. 6, 14-17.
[32] See his Essay on ‘Pedigree in Wheat,’ 1862; also paper read before the British Association, 1869, and other publications.
[33] ‘Varieties of Wheat,’ Introduction, p. 6. Marshall, in his ‘Rural Economy of Yorkshire,’ vol. ii. p. 9, remarks that “in every field of corn there is as much variety as in a herd of cattle.”
[34] ‘Gardener’s Chron.’ and ‘Agricult. Gazette,’ 1862, p. 963.
[35] ‘Gardener’s Chron.’ Nov. 1868, p. 1199.
[36] ‘Getreidearten,’ 1841, s. 66, 91, 92, 116, 117.
[37] Quoted by Godron, ‘De l’Espèce,’ vol. ii. p. 74. So it is, according to Metzger (‘Getreidearten,’ s. 18), with summer and winter barley.
[38] Loiseleur-Deslongchamps, ‘Céréales,’ part ii. p. 224. Le Couteur, p. 70. Many other accounts could be added.
[39] ‘Travels in North America,’ 1753-1761, Eng. translat., vol. iii p. 165.
[40] ‘Céréales,’ part ii. pp. 179-183.
[41] ‘On the Varieties of Wheat,’ Introduct., p. 7. See Marshall ‘Rural Econ. of Yorkshire,’ vol. ii. p. 9. With respect to similar cases of adaptation in the varieties of oats, see some interesting papers in the ‘Gardener’s Chron. and Agricult. Gazette,’ 1850, pp. 204, 219.
[42] ‘On the Varieties of Wheat,’ p. 59. Mr. Shirreff, and a higher authority cannot be given (‘Gard. Chron. and Agricult. Gazette,’ 1862, p. 963), says, “I have never seen grain which has either been improved or degenerated by cultivation, so as to convey the change to the succeeding crop.”
[43] Alph. De Candolle, ‘Géograph. Bot.,’ p. 930.
[44] ‘Pflanzen der Pfahlbauten,’ 1866.
[45] ‘Les Céréales,’ p. 94.
[46] Quoted by Le Couteur, p. 16.
[47] A. De Candolle, ‘Geograph. Bot.,’ p. 932.
[48] O. Heer ‘Die Pflanzen der Pfahlbauten,’ 1866. The following passage is quoted from Dr. Christ, in ‘Die Fauna der Pfahlbauten, von Dr. Rütimeyer,’ 1861, s. 225.
[49] Heer, as quoted by Carl Vogt, ‘Lectures on Man,’ Eng. translat., p. 355.
[50] See Alph. De Candolle’s long discussion in his ‘Géograph. Bot.,’ p. 942. With respect to New England, see Silliman’s ‘American Journal,’ vol. xliv. p. 99.
[51] ‘Travels in Peru,’ Eng. translat., p. 177.
[52] ‘Geolog. Observ. on S. America,’ 1846, p. 49.
[53] This maize is figured in Bonafous’ magnificent work, ‘Hist. Nat. du Mais,’ 1836, Pl. v. bis, and in the ‘Journal of Hort. Soc.,’ vol. i. 1846, p. 115, where an account is given of the result of sowing the seed. A young Guarany Indian, on seeing this kind of maize, told Auguste St. Hilaire (see De Candolle, ‘Géograph. Bot.,’ p. 951) that it grew wild in the humid forests of his native land. Mr. Teschemacher. in ‘Proc. Boston Soc. Hist.,’ Oct. 19th, 1842, gives an account of sowing the seed.
[54] Moquin-Tandon, ‘Eléments de Tératologie,’ 1841, p. 126.
[55] ‘Die Getreidearten,’ 1841, s. 208. I have modified a few of Metzger’s statements in accordance with those made by Bonafous in his great work ‘Hist. Nat. du Mais,’ 1836.
[56] Godron ‘De l’Espèce,’ tom. ii. p. 80; Al. De Candolle, ibid., p. 951.
[57] ‘Transact. Bot. Soc. of Edinburgh,’ vol. viii. p. 60.
[58] ‘Voyages dans l’Amérique Méridionale,’ tom. i. p. 147.
[59] Bonafous’ ‘Hist. Nat. du Maïs,’ p. 31.
[60] Ibid., p. 31.
[61] Metzger, ‘Getreidearten,’ s. 206.
[62] ‘Description of Maize,’ by P. Kalm, 1752, in ‘Swedish Acts,’ vol. iv. I have consulted an old English MS. translation.
[63] ‘Getreidearten,’ s. 208.
[64] Cabbage Timber, ‘Gardener’s Chron.,’ 1856, p. 744, quoted from Hooker’s ‘Journal of Botany.’ A walking-stick made from a cabbage-stalk is exhibited in the Museum at Kew.
[65] ‘Journal de la Soc. Imp. d’Horticulture,’ 1855, p. 254, quoted from ‘Gartenflora,’ April, 1855.
[66] Godron ‘De l’Espèce,’ tom. ii. p. 52; Metzger, ‘Syst. Beschreibung der Kult. Kohlarten,’ 1833, s. 6.
[67] Regnier, ‘De l’Economie Publique des Celtes,’ 1818, p. 438.
[68] See the elder De Candolle, in ‘Transact. of Hort. Soc.,’ vol. v.; and Metzger ‘Kohlarten,’ etc.
[69] ‘Gardener’s Chronicle,’ 1859, p. 992.
[70] Alph. De Candolle, ‘Géograph. Bot.’ pp. 842 and 989.
[71] ‘Gardener’s Chron.,’ Feb. 1858, p. 128.
[72] ‘Kohlarten,’ s. 22.
[73] Godron, ‘De l’Espèce,’ tom. ii. p. 52; Metzger, ‘Kohlarten,’ s. 22.
[74] ‘Géograph. Bot.,’ p. 840.
[75] Godron, ‘De l’Espèce,’ tom. ii. p. 54; Metzger, ‘Kohlarten,’ s. 10.
[76] ‘Gardener’s Chron. and Agricult. Gazette,’ 1856, p. 729. See, more especially, ibid., 1868, p. 275: the writer asserts that he planted a variety of cabbage (B. oleracea) close to turnips (B. rapa) and raised from the crossed seedlings true Swedish turnips. These latter plants ought, therefore, to be classed with cabbages or turnips, and not under B. napus.
[77] ‘Gardener’s Chron. and Agricult. Gazette,’ 1855, p. 730.
[78] Metzger, ‘Kohlarten,’ s. 51.
[79] These experiments by Vilmorin have been quoted by many writers. An eminent botanist, Prof. Decaisne, has lately expressed doubts on the subject from his own negative results, but these cannot be valued equally with positive results. On the other hand, M. Carrière has lately stated (‘Gard. Chronicle,’ 1865, p. 1154), that he took seed from a wild carrot, growing far from any cultivated land, and even in the first generation the roots of his seedlings differed in being spindle-shaped, longer, softer, and less fibrous than those of the wild plant. From these seedlings he raised several distinct varieties.
[80] Loudon’s ‘Encyclop. of Gardening,’ p. 835.
[81] Alph. De Candolle ‘Géograph. Bot.,’ 960. Mr. Bentham (‘Hort. Journal,’ vol. ix. 1855, p. 141) believes that garden and field peas belong to the same species, and in this respect he differs from Dr. Targioni.
[82] ‘Botanische Zeitung,’ 1860, s. 204.
[83] ‘Die Pflanzen der Pfahlbauten,’ 1866, s. 23.
[84] A variety called the Rounciva attains this height, as is stated by Mr. Gordon in ‘Transact. Hort. Soc.’ (2nd series), vol. i. 1835, p. 374, from which paper I have taken some facts.
[85] ‘Phil. Tract.,’ 1799, p. 196.
[86] ‘Gardener’s Magazine,’ vol. i., 1826, p. 153.
[87] ‘Encyclopædia of Gardening,’ p. 823.
[88] See Dr. Anderson to the same effect in the ‘Bath Soc. Agricultural Papers,’ vol. iv. p. 87.
[89] I have published full details of experiments on this subject in the ‘Gardener’s Chronicle,’ 1857, Oct. 25th.
[90] ‘Gardener’s Chronicle,’ 1865, p. 387.
[91] ‘Bonplandia,’ x., 1862, s. 348.
[92] Heer, ‘Die Pflanzen der Pfahlbauten,’ 1866, s. 22.
[93] Mr. Bentham informs me that in Poitou and the adjoining parts of France, varieties of Phaseolus vulgaris are extremely numerous, and so different that they were described by Savi as distinct species. Mr. Bentham believes that all are descended from an unknown eastern species. Although the varieties differ so greatly in stature and in their seeds, “there is a remarkable sameness in the neglected characters of foliage and flowers, and especially in the bracteoles, an insignificant character in the eyes even of botanists.”
[94] Darwin, ‘Journal of Researches,’ 1845, p. 285. Sabine, in ‘Transact. Hort. Soc.,’ vol. v. p. 249.
[95] ‘Synopsis of the Vegetable Products of Scotland,’ quoted in Wilson’s ‘British Farming,’ p. 317.
[96] Sir G. Mackenzie, in ‘Gardener’s Chronicle,’ 1845, p. 790.
[97] Putsche und Vertuch ‘Versuch einer Monographie der Kartoffeln,’ 1819, s. 9, 15. See also Dr. Anderson ‘Recreations in Agriculture,’ vol. iv. p. 325.
[98] Walsh, ‘The American Entomologist,’ 1869, p. 160. Also S. Tenney, ‘The American Naturalist,’ May 1871, p. 171.
[99] ‘Gardener’s Chronicle,’ 1862, p. 1052.
[100] ‘Bath Society Agricult. Papers,’ vol. v. p. 127. And ‘Recreations in Agriculture,’ vol. v. p. 86.
[101] ‘Gardener’s Chronicle,’ 1863, p. 643.
CHAPTER X.
PLANTS continued—FRUITS—ORNAMENTAL TREES—FLOWERS.
FRUITS. GRAPES: VARY IN ODD AND TRIFLING PARTICULARS—MULBERRY: THE ORANGE GROUP—SINGULAR RESULTS FROM CROSSING— PEACH AND NECTARINE: BUD VARIATION—ANALOGOUS VARIATION—RELATION TO THE ALMOND—APRICOT—PLUMS: VARIATION IN THEIR STONES— CHERRIES: SINGULAR VARIETIES OF—APPLE—PEAR—STRAWBERRY: INTERBLENDING OF THE ORIGINAL FORMS—GOOSEBERRY: STEADY INCREASE IN SIZE OF THE FRUIT—VARIETIES OF—WALNUT—NUT—CUCURBITACEOUS PLANTS: WONDERFUL VARIATION OF.
ORNAMENTAL TREES. THEIR VARIATION IN DEGREE AND KIND—ASH-TREE—SCOTCH-FIR—HAWTHORN.
FLOWERS. MULTIPLE ORIGIN OF MANY KINDS—VARIATION IN CONSTITUTIONAL PECULIARITIES—KIND OF VARIATION—ROSES: SEVERAL SPECIES CULTIVATED—PANSY—DAHLIA—HYACINTH: HISTORY AND VARIATION OF.
The Vine (Vitis vinifera).—The best authorities consider all our grapes as the descendants of one species which now grows wild in western Asia, which grew wild during the Bronze age in Italy,[[1]] and which has recently been found fossil in a tufaceous deposit in the south of France.[[2]] Some authors, however, entertain much doubt about the single parentage of our cultivated varieties, owing to the number of semi-wild forms found in Southern Europe, especially as described by Clemente[[3]] in a forest in Spain; but as the grape sows itself freely in Southern Europe, and as several of the chief kinds transmit their characters by seed,[[4]] whilst others are extremely variable, the existence of many different escaped forms could hardly fail to occur in countries where this plant has been cultivated from the remotest antiquity. That the vine varies much when propagated by seed, we may infer from the largely increased number of varieties since the earlier historical records. New hot-house varieties are produced almost every year; for instance,[[5]] a golden-coloured variety has been recently raised in England from a black grape without the aid of a cross. Van Mons[[6]] reared a multitude of varieties from the seed of one vine, which was completely separated from all others, so that there could not, at least in this generation, have been any crossing, and the seedlings presented “les analogues de toutes les sortes,” and differed in almost every possible character both in the fruits and foliage.
The cultivated varieties are extremely numerous; Count Odart says that he will not deny that there may exist throughout the world 700 or 800, perhaps even 1000 varieties, but not a third of these have any value. In the catalogue of fruit cultivated in the Horticultural Gardens of London, published in 1842, 99 varieties are enumerated. Wherever the grape is grown many varieties occur: Pallas describes 24 in the Crimea, and Burnes mentions 10 in Cabool. The classification of the varieties has much perplexed writers, and Count Odart is reduced to a geographical system; but I will not enter on this subject, nor on the many and great differences between the varieties. I will merely specify a few curious and trifling peculiarities, all taken from Odart’s highly esteemed work[[7]] for the sake of showing the diversified variability of this plant. Simon has classed grapes into two main divisions, those with downy leaves, and those with smooth leaves, but he admits that in one variety, namely the Rebazo, the leaves are either smooth, or downy; and Odart (p. 70) states that some varieties have the nerves alone, and other varieties their young leaves, downy, whilst the old ones are smooth. The Pedro-Ximenes grape (Odart, p. 397) presents a peculiarity by which it can be at once recognised amongst a host of other varieties, namely, that when the fruit is nearly ripe the nerves of the leaves or even the whole surface becomes yellow. The Barbera d’Asti is well marked by several characters (p. 426), amongst others, “by some of the leaves, and it is always the lowest on the branches, suddenly becoming of a dark red colour.” Several authors in classifying grapes have founded their main divisions on the berries being either round or oblong; and Odart admits the value of this character; yet there is one variety, the Maccabeo (p. 71), which often produces small round, and large oblong, berries in the same bunch. Certain grapes called Nebbiolo (p. 429) present a constant character, sufficient for their recognition, namely, “the slight adherence of that part of the pulp which surrounds the seeds to the rest of the berry, when cut through transversely.” A Rhenish variety is mentioned (p. 228) which likes a dry soil; the fruit ripens well, but at the moment of maturity, if much rain falls, the berries are apt to rot; on the other hand, the fruit of a Swiss variety (p. 243) is valued for well sustaining prolonged humidity. This latter variety sprouts late in the spring, yet matures its fruit early; other varieties (page 362) have the fault of being too much excited by the April sun, and in consequence suffer from frost. A Styrian variety (p. 254) has brittle foot-stalks, so that the clusters of fruit are often blown off; this variety is said to be particularly attractive to wasps and bees. Other varieties have tough stalks, which resist the wind. Many other variable characters could be given, but the foregoing facts are sufficient to show in how many small structural and constitutional details the vine varies. During the vine disease in France certain old groups of varieties[[8]] have suffered far more from mildew than others. Thus “the group of Chasselas, so rich in varieties, did not afford a single fortunate exception;” certain other groups suffered much less; the true old Burgundy, for instance, was comparatively free from disease, and the Carminat likewise resisted the attack. The American vines, which belong to a distinct species, entirely escaped the disease in France; and we thus see that those European varieties which best resist the disease must have acquired in a slight degree the same constitutional peculiarities as the American species.
White Mulberry (Morus alba).—I mention this plant because it has varied in certain characters, namely, in the texture and quality of the leaves, fitting them to serve as food for the domesticated silkworm, in a manner not observed with other plants; but this has arisen simply from such variations in the mulberry having been attended to, selected, and rendered more or less constant. M. de Quatrefages[[9]] briefly describes six kinds cultivated in one valley in France: of these the amourouso produces excellent leaves, but is rapidly being abandoned because it produces much fruit mingled with the leaves: the antofino yields deeply cut leaves of the finest quality, but not in great quantity: the claro is much sought for because the leaves can be easily collected: lastly, the roso bears strong hardy leaves, produced in large quantity, but with the one inconvenience, that they are best adapted for the worms after their fourth moult. MM. Jacquemet-Bonnefont, of Lyon, however, remark in their catalogue (1862) that two sub-varieties have been confounded under the name of the roso, one having leaves too thick for the caterpillars, the other being valuable because the leaves can easily be gathered from the branches without the bark being torn.
In India the mulberry has also given rise to many varieties. The Indian form is thought by many botanists to be a distinct species; but as Royle remarks,[[10]] “so many varieties have been produced by cultivation that it is difficult to ascertain whether they all belong to one species;” they are, as he adds, nearly as numerous as those of the silkworm.
The Orange Group.—We here meet with great confusion in the specific distinction and parentage of the several kinds. Gallesio,[[11]] who almost devoted his life-time to the subject, considers that there are four species, namely, sweet and bitter oranges, lemons, and citrons, each of which has given rise to whole groups of varieties, monsters, and supposed hybrids. One high authority[[12]] believes that these four reputed species are all varieties of the wild Citrus medica, but that the shaddock (Citrus decumana), which is not known in a wild state, is a distinct species; though its distinctness is doubted by another writer “of great authority on such matters,” namely, Dr. Buchanan Hamilton. Alph. De Candolle,[[13]] on the other hand—and there cannot be a more capable judge—advances what he considers sufficient evidence of the orange (he doubts whether the bitter and sweet kinds are specifically distinct), the lemon, and citron, having been found wild, and consequently that they are distinct. He mentions two other forms cultivated in Japan and Java, which he ranks undoubted species; he speaks rather more doubtfully about the shaddock, which varies much, and has not been found wild; and finally he considers some forms, such as Adam’s apple and the bergamotte, as probably hybrids.
I have briefly abstracted these opinions for the sake of showing those who have never attended to such subjects, how perplexing they are. It would, therefore, be useless for my purpose to give a sketch of the conspicuous differences between the several forms. Besides the ever-recurrent difficulty of determining whether forms found wild are truly aboriginal or are escaped seedlings, many of the forms, which must be ranked as varieties, transmit their characters almost perfectly by seed. Sweet and bitter oranges differ in no important respect except in the flavour of their fruit, but Gallesio[[14]] is most emphatic that both kinds can be propagated by seed with absolute certainty. Consequently, in accordance with his simple rule, he classes them as distinct species; as he does sweet and bitter almonds, the peach and nectarine, etc. He admits, however, that the soft-shelled pine-tree produces not only soft-shelled but some hard-shelled seedlings, so that a little greater force in the power of inheritance would, according to this rule, raise a soft-shelled pine-tree into the dignity of an aboriginally created species. The positive assertion made by Macfayden[[15]] that the pips of sweet oranges produced in Jamaica, according to the nature of the soil in which they are sown, either sweet or bitter oranges, is probably an error; for M. Alph. De Candolle informs me that since the publication of his great work he has received accounts from Guiana, the Antilles, and Mauritius, that in these countries sweet oranges faithfully transmit their character. Gallesio found that the willow-leafed and the Little China oranges reproduced their proper leaves and fruit; but the seedlings were not quite equal in merit to their parents. The red-fleshed orange, on the other hand, fails to reproduce itself. Gallesio also observed that the seeds of several other singular varieties all reproduced trees having a peculiar physiognomy, partly resembling their parent-forms. I can adduce another case: the myrtle leaved orange is ranked by all authors as a variety, but is very distinct in general aspect: in my father’s greenhouse, during many years, it rarely yielded any fruit, but at last produced one; and a tree thus raised was identical with the parent-form.
Another and more serious difficulty in determining the rank of the several forms is that, according to Gallesio,[[16]] they largely intercross without artificial aid; thus he positively states that seeds taken from lemon-trees (C. lemonum) growing mingled with the citron (C. medica), which is generally considered as a distinct species, produced a graduated series of varieties between these two forms. Again, an Adam’s apple was produced from the seed of a sweet orange, which grew close to lemons and citrons. But such facts hardly aid us in determining whether to rank these forms as species or varieties; for it is now known that undoubted species of Verbascum, Cistus, Primula, Salix, etc., frequently cross in a state of nature. If indeed it were proved that plants of the orange tribe raised from these crosses were even partially sterile, it would be a strong argument in favour of their rank as species. Gallesio asserts that this is the case; but he does not distinguish between sterility from hybridism and from the effects of culture; and he almost destroys the force of this statement by another[[17]] namely, that when he impregnated the flowers of the common orange with the pollen taken from undoubted varieties of the orange, monstrous fruits were produced, which included “little pulp, and had no seeds, or imperfect seeds.”
In this tribe of plants we meet with instances of two highly remarkable facts in vegetable physiology: Gallesio[[18]] impregnated an orange with pollen from a lemon, and the fruit borne on the mother tree had a raised stripe of peel like that of a lemon both in colour and taste, but the pulp was like that of an orange and included only imperfect seeds. The possibility of pollen from one variety or species directly affecting the fruit produced by another variety of species, is a subject which I shall fully discuss in the following chapter.
The second remarkable fact is, that two supposed hybrids[[19]] (for their hybrid nature was not ascertained), between an orange and either a lemon or citron, produced on the same tree leaves, flowers, and fruit of both pure parent-forms, as well as of a mixed or crossed nature. A bud taken from any one of the branches and grafted on another tree produces either one of the pure kinds or a capricious tree reproducing the three kinds. Whether the sweet lemon, which includes within the same fruit segments of differently flavoured pulp,[[20]] is an analogous case, I know not. But to this subject I shall have to recur.
I will conclude by giving from A. Risso[[21]] a short account of a very singular variety of the common orange. It is the “citrus aurantium fructu variabili,” which on the young shoots produces rounded-oval leaves spotted with yellow, borne on petioles with heart-shaped wings; when these leaves fall off, they are succeeded by longer and narrower leaves, with undulated margins, of a pale-green colour embroidered with yellow, borne on footstalks without wings. The fruit whilst young is pear-shaped, yellow, longitudinally striated, and sweet; but as it ripens, it becomes spherical, of a reddish-yellow, and bitter.
Peach and Nectarine (Amygdalus persica).—The best authorities are nearly unanimous that the peach has never been found wild. It was introduced from Persia into Europe a little before the Christian era, and at this period few varieties existed. Alph. De Candolle,[[22]] from the fact of the peach not having spread from Persia at an earlier period, and from its not having pure Sanscrit or Hebrew names, believes that it is not an aboriginal of Western Asia, but came from the terra incognita of China. The supposition, however, that the peach is a modified almond which acquired its present character at a comparatively late period, would, I presume, account for these facts; on the same principle that the nectarine, the offspring of the peach, has few native names, and became known in Europe at a still later period.
Peach and Almond Stones.
Andrew Knight,[[23]] from finding that a seedling-tree, raised from a sweet almond fertilised by the pollen of a peach, yielded fruit quite like that of a peach, suspected that the peach-tree is a modified almond; and in this he has been followed by various authors.[[24]] A first-rate peach, almost globular in shape, formed of soft and sweet pulp, surrounding a hard, much furrowed, and slightly flattened stone, certainly differs greatly from an almond, with its soft, slightly furrowed, much flattened, and elongated stone, protected by a tough, greenish layer of bitter flesh. Mr. Bentham[[25]] has particularly called attention to the stone of the almond being so much more flattened than that of the peach. But in the several varieties of the almond, the stone differs greatly in the degree to which it is compressed, in size, shape, strength, and in the depth of the furrows, as may be seen in fig. 42 (Nos. 4 to 8) of such kinds as I have been able to collect. With peach-stones also (Nos. 1 to 3) the degree of compression and elongation is seen to vary; so that the stone of the Chinese Honey-peach (No. 3) is much more elongated and compressed than that of the (No. 8) Smyrna almond. Mr. Rivers, of Sawbridgeworth, to whom I am indebted for some of the specimens above figured, and who has had such great horticultural experience, has called my attention to several varieties which connect the almond and the peach. In France there is a variety called the Peach-Almond, which Mr. Rivers formerly cultivated, and which is correctly described in a French catalogue as being oval and swollen, with the aspect of a peach, including a hard stone surrounded by a fleshy covering, which is sometimes eatable.[[26]] A remarkable statement by M. Luizet has recently appeared in the ‘Revue Horticole,’[[27]] namely, that a Peach-almond, grafted on a peach, bore, during 1863 and 1864 almonds alone, but in 1865 bore six peaches and no almonds. M. Carriere, in commenting on this fact, cites the case of a double-flowered almond which, after producing during several years almonds, suddenly bore for two years in succession spherical fleshy peach-like fruits, but in 1865 reverted to its former state and produced large almonds.
Again, as I hear from Mr. Rivers, the double-flowering Chinese peaches resemble almonds in their manner of growth and in their flowers; the fruit is much elongated and flattened, with the flesh both bitter and sweet, but not uneatable, and it is said to be of better quality in China. From this stage one small step leads us to such inferior peaches as are occasionally raised from seed. For instance, Mr. Rivers sowed a number of peach-stones imported from the United States, where they are collected for raising stocks, and some of the trees raised by him produced peaches which were very like almonds in appearance, being small and hard, with the pulp not softening till very late in the autumn. Van Mons[[28]] also states that he once raised from a peach-stone a peach having the aspect of a wild tree, with fruit like that of the almond. From inferior peaches, such as these just described, we may pass by small transitions, through clingstones of poor quality, to our best and most melting kinds. From this gradation, from the cases of sudden variation above recorded, and from the fact that the peach has not been found wild, it seems to me by far the most probable view, that the peach is the descendant of the almond, improved and modified in a marvellous manner.
One fact, however, is opposed to this conclusion. A hybrid, raised by Knight from the sweet almond by the pollen of the peach, produced flowers with little or no pollen, yet bore fruit, having been apparently fertilised by a neighbouring nectarine. Another hybrid, from a sweet almond by the pollen of a nectarine, produced during the first three years imperfect blossoms, but afterwards perfect flowers with an abundance of pollen. If this slight degree of sterility cannot be accounted for by the youth of the trees (and this often causes lessened fertility), or by the monstrous state of the flowers, or by the conditions to which the trees were exposed, these two cases would afford a good argument against the peach being the descendant of the almond.
Whether or not the peach has proceeded from the almond, it has certainly given rise to nectarines, or smooth peaches, as they are called by the French. Most of the varieties, both of the peach and nectarine, reproduce themselves truly by seed. Gallesio[[29]] says he has verified this with respect to eight races of the peach. Mr. Rivers[[30]] has given some striking instances from his own experience, and it is notorious that good peaches are constantly raised in North America from seed. Many of the American sub-varieties come true or nearly true to their kind, such as the white-blossom, several of the yellow-fruited freestone peaches, the blood clingstone, the heath, and the lemon clingstone. On the other hand, a clingstone peach has been known to give rise to a freestone.[[31]] In England it has been noticed that seedlings inherit from their parents flowers of the same size and colour. Some characters, however, contrary to what might have been expected, often are not inherited; such as the presence and form of the glands on the leaves.[[32]] With respect to nectarines, both cling and freestones are known in North America to reproduce themselves by seed.[[33]] In England the new white nectarine was a seedling of the old white, and Mr. Rivers[[34]] has recorded several similar cases. From this strong tendency to inheritance, which both peach and nectarine trees exhibit,—from certain slight constitutional differences[[35]] in their nature,—and from the great difference in their fruit both in appearance and flavour, it is not surprising, notwithstanding that the trees differ in no other respects and cannot even be distinguished, as I am informed by Mr. Rivers, whilst young, that they have been ranked by some authors as specifically distinct. Gallesio does not doubt that they are distinct; even Alph. De Candolle does not appear perfectly assured of their specific identity: and an eminent botanist has quite recently[[36]] maintained that the nectarine “probably constitutes a distinct species.”
Hence it may be worth while to give all the evidence on the origin of the nectarine. The facts in themselves are curious, and will hereafter have to be referred to when the important subject of bud-variation is discussed. It is asserted[[37]] that the Boston nectarine was produced from a peach-stone, and this nectarine reproduced itself by seed.[[38]] Mr. Rivers states[[39]] that from stones of three distinct varieties of the peach he raised three varieties of nectarine; and in one of these cases no nectarine grew near the parent peach-tree. In another instance Mr. Rivers raised a nectarine from a peach, and in the succeeding generation another nectarine from this nectarine.[[40]] Other such instances have been communicated to me, but they need not be given. Of the converse case, namely, of nectarine-stones yielding peach-trees (both free and clingstones), we have six undoubted instances recorded by Mr. Rivers; and in two of these instances the parent nectarines had been seedlings from other nectarines.[[41]]
With respect to the more curious case of full-grown peach-trees suddenly producing nectarines by bud-variation (or sports as they are called by gardeners), the evidence is superabundant; there is also good evidence of the same tree producing both peaches and nectarines, or half-and-half fruit; by this term I mean a fruit with the one-half a perfect peach, and the other half a perfect nectarine.
Peter Collinson in 1741 recorded the first case of a peach-tree producing a nectarine,[[42]] and in 1766 he added two other instances. In the same work, the editor, Sir J. E. Smith, describes the more remarkable case of a tree in Norfolk which usually bore both perfect nectarines and perfect peaches; but during two seasons some of the fruit were half and half in nature.
Mr. Salisbury in 1808[[43]] records six other cases of peach-trees producing nectarines. Three of the varieties are named; viz., the Alberge, Belle Chevreuse, and Royal George. This latter tree seldom failed to produce both kinds of fruit. He gives another case of a half-and-half fruit.
At Radford in Devonshire[[44]] a clingstone peach, purchased as the Chancellor, was planted in 1815, and in 1824, after having previously produced peaches alone, bore on one branch twelve nectarines; in 1825 the same branch yielded twenty-six nectarines, and in 1826 thirty-six nectarines, together with eighteen peaches. One of the peaches was almost as smooth on one side as a nectarine. The nectarines were as dark as, but smaller than, the Elruge.
At Beccles a Royal George peach[[45]] produced a fruit, “three parts of it being peach and one part nectarine, quite distinct in appearance as well as in flavour.” The lines of division were longitudinal, as represented in the woodcut. A nectarine-tree grew five yards from this tree.
Professor Chapman states[[46]] that he has often seen in Virginia very old peach-trees bearing nectarines.
A writer in the ‘Gardener’s Chronicle’ says that a peach tree planted fifteen years previously[[47]] produced this year a nectarine between two peaches; a nectarine-tree grew close by.
In 1844[[48]] a Vanguard peach-tree produced, in the midst of its ordinary fruit, a single red Roman nectarine.
Mr. Calver is stated[[49]] to have raised in the United States a seedling peach which produced a mixed crop of both peaches and nectarines.
Near Dorking[[50]] a branch of the Téton de Vénus peach, which reproduces itself truly by seed,[[51]] bore its own fruit “so remarkable for its prominent point, and a nectarine rather smaller but well formed and quite round.”
The previous cases all refer to peaches suddenly producing nectarines, but at Carclew[[52]] the unique case occurred, of a nectarine-tree, raised twenty years before from seed and never grafted, producing a fruit half peach and half nectarine; subsequently bore a perfect peach.
To sum up the foregoing facts; we have excellent evidence of peach-stones producing nectarine-trees, and of nectarine-stones producing peach-Trees,—of the same tree bearing peaches and nectarines,—of peach-trees suddenly producing by bud-variation nectarines (such nectarines reproducing nectarines by seed), as well as fruit in part nectarine and in part peach,—and, lastly, of one nectarine-tree first bearing half-and-half fruit, and subsequently true peaches. As the peach came into existence before the nectarine, it might have been expected from the law of reversion that nectarines would have given birth by bud-variation or by seed to peaches, oftener than peaches to nectarines; but this is by no means the case.
Two explanations have been suggested to account for these conversions. First, that the parent trees have been in every case hybrids[[53]] between the peach and nectarine, and have reverted by bud-variation or by seed to one of their pure parent forms. This view in itself is not very improbable; for the Mountaineer peach, which was raised by Knight from the red nutmeg-peach by pollen of the violette hâtive nectarine,[[54]] produces peaches, but these are said sometimes to partake of the smoothness and flavour of the nectarine. But let it be observed that in the previous list no less than six well-known varieties and several unnamed varieties of the peach have once suddenly produced perfect nectarines by bud variation: and it would be an extremely rash supposition that all these varieties of the peach, which have been cultivated for years in many districts, and which show not a vestige of a mixed parentage, are, nevertheless, hybrids. A second explanation is, that the fruit of the peach has been directly affected by the pollen of the nectarine: although this certainly is possible, it cannot here apply; for we have not a shadow of evidence that a branch which has borne fruit directly affected by foreign pollen is so profoundly modified as afterwards to produce buds which continue to yield fruit of the new and modified form. Now it is known that when a bud on a peach-tree has once borne a nectarine the same branch has in several instances gone on during successive years producing nectarines. The Carclew nectarine, on the other hand, first produced half-and-half fruit, and subsequently pure peaches. Hence we may confidently accept the common view that the nectarine is a variety of the peach, which may be produced either by bud-variation or from seed. In the following chapter many analogous cases of bud-variation will he given.
The varieties of the peach and the nectarine run in parallel lines. In both classes the kinds differ from each other in the flesh of the fruit being white, red, or yellow; in being clingstones or freestones; in the flowers being large or small, with certain other characteristic differences; and in the leaves being serrated without glands, or crenated and furnished with globose or reniform glands.[[55]] We can hardly account for this parallelism by supposing that each variety of the nectarine is descended from a corresponding variety of the peach; for though our nectarines are certainly the descendants of several kinds of peaches, yet a large number are the descendants of other nectarines, and they vary so much when thus reproduced that we can scarcely admit the above explanation.
The varieties of the peach have largely increased in number since the Christian era, when from two to five varieties were known;[[56]] and the nectarine was unknown. At the present time, besides many varieties said to exist in China, Downing describes, in the United States, seventy-nine native and imported varieties of the peach; and a few years ago Lindley[[57]] enumerated one hundred and sixty-four varieties of the peach and nectarine grown in England. I have already indicated the chief points of difference between the several varieties. Nectarines, even when produced from distinct kinds of peaches, always possess their own peculiar flavour, and are smooth and small. Clingstone and freestone peaches, which differ in the ripe flesh either firmly adhering to the stone, or easily separating from it, also differ in the character of the stone itself; that of the freestones or melters being more deeply fissured, with the sides of the fissures smoother than in clingstones. In the various kinds the flowers differ not only in size, but in the larger flowers the petals are differently shaped, more imbricated, generally red in the centre and pale towards the margin: whereas in the smaller flowers the margin of the petal is usually more darkly coloured. One variety has nearly white flowers. The leaves are more or less serrated, and are either destitute of glands, or have globose or reniform glands;[[58]] and some few peaches, such as the Brugnen, bear on the same tree both globular and kidney-shaped glands.[[59]] According to Robertson[[60]] the trees with glandular leaves are liable to blister, but not in any great degree to mildew; whilst the non-glandular trees are more subject to curl, to mildew, and to the attacks of aphides. The varieties differ in the period of their maturity, in the fruit keeping well, and in hardiness,—the latter circumstance being especially attended to in the United States. Certain varieties, such as the Bellegarde, stand forcing in hot-houses better than other varieties. The flat-peach of China is the most remarkable of all the varieties; it is so much depressed towards the summit, that the stone is here covered only by roughened skin and not by a fleshy layer.[[61]] Another Chinese variety, called the Honey-peach, is remarkable from the fruit terminating in a long sharp point; its leaves are glandless and widely dentate.[[62]] The Emperor of Russia peach is a third singular variety, having deeply double-serrated leaves; the fruit is deeply cleft with one-half projecting considerably beyond the other: it originated in America, and its seedlings inherit similar leaves.[[63]]
The peach has also produced in China a small class of trees valued for ornament, namely the double-flowered; of these, five varieties are now known in England, varying from pure white, through rose, to intense crimson.[[64]] One of these varieties, called the camellia-flowered, bears flowers above 2¼ inches in diameter, whilst those of the fruit-bearing kinds do not at most exceed 1¼ inch in diameter. The flowers of the double-flowered peaches have the singular property[[65]] of frequently producing double or treble fruit. Finally, there is good reason to believe that the peach is an almond profoundly modified; but whatever its origin may have been, there can be no doubt that it has yielded during the last eighteen centuries many varieties, some of them strongly characterised, belonging both to the nectarine and peach form.
Apricot (Prunus armeniaca).—It is commonly admitted that this tree is descended from a single species, now found wild in the Caucasian region.[[66]] On this view the varieties deserve notice, because they illustrate differences supposed by some botanists to be of specific value in the almond and plum. The best monograph on the apricot is by Mr. Thompson,[[67]] who describes seventeen varieties. We have seen that peaches and nectarines vary in a strictly parallel manner; and in the apricot, which forms a closely allied genus, we again meet with variations analogous to those of the peach, as well as to those of the plum. The varieties differ considerably in the shape of their leaves, which are either serrated or crenated, sometimes with ear-like appendages at their bases, and sometimes with glands on the petioles. The flowers are generally alike, but are small in the Masculine. The fruit varies much in size, shape, and in having the suture little pronounced or absent; in the skin being smooth, or downy, as in the orange-apricot; and in the flesh clinging to the stone, as in the last-mentioned kind, or in readily separating from it, as in the Turkey-apricot. In all these differences we see the closest analogy with the varieties of the peach and nectarine. In the stone we have more important differences, and these in the case of the plum have been esteemed of specific value: in some apricots the stone is almost spherical, in others much flattened, being either sharp in front or blunt at both ends, sometimes channelled along the back, or with a sharp ridge along both margins. In the Moorpark, and generally in the Hemskirke, the stone presents a singular character in being perforated, with a bundle of fibres passing through the perforation from end to end. The most constant and important character, according to Thompson, is whether the kernel is bitter or sweet: yet in this respect we have a graduated difference, for the kernel is very bitter in Shipley’s apricot; in the Hemskirke less bitter than in some other kinds; slightly bitter in the Royal; and “sweet like a hazel-nut” in the Breda, Angoumois, and others. In the case of the almond, bitterness has been thought by some high authorities to indicate specific difference.
In N. America the Roman apricot endures “cold and unfavourable situations, where no other sort, except the Masculine, will succeed; and its blossoms bear quite a severe frost without injury.”[[68]] According to Mr. Rivers,[[69]] seedling apricots deviate but little from the character of their race: in France the Alberge is constantly reproduced from seed with but little variation. In Ladakh, according to Moorcroft,[[70]] ten varieties of the apricot, very different from each other, are cultivated, and all are raised from seed, excepting one, which is budded.
Plum Stones.
Plums (Prunus insititia).—Formerly the sloe, P. spinosa, was thought to be the parent of all our plums; but now this honour is very commonly accorded to P. insititia or the bullace, which is found wild in the Caucasus and N.-Western India, and is naturalised in England.[[71]] It is not at all improbable, in accordance with some observations made by Mr. Rivers,[[72]] that both these forms, which some botanists rank as a single species, may be the parents of our domesticated plums. Another supposed parent-form, the P. domestica, is said to be found wild in the region of the Caucasus. Godron remarks[[73]] that the cultivated varieties may be divided into two main groups, which he supposes to be descended from two aboriginal stocks; namely, those with oblong fruit and stones pointed at both ends, having narrow separate petals and upright branches; and those with rounded fruit, with stones blunt at both ends, with rounded petals and spreading branches. From what we know of the variability of the flowers in the peach and of the diversified manner of growth in our various fruit-trees, it is difficult to lay much weight on these latter characters. With respect to the shape of the fruit, we have conclusive evidence that it is extremely variable: Downing[[74]] gives outlines of the plums of two seedlings, namely, the red and imperial gages, raised from the greengage; and the fruit of both is more elongated than that of the greengage. The latter has a very blunt broad stone, whereas the stone of the imperial gage is “oval and pointed at both ends.” These trees also differ in their manner of growth: “the greengage is a very short-jointed, slow-growing tree, of spreading and rather dwarfish habit;” whilst its offspring, the imperial gage, “grows freely and rises rapidly, and has long dark shoots.” The famous Washington plum bears a globular fruit, but its offspring, the emerald drop, is nearly as much elongated as the most elongated plum figured by Downing, namely, Manning’s prune. I have made a small collection of the stones of twenty-five kinds, and they graduate in shape from the bluntest into the sharpest kinds. As characters derived from seeds are generally of high systematic importance, I have thought it worth while to give drawings of the most distinct kinds in my small collection; and they may be seen to differ in a surprising manner in size, outline, thickness, prominence of the ridges, and state of surface. It deserves notice that the shape of the stone is not always strictly correlated with that of the fruit: thus the Washington plum is spherical and depressed at the pole, with a somewhat elongated stone, whilst the fruit of the Goliath is more elongated, but the stone less so, than in the Washington. Again, Denyer’s Victoria and Goliath bear fruit closely resembling each other, but their stones are widely different. On the other hand, the Harvest and Black Margate plums are very dissimilar, yet include closely similar stones.
The varieties of the plum are numerous, and differ greatly in size, shape, quality, and colour,—being bright yellow, green, almost white, blue, purple, or red. There are some curious varieties, such as the double or Siamese, and the Stoneless plum: in the latter the kernel lies in a roomy cavity surrounded only by the pulp. The climate of North America appears to be singularly favourable for the production of new and good varieties; Downing describes no less than forty, of which seven of first-rate quality have been recently introduced into England.[[75]] Varieties occasionally arise having an innate adaptation for certain soils, almost as strongly pronounced as with natural species growing on the most distinct geological formations; thus in America the imperial gage, differently from almost all other kinds, “is peculiarly fitted for dry light soils where many sorts drop their fruit,” whereas on rich heavy soils the fruit is often insipid.[[76]] My father could never succeed in making the Wine-Sour yield even a moderate crop in a sandy orchard near Shrewsbury, whilst in some parts of the same county and in its native Yorkshire it bears abundantly: one of my relations also repeatedly tried in vain to grow this variety in a sandy district in Staffordshire.
Mr. Rivers has given[[77]] a number of interesting facts, showing how truly many varieties can be propagated by seed. He sowed the stones of twenty bushels of the greengage for the sake of raising stocks, and closely observed the seedlings; all had the smooth shoots, the prominent buds, and the glossy leaves of the greengage, but the greater number had smaller leaves and thorns. There are two kinds of damson, one the Shropshire with downy shoots, and the other the Kentish with smooth shoots, and these differ but slightly in any other respect: Mr. Rivers sowed some bushels of the Kentish damson, and all the seedlings had smooth shoots, but in some the fruit was oval, in others round or roundish, and in a few the fruit was small, and, except in being sweet, closely resembled that of the wild sloe. Mr. Rivers gives several other striking instances of inheritance: thus, he raised eighty thousand seedlings from the common German Quetsche plum, and “not one could be found varying in the least, in foliage or habit.” Similar facts were observed with the Petite Mirabelle plum, yet this latter kind (as well as the Quetsche) is known to have yielded some well-established varieties; but, as Mr. Rivers remarks, they all belong to the same group with the Mirabelle.
Cherries (Prunus cerasus, avium, etc.).—Botanists believe that our cultivated cherries are descended from one, two, four, or even more wild stocks.[[78]] That there must be at least two parent species we may infer from the sterility of twenty hybrids raised by Mr. Knight from the morello fertilised by pollen of the Elton cherry; for these hybrids produced in all only five cherries, and one alone of these contained a seed.[[79]] Mr. Thompson[[80]] has classified the varieties in an apparently natural method in two main groups by characters taken from the flowers, fruit, and leaves; but some varieties which stand widely separate in this classification are quite fertile when crossed; thus Knight’s Early Black cherries are the product of a cross between two such kinds.
Mr. Knight states that seedling cherries are more variable than those of any other fruit-tree.[[81]] In the Catalogue of the Horticultural Society for 1842 eighty varieties are enumerated. Some varieties present singular characters: thus, the flower of the Cluster cherry includes as many as twelve pistils, of which the majority abort; and they are said generally to produce from two to five or six cherries aggregated together and borne on a single peduncle. In the Ratafia cherry several flower-peduncles arise from a common peduncle, upwards of an inch in length. The fruit of Gascoigne’s Heart has its apex produced into a globule or drop; that of the white Hungarian Gean has almost transparent flesh. The Flemish cherry is “a very odd-looking fruit,” much flattened at the summit and base, with the latter deeply furrowed, and borne on a stout, very short footstalk. In the Kentish cherry the stone adheres so firmly to the footstalk, that it could be drawn out of the flesh; and this renders the fruit well fitted for drying. The Tobacco-leaved cherry, according to Sageret and Thompson, produces gigantic leaves, more than a foot and sometimes even eighteen inches in length, and half a foot in breadth. The weeping cherry, on the other hand, is valuable only as an ornament, and, according to Downing, is “a charming little tree, with slender, weeping branches, clothed with small, almost myrtle-like foliage.” There is also a peach-leaved variety.
Sageret describes a remarkable variety, le griottier de la Toussaint, which bears at the same time, even as late as September, flowers and fruit of all degrees of maturity. The fruit, which is of inferior quality, is borne on long, very thin footstalks. But the extraordinary statement is made that all the leaf-bearing shoots spring from old flower-buds. Lastly, there is an important physiological distinction between those kinds of cherries which bear fruit on young or on old wood; but Sageret positively asserts that a Bigarreau in his garden bore fruit on wood of both ages.[[82]]
Apple (Pyrus malus).—The one source of doubt felt by botanists with respect to the parentage of the apple is whether, besides P. malus, two or three other closely allied wild forms, namely, P. acerba and præcox or paradisiaca, do not deserve to be ranked as distinct species. The P. præcox is supposed by some authors[[83]] to be the parent of the dwarf paradise stock, which, owing to the fibrous roots not penetrating deeply into the ground, is so largely used for grafting; but the paradise stocks, it is asserted,[[84]] cannot be propagated true by seed. The common wild crab varies considerably in England; but many of the varieties are believed to be escaped seedlings.[[85]] Every one knows the great difference in the manner of growth, in the foliage, flowers, and especially in the fruit, between the almost innumerable varieties of the apple. The pips or seeds (as I know by comparison) likewise differ considerably in shape, size, and colour. The fruit is adapted for eating or for cooking in various ways, and keeps for only a few weeks or for nearly two years. Some few kinds have the fruit covered with a powdery secretion, called bloom, like that on plums; and “it is extremely remarkable that this occurs almost exclusively among varieties cultivated in Russia.”[[86]] Another Russian apple, the white Astracan, possesses the singular property of becoming transparent, when ripe, like some sorts of crabs. The api étoilé has five prominent ridges, hence its name; the api noir is nearly black: the twin cluster pippin often bears fruit joined in pairs.[[87]] The trees of the several sorts differ greatly in their periods of leafing and flowering; in my orchard the Court Pendu Plat produces leaves so late, that during several springs I thought that it was dead. The Tiffin apple scarcely bears a leaf when in full bloom; the Cornish crab, on the other hand, bears so many leaves at this period that the flowers can hardly be seen.[[88]] In some kinds the fruit ripens in mid-summer; in others, late in the autumn. These several differences in leafing, flowering, and fruiting, are not at all necessarily correlated; for, as Andrew Knight has remarked,[[89]] no one can judge from the early flowering of a new seedling, or from the early shedding or change of colour of the leaves, whether it will mature its fruit early in the season.
The varieties differ greatly in constitution. It is notorious that our summers are not hot enough for the Newtown Pippin,[[90]] which is the glory of the orchards near New York; and so it is with several varieties which we have imported from the Continent. On the other hand, our Court of Wick succeeds well under the severe climate of Canada. The Caville rouge de Micoud occasionally bears two crops during the same year. The Burr Knot is covered with small excrescences, which emit roots so readily that a branch with blossom-buds may be stuck in the ground, and will root and bear a few fruit even during the first year.[[91]] Mr. Rivers has recently described[[92]] some seedlings valuable from their roots running near the surface. One of these seedlings was remarkable from its extremely dwarfed size, “forming itself into a bush only a few inches in height.” Many varieties are particularly liable to canker in certain soils. But perhaps the strangest constitutional peculiarity is that the Winter Majetin is not attacked by the mealy bug or coccus; Lindley[[93]] states that in an orchard in Norfolk infested with these insects the Majetin was quite free, though the stock on which it was grafted was affected: Knight makes a similar statement with respect to a cider apple, and adds that he only once saw these insects just above the stock, but that three days afterwards they entirely disappeared; this apple, however, was raised from a cross between the Golden Harvey and the Siberian Crab; and the latter, I believe, is considered by some authors as specifically distinct.
The famous St. Valery apple must not be passed over; the flower has a double calyx with ten divisions, and fourteen styles surmounted by conspicuous oblique stigmas, but is destitute of stamens or corolla. The fruit is constricted round the middle, and is formed of five seed-cells, surmounted by nine other cells.[[94]] Not being provided with stamens, the tree requires artificial fertilisation; and the girls of St. Valery annually go to “faire ses pommes,” each marking her own fruit with a ribbon; and as different pollen is used the fruit differs, and we here have an instance of the direct action of foreign pollen on the mother plant. These monstrous apples include, as we have seen, fourteen seed-cells; the pigeon-apple,[[95]] on the other hand, has only four, instead of, as with all common apples, five cells; and this certainly is a remarkable difference.
In the catalogue of apples published in 1842 by the Horticultural Society, 897 varieties are enumerated; but the differences between most of them are of comparatively little interest, as they are not strictly inherited. No one can raise, for instance, from the seed of the Ribston Pippin, a tree of the same kind; and it is said that the “Sister Ribston Pippin” was a white semi-transparent, sour-fleshed apple, or rather large crab.[[96]] Yet it was a mistake to suppose that with most varieties the characters are not to a certain extent inherited. In two lots of seedlings raised from two well-marked kinds, many worthless crab-like seedlings will appear, but it is now known that the two lots not only usually differ from each other, but resemble to a certain extent their parents. We see this indeed in the several sub-groups of Russetts, Sweetings, Codlins, Pearmains, Reinettes, etc.,[[97]] which are all believed, and many are known, to be descended from other varieties bearing the same names.
Pears (Pyrus communis).—I need say little on this fruit, which varies much in the wild state, and to an extraordinary degree when cultivated, in its fruit, flowers, and foliage. One of the most celebrated botanists in Europe, M. Decaisne, has carefully studied the many varieties;[[98]] although he formerly believed that they were derived from more than one species, he now thinks that all belong to one. He has arrived at this conclusion from finding in the several varieties a perfect gradation between the most extreme characters; so perfect is this gradation that he maintains it to be impossible to classify the varieties by any natural method. M. Decaisne raised many seedlings from four distinct kinds, and has carefully recorded the variations in each. Notwithstanding this extreme degree of variability, it is now positively known that many kinds reproduce by seed the leading characters of their race.[[99]]
Strawberries (Fragaria).—This fruit is remarkable on account of the number of species which have been cultivated, and from their rapid improvement within the last fifty or sixty years. Let any one compare the fruit of one of the largest varieties exhibited at our Shows with that of the wild wood strawberry, or, which will be a fairer comparison, with the somewhat larger fruit of the wild American Virginian Strawberry, and he will see what prodigies horticulture has effected.[[100]] The number of varieties has likewise increased in a surprisingly rapid manner. Only three kinds were known in France, in 1746, where this fruit was early cultivated. In 1766 five species had been introduced, the same which are now cultivated, but only five varieties of Fragaria vesca, with some sub-varieties, had been produced. At the present day the varieties of the several species are almost innumerable. The species consist of, firstly, the wood or Alpine cultivated strawberries, descended from F. vesca, a native of Europe and of North America. There are eight wild European varieties, as ranked by Duchesne, of F. vesca, but several of these are considered species by some botanists. Secondly, the green strawberries, descended from the European F. collina, and little cultivated in England. Thirdly, the Hautbois, from the European F. elatior. Fourthly, the Scarlets, descended from F. virginiana, a native of the whole breadth of North America. Fifthly, the Chili, descended from F. chiloensis, an inhabitant of the west coast of the temperate parts both of North and South America. Lastly, the pines or Carolinas (including the old Blacks), which have been ranked by most authors under the name of F. grandiflora as a distinct species, said to inhabit Surinam; but this is a manifest error. This form is considered by the highest authority, M. Gay, to be merely a strongly marked race of F. chiloensis.[[101]] These five or six forms have been ranked by most botanists as specifically distinct; but this may be doubted, for Andrew Knight,[[102]] who raised no less than 400 crossed strawberries, asserts that the F. virginiana, chiloensis and grandiflora “may be made to breed together indiscriminately,” and he found, in accordance with the principle of analogous variation, “that similar varieties could be obtained from the seeds of any one of them.”
Since Knight’s time there is abundant and additional evidence[[103]] of the extent to which the American forms spontaneously cross. We owe indeed to such crosses most of our choicest existing varieties. Knight did not succeed in crossing the European wood-strawberry with the American Scarlet or with the Hautbois. Mr. Williams of Pitmaston, however, succeeded; but the hybrid offspring from the Hautbois, though fruiting well, never produced seed, with the exception of a single one, which reproduced the parent hybrid form.[[104]] Major R. Trevor Clarke informs me that he crossed two members of the Pine class (Myatt’s B. Queen and Keen’s Seedling) with the wood and hautbois, and that in each case he raised only a single seedling; one of these fruited, but was almost barren. Mr. W. Smith, of York, has raised similar hybrids with equally poor success.[[105]] We thus see[[106]] that the European and American species can with some difficulty be crossed; but it is improbable that hybrids sufficiently fertile to be worth cultivation will ever be thus produced. This fact is surprising, as these forms structurally are not widely distinct, and are sometimes connected in the districts where they grow wild, as I hear from Professor Asa Gray, by puzzling intermediate forms.
The energetic culture of the Strawberry is of recent date, and the cultivated varieties can in most cases be classed under some one of the above native stocks. As the American strawberries cross so freely and spontaneously, we can hardly doubt that they will ultimately become inextricably confused. We find, indeed, that horticulturists at present disagree under which class to rank some few of the varieties; and a writer in the ‘Bon Jardinier’ of 1840 remarks that formerly it was possible to class all of them under some one species, but that now this is quite impossible with the American forms, the new English varieties having completely filled up the gaps between them.[[107]] The blending together of two or more aboriginal forms, which there is every reason to believe has occurred with some of our anciently cultivated productions, we see now actually occurring with our strawberries.
The cultivated species offer some variations worth notice. The Black Prince, a seedling from Keen’s Imperial (this latter being a seedling of a very white strawberry, the white Carolina), is remarkable from “its peculiar dark and polished surface, and from presenting an appearance entirely unlike that of any other kind.”[[108]] Although the fruit in the different varieties differs so greatly in form, size, colour, and quality, the so-called seed (which corresponds with the whole fruit in the plum) with the exception of being more or less deeply embedded in the pulp, is, according to De Jonghe,[[109]] absolutely the same in all: and this no doubt may be accounted for by the seed being of no value, and consequently not having been subjected to selection. The strawberry is properly three-leaved, but in 1761 Duchesne raised a single-leaved variety of the European wood-strawberry, which Linnæus doubtfully raised to the rank of a species. Seedlings of this variety, like those of most varieties not fixed by long-continued selection, often revert to the ordinary form, or present intermediate states.[[110]] A variety raised by Mr. Myatt,[[111]] apparently belonging to one of the American forms presents a variation of an opposite nature, for it has five leaves; Godron and Lambertye also mention a five-leaved variety of F. collina.
The Red Bush Alpine strawberry (one of the F. vesca section) does not produce stolons or runners, and this remarkable deviation of structure is reproduced truly by seed. Another sub-variety, the White Bush Alpine, is similarly characterised, but when propagated by seed it often degenerates and produces plants with runners.[[112]] A strawberry of the American Pine section is also said to make but few runners.[[113]]
Much has been written on the sexes of strawberries; the true Hautbois properly bears the male and female organs on separate plants,[[114]] and was consequently named by Duchesne dioica; but it frequently produces hermaphrodites; and Lindley,[[115]] by propagating such plants by runners, at the same time destroying the males, soon raised a self-prolific stock. The other species often showed a tendency towards an imperfect separation of the sexes, as I have noticed with plants forced in a hot-house. Several English varieties, which in this country are free from any such tendency, when cultivated in rich soils under the climate of North America[[116]] commonly produce plants with separate sexes. Thus a whole acre of Keen’s Seedlings in the United States has been observed to be almost sterile from the absence of male flowers; but the more general rule is, that the male plants overrun the females. Some members of the Cincinnati Horticultural Society, especially appointed to investigate this subject, report that “few varieties have the flowers perfect in both sexual organs,” etc. The most successful cultivators in Ohio plant for every seven rows of “pistillata,” or female plants, one row of hermaphrodites, which afford pollen for both kinds; but the hermaphrodites, owing to their expenditure in the production of pollen, bear less fruit than the female plants.
The varieties differ in constitution. Some of our best English kinds, such as Keen’s Seedlings, are too tender for certain parts of North America, where other English and many American varieties succeed perfectly. That splendid fruit, the British Queen, can be cultivated but in few places either in England or France: but this apparently depends more on the nature of the soil than on the climate; a famous gardener says that “no mortal could grow the British Queen at Shrubland Park unless the whole nature of the soil was altered.”[[117]] La Constantine is one of the hardiest kinds, and can withstand Russian winters, but it is easily burnt by the sun, so that it will not succeed in certain soils either in England or the United States.[[118]] The Filbert Pine Strawberry “requires more water than any other variety; and if the plants once suffer from drought, they will do little or no good afterwards.”[[119]] Cuthill’s Black Prince Strawberry evinces a singular tendency to mildew; no less than six cases have been recorded of this variety suffering severely, whilst other varieties growing close by, and treated in exactly the same manner, were not at all infested by this fungus.[[120]] The time of maturity differs much in the different varieties: some belonging to the wood or alpine section produce a succession of crops throughout the summer.
Gooseberry (Ribes grossularia).—No one, I believe, has hitherto doubted that all the cultivated kinds are sprung from the wild plant bearing this name, which is common in Central and Northern Europe; therefore it will be desirable briefly to specify all the points, though not very important, which have varied. If it be admitted that these differences are due to culture, authors perhaps will not be so ready to assume the existence of a large number of unknown wild parent-stocks for our other cultivated plants. The gooseberry is not alluded to by writers of the classical period. Turner mentions it in 1573, and Parkinson specifies eight varieties in 1629; the Catalogue of the Horticultural Society for 1842 gives 149 varieties, and the lists of the Lancashire nurserymen are said to include above 300 names.[[121]] In the ‘Gooseberry Grower’s Register’ for 1862 I find that 243 distinct varieties have won prizes at various periods, so that a vast number must have been exhibited. No doubt the difference between many of the varieties is very small; but Mr. Thompson in classifying the fruit for the Horticultural Society found less confusion in the nomenclature of the gooseberry than of any other fruit, and he attributes this “to the great interest which the prize-growers have taken in detecting sorts with wrong names,” and this shows that all the kinds, numerous as they are, can be recognised with certainty.
The bushes differ in their manner of growth, being erect, or spreading, or pendulous. The periods of leafing and flowering differ both absolutely and relatively to each other; thus the Whitesmith produces early flowers, which from not being protected by the foliage, as it is believed, continually fail to produce fruit.[[122]] The leaves vary in size, tint, and in depth of lobes; they are smooth, downy, or hairy on the upper surface. The branches are more or less downy or spinose; “the Hedgehog has probably derived its name from the singular bristly condition of its shoots and fruit.” The branches of the wild gooseberry, I may remark, are smooth, with the exception of thorns at the bases of the buds. The thorns themselves are either very small, few and single, or very large and triple; they are sometimes reflexed and much dilated at their bases. In the different varieties the fruit varies in abundance, in the period of maturity, in hanging until shrivelled, and greatly in size, “some sorts having their fruit large during a very early period of growth, whilst others are small, until nearly ripe.” The fruit varies also much in colour, being red, yellow, green, and white—the pulp of one dark-red gooseberry being tinged with yellow; in flavour; in being smooth or downy,—few, however, of the Red gooseberries, whilst many of the so-called Whites, are downy; or in being so spinose that one kind is called Henderson’s Porcupine. Two kinds acquire when mature a powdery bloom on their fruit. The fruit varies in the thickness and veining of the skin, and, lastly, in shape, being spherical, oblong, oval, or obovate.[[123]]
I cultivated fifty-four varieties, and, considering how greatly the fruit differs, it was curious how closely similar the flowers were in all these kinds. In only a few I detected a trace of difference in the size or colour of the corolla. The calyx differed in a rather greater degree, for in some kinds it was much redder than in others; and in one smooth white gooseberry it was unusually red. The calyx also differed in the basal part being smooth or woolly, or covered with glandular hairs. It deserves notice, as being contrary to what might have been expected from the law of correlation, that a smooth red gooseberry had a remarkably hairy calyx. The flowers of the Sportsman are furnished with very large coloured bracteæ; and this is the most singular deviation of structure which I have observed. These same flowers also varied much in the number of the petals, and occasionally in the number of the stamens and pistils; so that they were semi-monstrous in structure, yet they produced plenty of fruit. Mr. Thompson remarks that in the Pastime gooseberry “extra bracts are often attached to the sides of the fruit.”[[124]]
The most interesting point in the history of the gooseberry is the steady increase in the size of the fruit. Manchester is the metropolis of the fanciers, and prizes from five shillings to five or ten pounds are yearly given for the heaviest fruit. The ‘Gooseberry Growers Register’ is published annually; the earliest known copy is dated 1786, but it is certain that meetings for the adjudication of prizes were held some years previously.[[125]] The ‘Register’ for 1845 gives an account of 171 Gooseberry Shows, held in different places during that year; and this fact shows on how large a scale the culture has been carried on. The fruit of the wild gooseberry is said[[126]] to weigh about a quarter of an ounce or 5 dwts., that is, 120 grains; about the year 1786 gooseberries were exhibited weighing 10 dwts., so that the weight was then doubled; in 1817 26 dwts. 17 grs. was attained; there was no advance till 1825, when 31 dwts. 16 grs. was reached; in 1830 “Teazer” weighed 32 dwts. 13 grs.; in 1841 “Wonderful” weighed 32 dwts. 16 grs.; in 1844 “London” weighed 35 dwts. 12 grs., and in the following year 36 dwts. 16 grs.; and in 1852 in Staffordshire, the fruit of the same variety reached the astonishing weight of 37 dwts. 7 grs.[[127]] or 896 grs.; that is, between seven or eight times the weight of the wild fruit. I find that a small apple, 6½ inches in circumference, has exactly this same weight. The “London” gooseberry (which in 1852 had altogether gained 333 prizes) has, up to the present year of 1875, never reached a greater weight than that attained in 1852. Perhaps the fruit of the gooseberry has now reached the greatest possible weight, unless in the course of time some new and distinct variety shall arise.
This gradual, and on the whole steady increase of weight from the latter part of the last century to the year 1852, is probably in large part due to improved methods of cultivation, for extreme care is now taken; the branches and roots are trained, composts are made, the soil is mulched, and only a few berries are left on each bush;[[128]] but the increase no doubt is in main part due to the continued selection of seedlings which have been found to be more and more capable of yielding such extraordinary fruit. Assuredly the “Highwayman” in 1817 could not have produced fruit like that of the “Roaring Lion” in 1825; nor could the “Roaring Lion,” though it was grown by many persons in many places, gain the supreme triumph achieved in 1852 by the “London” Gooseberry.
Walnut (Juglans regia).—This tree and the common nut belong to a widely different order from the foregoing fruits, and are therefore here noticed. The walnut grows wild on the Caucasus and in the Himalaya, where Dr. Hooker[[129]] found the fruit of full size, but “as hard as a hickory-nut.” It has been found fossil, as M. de Saporta informs me, in the tertiary formation, of France.
In England the walnut presents considerable differences, in the shape and size of the fruit, in the thickness of the husk, and in the thinness of the shell; this latter quality has given rise to a variety called the thin-shelled, which is valuable, but suffers from the attacks of tit-mice.[[130]] The degree to which the kernel fills the shell varies much. In France there is a variety called the Grape or cluster-walnut, in which the nuts grow in “bunches of ten, fifteen, or even twenty together.” There is another variety which bears on the same tree differently shaped leaves, like the heterophyllous hornbeam; this tree is also remarkable from having pendulous branches, and bearing elongated, large, thin-shelled nuts.[[131]] M. Cardan has minutely described[[132]] some singular physiological peculiarities in the June-leafing variety, which produces its leaves and flowers four or five weeks later than the common varieties; and although in August it is apparently in exactly the same state of forwardness as the other kinds, it retains its leaves and fruit much later in the autumn. These constitutional peculiarities are strictly inherited. Lastly, walnut-trees, which are properly monoicous, sometimes entirely fail to produce male flowers.[[133]]
Nuts (Corylus avellana).—Most botanists rank all the varieties under the same species, the common wild nut.[[134]] The husk, or involucre, differs greatly, being extremely short in Barr’s Spanish, and extremely long in filberts, in which it is contracted so as to prevent the nut falling out. This kind of husk also protects the nut from birds, for titmice (Parus) have been observed [[135]] to pass over filberts, and attack cobs and common nuts growing in the same orchard. In the purple-filbert the husk is purple, and in the frizzled-filbert it is curiously laciniated; in the red-filbert the pellicle of the kernel is red. The shell is thick in some varieties, but is thin in Cosford’s-nut, and in one variety is of a bluish colour. The nut itself differs much in size and shape, being ovate and compressed in filberts, nearly round and of great size in cobs and Spanish nuts, oblong and longitudinally striated in Cosford’s, and obtusely four-sided in the Downton Square nut.
Cucurbitaceous plants.—These plants have been for a long period the opprobrium of botanists; numerous varieties have been ranked as species, and, what happens more rarely, forms which now must be considered as species have been classed as varieties. Owing to the admirable experimental researches of a distinguished botanist, M. Naudin,[[136]] a flood of light has recently been thrown on this group of plants. M. Naudin, during many years, observed and experimented on above 1200 living specimens, collected from all quarters of the world. Six species are now recognised in the genus Cucurbita; but three alone have been cultivated and concern us, namely, C. maxima and pepo, which include all pumpkins, gourds, squashes, and the vegetable marrow, and C. moschata. These three species are not known in a wild state; but Asa Gray[[137]] gives good reason for believing that some pumpkins are natives of N. America.
These three species are closely allied, and have the same general habit, but their innumerable varieties can always be distinguished, according to Naudin, by certain almost fixed characters; and what is still more important, when crossed they yield no seed, or only sterile seed; whilst the varieties spontaneously intercross with the utmost freedom. Naudin insists strongly (p. 15), that, though these three species have varied greatly in many characters, yet it has been in so closely an analogous manner that the varieties can he arranged in almost parallel series, as we have seen with the forms of wheat, with the two main races of the peach, and in other cases. Though some of the varieties are inconstant in character, yet others, when grown separately under uniform conditions of life, are, as Naudin repeatedly (pp. 6, 16, 35) urges, “douées d’une stabilité presque comparable à celle des espèces les mieux caractérisées.” One variety, l’Orangin (pp. 43, 63), has such prepotency in transmitting its character, that when crossed with other varieties a vast majority of the seedlings come true. Naudin, referring (p. 47) to C. pepo, says that its races “ne different des espèces veritables qu’en ce qu’elles peuvent s’allier les unes aux autres par voie d’hybridité, sans que leur descendance perde la faculté de se perpétuer.” If we were to trust to external differences alone, and give up the test of sterility, a multitude of species would have to be formed out of the varieties of these three species of Cucurbita. Many naturalists at the present day lay far too little stress, in my opinion, on the test of sterility; yet it is not improbable that distinct species of plants after a long course of cultivation and variation may have their mutual sterility eliminated, as we have every reason to believe has occurred with domesticated animals. Nor, in the case of plants under cultivation, should we be justified in assuming that varieties never acquire a slight degree of mutual sterility, as we shall more fully see in a future chapter when certain facts are given on the high authority of Gärtner and Kölreuter.[[138]]
The forms of C. pepo are classed by Naudin under seven sections, each including subordinate varieties. He considers this plant as probably the most variable in the world. The fruit of one variety (pp. 33, 46) exceeds in value that of another by more than two thousand fold! When the fruit is of very large size, the number produced is few (p. 45); when of small size, many are produced. No less astonishing (p. 33) is the variation in the shape of the fruit, the typical form apparently is egg-like, but this becomes either drawn out into a cylinder, or shortened into a flat disc. We have also an almost infinite diversity in the colour and state of surface of the fruit, in the hardness both of the shell and of the flesh, and in the taste of the flesh, which is either extremely sweet, farinaceous, or slightly bitter. The seeds also differ in a slight degree in shape, and wonderfully in size (p. 34), namely, from six or seven to more than twenty-five millimètres in length.
In the varieties which grow upright or do not run and climb, the tendrils, though useless (p. 31), are either present or are represented by various semi-monstrous organs, or are quite absent. The tendrils are even absent in some running varieties in which the stems are much elongated. It is a singular fact that (p. 31) in all the varieties with dwarfed stems, the leaves closely resemble each other in shape.
Those naturalists who believe in the immutability of species often maintain that, even in the most variable forms, the characters which they consider of specific value are unchangeable. To give an example from a conscientious writer,[[139]] who, relying on the labours of M. Naudin, and referring to the species of Cucurbita, says, “au milieu de toutes les variations du fruit, les tiges, les feuilles, les calices, les corolles, les étamines restent invariables dans chacune d’elles.” Yet M. Naudin, in describing Cucurbita pepo (p. 30), says, “Ici, d’ailleurs, ce ne sont pas seulement les fruits qui varient, c’est aussi le feuillage et tout le port de la plante. Néanmoins, je crois qu’on la distinguera toujours facilement des deux autres espèces, si l’on veut ne pas perdre de vue les caractères différentiels que je m’efforce de faire ressortir. Ces caractères sont quelquefois peu marqués: il arrive meme que plusieurs d’entre eux s’effacent presque entièrement, mais ii en reste toujours quelques-uns qui remettent l’observateur sur la voie.” Now let it be noted what a difference, with regard to the immutability of the so-called specific characters this paragraph produces on the mind, from that above quoted from M. Godron.
I will add another remark: naturalists continually assert that no important organ varies; but in saying this they unconsciously argue in a vicious circle; for if an organ, let it be what it may, is highly variable, it is regarded as unimportant, and under a systematic point of view this is quite correct. But as long as constancy is thus taken as the criterion of importance, it will indeed be long before an important organ can be shown to be inconstant. The enlarged form of the stigmas, and their sessile position on the summit of the ovary, must be considered as important characters, and were used by Gasparini to separate certain pumpkins as a distinct genus; but Naudin says (p. 20), these parts have no constancy, and in the flowers of the Turban varieties of C. maxima they sometimes resume their ordinary structure. Again, in C. maxima, the carpels (p. 19) which form the turban project even as much as two-thirds of their length out of the receptacle, and this latter part is thus reduced to a sort of platform; but this remarkable structure occurs only in certain varieties, and graduates into the common form in which the carpels are almost entirely enveloped within the receptacle. In C. moschata the ovarium (p. 50) varies greatly in shape, being oval, nearly spherical, or cylindrical, more or less swollen in the upper part, or constricted round the middle, and either straight or curved. When the ovarium is short and oval the interior structure does not differ from that of C. maxima and pepo, but when it is elongated the carpels occupy only the terminal and swollen portion. I may add that in one variety of the cucumber (Cucumis sativus) the fruit regularly contains five carpels instead of three.[[140]] I presume that it will not be disputed that we here have instances of great variability in organs of the highest physiological importance, and with most plants of the highest classificatory importance.
Sageret[[141]] and Naudin found that the cucumber (C. sativus) could not be crossed with any other species of the genus; therefore no doubt it is specifically distinct from the melon. This will appear to most persons a superfluous statement; yet we hear from Naudin[[142]] that there is a race of melons, in which the fruit is so like that of the cucumber, “both externally and internally, that it is hardly possible to distinguish the one from the other except by the leaves.” The varieties of the melon seem to be endless, for Naudin after six years’ study had not come to the end of them: he divides them into ten sections, including numerous sub-varieties which all intercross with perfect ease.[[143]] Of the forms considered by Naudin to be varieties, botanists have made thirty distinct species! “and they had not the slightest acquaintance with the multitude of new forms which have appeared since their time.” Nor is the creation of so many species at all surprising when we consider how strictly their characters are transmitted by seed, and how wonderfully they differ in appearance: “Mira est quidem foliorum et habitus diversitas, sed multo magis fructuum,” says Naudin. The fruit is the valuable part, and this, in accordance with the common rule, is the most modified part. Some melons are only as large as small plums, others weigh as much as sixty-six pounds. One variety has a scarlet fruit! Another is not more than an inch in diameter, but sometimes more than a yard in length, “twisting about in all directions like a serpent.” It is a singular fact that in this latter variety many parts of the plant, namely, the stems, the footstalks of the female flowers, the middle lobe of the leaves, and especially the ovarium, as well as the mature fruit, all show a strong tendency to become elongated. Several varieties of the melon are interesting from assuming the characteristic features of distinct species and even of distinct though allied genera: thus the serpent-melon has some resemblance to the fruit of Trichosanthes anguina; we have seen that other varieties closely resemble cucumbers; some Egyptian varieties have their seeds attached to a portion of the pulp, and this is characteristic of certain wild forms. Lastly, a variety of melon from Algiers is remarkable from announcing its maturity by “a spontaneous and almost sudden dislocation,” when deep cracks suddenly appear, and the fruit falls to pieces; and this occurs with the wild C. momordica. Finally, M. Naudin well remarks that this “extraordinary production of races and varieties by a single species and their permanence when not interfered with by crossing, are phenomena well calculated to cause reflection.”