In a remarkable field of “natural selection” Bates, Wallace and Poulton have explained the value of “mimicry” as an aid to beasts, birds, insects, as they elude their enemies or lie unsuspected on the watch for prey. The resemblances thus worked out through successive generations attest the astonishing plasticity of bodily forms, a plasticity which would be incredible were not its evidence under our eyes in every quarter of the globe. Insects have high economic importance as agents of destruction: we are learning how to pit one of them against another, so as to leave a clear field to the farmer and the fruit grower. In this department a leader is Professor Howard, who contributes a noteworthy chapter on the successful fight against the pest which threatened with ruin the orange groves of California.
To the every-day observer the most enticing field of natural history is that in which common flowers and common insects work out their unending co-partnery. A blossom by its scent, its beauty of tint, allures a moth or bee and thus, in effect, is able to take flight and find a mate across a county so as to perpetuate its race a hundred miles from home. Our volume closes with a sketch of the singular ties which thus bind together the fortunes of blossom and insect, so that at last the very form of a flower may be cast in the mould of its winged ally. A word is also spoken regarding the singular relations of late detected between the world of vegetation and minute forms once deemed parasitic. The pea and its kindred harbor on their rootlets certain tiny lodgers; the tenants pay a liberal rent in the form of nitrogen compounds, a striking interlacement of interests!
George Iles.
CONTENTS
| DARWIN, CHARLES | |
| [The Origin of Species in Summary] | |
Varieties merge gradually into species. Animals tend toincrease in geometrical ratio. Varieties diverge in consonancewith diversity of opportunity for life. In the strugglefor existence those which best accord with their surroundingswill survive and propagate their kind. Sexual selectionhas put a premium on beauty. The causes which in briefperiods produce varieties, in long periods give rise tospecies. Instincts, as of the hive bee, are slowly developed.Geology supports the theory of Evolution: the changes in timein the fossil record are gradual. Geographical distributionlends its corroboration: in each region most of the inhabitantsin every great class are plainly related. A common ancestoris suggested when we see the similarity of hand, wing andfin. Embryos of birds, reptiles and fish are closely similarand unlike adult forms. Slight changes in the course ofmillions of years produce wide divergences. | [3] |
| DARWIN, CHARLES | |
| [How “The Origin of Species” Came to be Written] | |
During his voyage on the Beagle Darwin saw fossilarmadillos like existing species, and on the islands of theGalapagos group a gradually increased diversity of species ofevery kind. All this suggested that species gradually becomemodified. Notes gathered of facts bearing on the question.Observes that it is the variation between one animal andanother which gives the breeder his opportunity. ReadsMalthus on Population, a work which points out the keenstruggle for existence and that favourable variations tend tobe preserved. In 1842 draws up a brief abstract of the theoryof “natural selection.” In 1856 begins an elaborate work onthe same theme, but in 1858, hearing that Wallace has writtenan essay advancing an independent theory of natural selection,offers a summary of his argument to the Linnean Societyof London. Writes “The Origin of Species,” which is publishedmost successfully, November, 1859. | [35] |
| DARWIN, CHARLES | |
| [The Descent of Man: the Argument in Brief] | |
Since evolution is probable for all other animals, it isprobable for man. The human form has so much in common withthe forms of other animals that community of descent isstrongly suggested. Man, like other creatures, is subject tothe struggle for existence. Evidence shows that it is likelythat man is descended from a tailed and hairy quadruped thatdwelt in trees. Man's mental power has been the chief factorin his advance, especially in his development of language.Conscience is due to social instincts, love of approbation,memory, imagination and religious feeling. Sexual selectionin its effects upon human advancement. | [45] |
| WALLACE, ALFRED R. | |
| [Mimicry and Other Protective Resemblances Among Animals] | |
The colours of animals are useful for concealment from theirprey, from the creatures upon which they prey. The lion isscarcely visible as he crouches on the sand or among desertrocks and stones. Larks, quails and many other birds are sotinted and mottled that their detection is difficult. Thepolar bear, living amid ice and snow, is white. Reptiles andfish are so coloured as to be almost invisible in the grassor gravel where they rest. Many beetles and other insectsare so like the leaves or bark on which they feed thatwhen motionless they cannot be discerned. Some butterfliesresemble dead, dry or decaying leaves so closely as to eludediscovery. Every individual better protected by colour thanothers, has a better chance for life, and of transmitting hishues. Harmless beetles and flies are so like wasps and beesas to be left alone. | [71] |
| HUXLEY, THOMAS H. | |
| [Evolution of the Horse] | |
The hoof of the horse is simply a greatly enlarged andthickened nail: four of his five toes are reduced to merevestiges. His teeth are built of substances of varyinghardness: they wear away at different rates presenting unevengrinding surfaces. Probable descent of the horse, link bylink, especially as traced in the fossils of North America.Evolution has taken a long time: how long the physicist andthe astronomer must decide. | [101] |
| HOWARD, LELAND O. | |
| [Fighting Pests with Insect Allies] | |
A scale insect threatened with ruin the orchards of California.Professor C. V. Riley decided that the pest was a nativeof Australia. Mr. A. Hoebele observes in Australia thatthe pest is kept down by ladybirds. These are accordinglysent to California where they destroy the scale insect andrestore prosperity among the fruit-growers. Another pest,of olive trees, is devoured by an imported ladybird ofanother species. This plan extended to Portugal and Egyptwith success. Grasshoppers killed by a fungus cultivatedfor the purpose. Introduction into the United States ofthe insect which fertilizes the Smyrna fig. | [123] |
| ILES, GEORGE | |
| [The Strange Story of the Flowers: a Chapter in Modern Botany] | |
Dress is important, whether natural or artificial. Becausethey catch dust on their clothes, bees, moths and butterflieshave brought about myriad espousals of flower with flower.Colours and scents of blossoms attract insects. A flowerwhich in form, scent or hue varies gainfully is likely tosurvive while others perish. All the parts of a flower areleaves in disguise. Floral modes of repulsion and defence.Plants which devour insects, a habit gradually acquired. Themesquit tree tells of water. Plants believed to indicatemineral veins. Seeds as emigrants equipped with wings orhooks. Parasitic plants and their degradation. Tenants thatpay a liberal rent. The gardener as a creator of new flowers.The modern sugar beet due to Mons. Vilmorin. | [139] |