[3] p. 4.—“Their rotating bodies.”
Fontana, in his excellent work “Über das Viperngift,” Bd. i. S. 62, relates that he succeeded, in the course of two hours, by means of a drop of water, in bringing to life a rotifera which had lain for two years and a half dried up and motionless. On the action and effect of water, see my “Versuche über die gereizte Muskel- und Nervenfaser,” Bd. ii. S. 250.
What has been called the revivification of Rotiferæ, since observations have been more exact and have had to undergo stricter criticism, has been the subject of much animated discussion. Baker affirmed that he had resuscitated, in 1771, paste-eels which Needham had given him in 1744! Franz Bauer saw his Vibrio tritici, which had been dried up for four years, move again on being moistened. An extremely careful and experienced observer, Doyère, in his Mémoire sur les Tardigrades, et sur leur propriété de revenir à la vie (1842), draws from his own fine experiments the following conclusions:—Rotiferæ come to life, i. e. pass from a motionless state to a state of motion, after having been exposed to temperatures of 19°.2 Reaumur below, and 36° Reaumur above, the freezing point; i. e. from 11°.2 to 113°.0 Fah. They preserve the capability of apparent revivification, in dry sand, up to 56°.4 R. (158°.9 Fah.); but they lose it, and cannot be excited afresh, if heated in moist sand to 44° only (131°.0 Fah.) Doyère, p. 119. The possibility of revivification or reanimation is not prevented by their being placed for twenty-eight days in barometer tubes in vacuo, or even by the application of chloride of lime or sulphuric acid (pp. 130-133). Doyère has also seen the rotiferæ come to life again very slowly after being dried without sand (desséchés à nu), which Spallanzani had denied (pp. 117 and 129). “Toute dessiccation faite à la température ordinaire pourroit souffrir des objections auxquelles l’emploi du vide sec n’eût peut-être pas complètement repondu: mais en voyant les Tardigrades périr irrévocablement à une température de 44°, si leurs tissus sont pénétrés d’eau, tandis que desséchés ils supportent sans périr une chaleur qu’on peut évaluer a 96° Reaumur, on doit être disposé à admettre que la revivification n’a dans l’animal d’autre condition que l’intégrité de composition et de connexions organiques.” In the same way, in the vegetable kingdom, the sporules of cryptogamia, which Kunth compares to the propagation of certain phænogamous plants by buds (bulbillæ), retain their germinating power in the highest temperatures. According to the most recent experiments of Payen, the sporules of a minute fungus (Oïdium aurantiacum), which covers the crumb of bread with a reddish feathery coating, do not lose their power of germination by being exposed for half an hour in closed tubes to a temperature of from 67° to 78° Reaumur (182°.75 to 207°.5 Fah.), before being strewed on fresh perfectly unspoilt dough. May not the newly discovered monad (Monas prodigiosa), which causes blood-like spots on mealy substances, have been mingled with this fungus?
Ehrenberg, in his great work on Infusoria (S. 492-496), has given the most complete history of all the investigations which have taken place on what is called the revivification of rotiferæ. He believes that, in spite of all the means of desiccation employed, the organization-fluid still remains in the apparently dead animal. He contests the hypothesis of “latent life;” death, he says, is not “life latent, but the want of life.”
We have evidence of the diminution, if not of the entire disappearance or suspension of organic functions, in the hybernation or winter sleep both of warm and cold-blooded animals, in the dormice, marmots, sand martins (Hirundo riparia) according to Cuvier (Règne animal, 1829, T. i. p. 396), frogs and toads. Frogs, awakened from winter-sleep by warmth, can support an eight times’ longer stay under water without being drowned, than frogs in the breeding season. It would seem as if the functions of the lungs in respiration, for some time after their excitability had been suspended, required a less degree of activity. The circumstance of the sand-martin sometimes burying itself in a morass is a phenomenon which, while it seems not to admit of doubt, is the more surprising, as in birds respiration is so extremely energetic, that, according to Lavoisier’s experiments, two small sparrows, in their ordinary state, decomposed, in the same space of time, as much atmospheric air as a porpoise. (Lavoisier, Mémoires de Chimie, T. i. p, 119.) The winter-sleep of the swallow in question (the Hirundo riparia) is not supposed to belong to the entire species, but only to have been observed in some individuals. (Milne Edwards, Elémens de Zoologie, 1834, p. 543.)
As in the cold zone the deprivation of heat causes some animals to fall into winter-sleep, so the hot tropical countries afford an analogous phænomenon, which has not been sufficiently attended to, and to which I have applied the name of summer-sleep. (Relation historique, T. ii. pp. 192 and 626.) Drought and continuous high temperatures act like the cold of winter in diminishing excitability. In Madagascar, (which, with the exception of a very small portion at its southern extremity, is entirely within the tropical zone,) as Bruguière had before observed, the hedgehog-like Tenrecs (Centenes, Illiger), one species of which (C. ecaudatus) has been introduced into the Isle of France, sleep during great heat. Desjardins makes, it is true, the objection that the time of their slumber is the winter season of the southern hemisphere; but in a country in which the mean temperature of the coldest month is 3° Reaumur (6°.75 Fah.) above that of the hottest month in Paris, this circumstance cannot change the three months’ “summer-sleep” of the Tenrec in Madagascar and at Port Louis, into what we understand by a winter-sleep, or state of hybernation.
In the hot and dry season, the crocodile in the Llanos of Venezuela, the land and water tortoises of the Orinoco, the huge boa, and several smaller kinds of serpents, become torpid and motionless, and lie incrusted in the indurated soil. The missionary Gili relates that the natives, in seeking for the slumbering Terekai (land tortoises), which they find lying at a depth of sixteen or seventeen inches in dried mud, are sometimes bitten by serpents which become suddenly aroused, and which had buried themselves at the same time as the tortoise. An excellent observer, Dr. Peters, who has just returned from the East Coast of Africa, writes thus to me on the subject:—“During my short stay at Madagascar I could obtain no certain information respecting the Tenrec; but, on the other hand, I know that in the East of Africa, where I lived for several years, different kinds of tortoises (Pentonyx and Trionchydias) pass months during the dry season of this tropical country inclosed in the dry hard earth, and without food. The Lepidosiren also, in places where the swamps are dried up, remains coiled up and motionless, encased in indurated earth, from May to December.”
Thus we find an annual enfeeblement of certain vital functions in many and very different classes of animals, and, what is particularly striking, without the same phenomena being presented by other living creatures nearly allied to them, and belonging to the same family. The northern glutton (Gulo), though allied to the badger (Meles), does not like him sleep during the winter; whereas, according to Cuvier’s remark, “a Myoxus (dormouse) of Senegal (Myoxus coupeii), which could never have known winter-sleep in his tropical home, being brought to Europe fell asleep the first year on the setting in of winter.” This torpidity or enfeeblement of the vital functions and vital activity passes through several gradations, according as it extends to the processes of nutrition, respiration, and muscular motion, or to depression of the activity of the brain and nervous system. The winter-sleep of the solitary bears and of the badger is not accompanied by any rigidity, and hence the reawakening of these animals is so easy, and, as was often related to me in Siberia, so dangerous to the hunters and country people. The first recognition of the gradation and connection of these phenomena leads us up to what has been called the “vita minima” of the microscopic organisms, which, occasionally with green ovaries and undergoing the process of spontaneous division, fall from the clouds in the Atlantic sand-rain. The apparent revivification of rotiferæ, as well as of the siliceous-shelled infusoria, is only the renewal of long-enfeebled vital functions,—a state of vitality which was never entirely extinct, and which is fanned into a fresh flame, or excited anew, by the appropriate stimulus. Physiological phenomena can only be comprehended by being traced throughout the entire series of analogous modifications.
[4] p. 5.—“Winged insects.”
Formerly the fertilization of flowers in which the sexes are separated was ascribed principally to the action of the wind: it has been shown by Kölreuter, and with great ingenuity by Sprengel, that bees, wasps, and a host of smaller winged insects, are the chief agents. I say the chief agents, because to assert that no fertilization is possible without the intervention of these little animals appears to me not to be in conformity with nature, as indeed has been shown in detail by Willdenow. (Grundriss der Kräuterkunde, 4te Aufl., Berl. 1805, S. 405-412.) On the other hand, Dichogamy, coloured spots or marks indicating honey-vessels (maculæ indicantes), and fertilization by insects, are, in much the greater number of cases, inseparably associated. (Compare Auguste de St. Hilaire, Leçons de Botanique, 1840, p. 565-571.)