manifested in the higher forms of life? By transitory changes of parts, which are due to the property of contractility. The power of movement in all the animal grades resolves itself into this: 'Even those manifestations of intellect, of feeling, and of will, which we rightly name the higher faculties, are not excluded from this classification, inasmuch as (to every one but the subject of them) they are known only as transitory changes in the relative positions of different parts of the body. Speech, gesture, and every other form of human action, are, in the long run, resolvable into muscular contractions.'
"But this property of contractility is also manifested in plants, and in protoplasm itself. 'So far as the conditions of the manifestation of the phenomena of contractility have yet been studied, they, are the same for the plant as for the animal. Heat and electric shocks influence both and in the same way, though it may be in different degrees. It is by no means my intention to suggest that there is no difference in faculty between the lowest plant and the highest, or between plants and animals. But the difference between the powers of the lowest plant or animal and the highest is one of degree, not of kind, and depends, as Milne-Edward long ago so well pointed out, upon the extent to which the division of labor is carried out in the living economy.'
"The following graphic passages present a vivid picture of the extent and regularity of protoplasmic movements:—
"'I am not now alluding to such phenomena, at once rare and conspicuous, as those exhibited by the leaflets of the sensitive-plant, or the stamens of the barberry, but to much more widely spread, and, at the same time, move subtle and hidden, manifestations of vegetable contractility. You are doubtless aware that the common nettle owes its stinging property to the innumerable stiff and needle-like, though exquisitely delicate, hairs which cover its surface. Each stinging-needle tapers from a broad base to a slender summit, which, though rounded at the end, is of such microscopic fineness that it readily penetrates, and breaks off in, the skin. The whole hair consists of a very delicate outer case of wood, closely applied to the inner surface of which is a layer of semi-fluid matter, full of innumerable granules of extreme minuteness. This semi-fluid lining is protoplasm, which thus constitutes a kind of bag, full of a limpid liquid, and roughly
