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What cruel hand hath snatched my blooms away?

The sullen, silver-rifted sky looks down Between grey branches, -not a golden gleam

Some called it sad, some said 'twas glad - Falls on the scanty leaves, grown sere and

ON THE BORDER TERRITORY BETWEEN
THE ANIMAL AND THE VEGETABLE

KINGDOMS.

From Macmillan's Magazine. to undergo, before it can be converted into substances fitted for absorption; while the atmosphere and the earth supply plants with juices ready prepared, and which can be absorbed immediately.

BY T. H. HUXLEY.

IN the whole history of science there is nothing more remarkable than the rapidity of the growth of biological knowledge within the last half-century, and the extent of the modification which has thereby been effected in some of the fundamental conceptions of the naturalist.

As the animal body required to be independent of heat and of the atmosphere, there were no means by which the motion of its fluids could be produced by internal causes. Hence arose the second great distinctive character of animals, or the circulatory system, which is less important than the digestive, since it was unnecessary, and therefore is absent, in the more simple animals.

Animals further needed muscles for lo

comotion and nerves for sensibility. Hence, says Cuvier, it was necessary that

In the second edition of the "Règne Animal," published in 1828, Cuvier devotes a special section to the "Division of Organized Beings into Animals and Vegetables," in which the question is treated with that comprehensiveness of knowledge and clear critical judgment the chemical composition of the animal which characterize his writings, and justify us in regarding them as representative expressions of the most extensive, if not the profoundest, knowledge of his time. He tells us that living beings have been sub-divided from the earliest times into animated beings, which possess sense and motion, and inanimated beings, which are devoid of these functions, and simply vegetate.

Although the roots of plants direct themselves towards moisture, and their leaves towards air and light; although the parts of some plants exhibit oscillating movements without any perceptible cause, and the leaves of others retract when touched, yet none of these movements justify the ascription to plants of perception or of will.

body should be more complicated than that of the plant; and it is so, inasmuch as an additional substance, nitrogen, enters into it as an essential element, while in plants nitrogen is only accidentally joined with the three other fundamental constituents of organic beings carbon, hydrogen, and oxygen. Indeed, he afterwards affirms that nitrogen is pecul iar to animals; and herein he places the third distinction between the animal and the plant.

The soil and the atmosphere supply plants with water, composed of hydrogen and oxygen; air, consisting of nitrogen and oxygen; and carbonic acid, containing carbon and oxygen. They retain the hydrogen and the carbon, exhale the superfluous oxygen, and absorb little or no From the mobility of animals, Cuvier, nitrogen. The essential character of vegwith his characteristic partiality for teleo-etable life is the exhalation of oxygen, logical reasoning, deduces the necessity of which is effected through the agency of the existence in them of an alimentary cavity or reservoir of food, whence their nutrition may be drawn by the vessels, which are a sort of internal roots; and in the presence of this alimentary cavity he naturally sees the primary and the most important distinction between animals and plants.

Following out his teleological argument, Cuvier remarks that the organization of this cavity and its appurtenances must needs vary according to the nature of the aliment, and the operations which it has

light.

Animals, on the contrary, derive their nourishment either directly or indirectly from plants. They get rid of the superfluous hydrogen and carbon, and accumu late nitrogen.

The relations of plants and animals to the atmosphere are therefore inverse. The plant withdraws water and carbonic acid from the atmosphere, the animal contributes both to it. Respiration — that is, the absorption of oxygen and the exhalation of carbonic acid-is the specially

animal function of animals, and constitutes | animals; and, while in this condition, their their fourth distinctive character.

movements are, to all appearance, as spontaneous - as much the product of volition as those of such animals.

Thus wrote Cuvier in 1828. But in the fourth and fifth decades of this century, the greatest and most rapid revolution Hence the teleological argument for which biological science has ever under- Cuvier's first diagnostic character - the gone was effected by the application of presence in animals of an alimentary cavthe modern microscope to the investiga- ity, or internal pocket, in which they can tion of organic structure; by the introduc- carry about their nutriment, has broken tion of exact and easily manageable meth-down-so far, at least, as his mode of ods of conducting the chemical analysis of organic compounds; and finally, by the employment of instruments of precision for the physical measurement of the forces which are at work in the living economy. That the semi-fluid contents (which we now term protoplasm) of the cells of certain plants, such as the Chara, are in constant and regular motion, was made out by Bonaventura Corti a century ago; but the fact, important as it was, fell into oblivion, and had to be rediscovered by Treviranus in 1807. Robert Brown noted the more complex motions of the protoplasm in the cells of Tradescuntia in 1831; and now such movements of the living substance of plants are well-known to be some of the most widely prevalent phenomena of vegetable life.

Agardh, and other of the botanists of Cuvier's generation, who occupied themselves with the lower plants, had observed that, under particular circumstances, the contents of the cells of certain water-weeds were set free and moved about with considerable velocity, and with all the appearances of spontaneity, as locomotive bodies, which, from their similarity to animals of simple organization, were called " spores."

stating it goes. And with the advance of microscopic anatomy the universality of the fact itself among animals has ceased to be predicable. Many animals of even complex structure, which live parasitically within others, are wholly devoid of an alimentary cavity. Their food is provided for them, not only ready cooked but ready digested, and the alimentary canal, become superfluous, has disappeared. Again, the males of most rotifers have no digestive apparatus; as a German naturalist has remarked, they devote themselves entirely to the Minnedienst, and are to be reckoned among the few realizations of the Byronic ideal of a lover. Finally, amidst the lowest forms of animal life, the speck of gelatinous protoplasm, which constitutes the whole body, has no permanent digestive cavity or mouth, but takes in its food anywhere; and digests, so to speak, all over its body.

But although Cuvier's leading diagnosis of the animal from the plant will not stand a strict test, it remains one of the most constant of the distinctive characters of animals. And if we substitute for the possession of an alimentary cavity, the zoo-power of taking solid nutriment into the body and there digesting it, the definition so changed will cover all animals, except certain parasites, and the few and exceptional cases of non-parasitic animals which do not feed at all. On the other hand, the definition thus amended will exclude

Even as late as 1845, however, a botanist of Schleiden's eminence deals very sceptically with these statements; and his scepticism was the more justified, since Ehrenberg, in his elaborate and comprehensive work on the infusoria, had de-all ordinary vegetable organisms. clared the greater number of what are now recognized as locomotive plants to be animals.

At the present day, innumerable plants and free plant-cells are known to pass the whole or part of their lives in an actively locomotive condition, in no wise distinguishable from that of one of the simpler

Cuvier himself practically gives up his second distinctive mark when he admits that it is wanting in the simpler animals.

The third distinction is based on a completely erroneous conception of the chemical differences and resemblances between the constituents of animal and vegetable organisms, for which Cuvier is not re