the upper surface of the leaf which is susceptible of the peculiar effects of light. So it is only the optic nerve that is affected in a way which is necessary to vision. The sensitive plant contracts when touched ; and so does the animal muscle when the proper stimulus, nervous or electric, is applied. In short, as all the opera- tions of vegetable life are due to physical forces, so all the phenom- ena of animal life are due to the same causes.
On this subject Prof. Huxley says : " The matter of life is com- posed of ordinary matter, differing from it only in the manner in which its atoms are aggregated. It is built up of ordinary matter, and again resolved into ordinary matter when its woi'k is done." ^ By protoplasm, or matter of life, he sometimes means matter which exhibits the phenomena of life ; and sometimes, matter which hav- ing been elaborated by the plant or animal, is capable of support- ing life. Hence he calls boiled mutton protoplasm.
The only difference between inorganic, lifeless matter, and liv- ing plants or animals, is in the manner in which their atoms are aggregated. " Carbon, hydrogen, oxygen, and nitrogen, are all lifeless bodies. Of these, carbon and oxygen unite, in certain pro- portions, and under certain conditions, to give rise to carbonic acid ; hydrogen and oxygen produce water ; nitrogen and hydrogen give rise to ammonia. These new compounds, like the elementary bodies of which they are composed, are lifeless. But when they are brought together, under certain conditions they give rise to the still more complex body, protoplasm, and this protoplasm exhibits the phenomena of life. I see no break in this series of steps in molecular complication, and I am unable to understand why the language which is applicable to any one term of the series may not be used to any of the others When hydrogen and oxy- gen are mixed in a certain proportion, and an electric spark is passed through them, they disappear, and a quantity of water, equal in weight to the sum of their weights, appears in their place. There is not the' slightest parity between 'the passive and active powers of the water and those of the oxygen and hydrogen which have given rise to it."^ <-<■ What justification is there, then, for the assumption of the existence in the living matter of a something wliich has no representative, or correlative, in the not living mat- ter which gave rise to it ? What better philosophical status has * vitality ' than ' aquosity ? ' And why should ' vitality ' hope for a better fate than the other ' itys ' which have disappeax'ed since Martinus Scrlblerus accounted for the operation of the meat-jack 1 Lay Servwns, p. 144. 2 [bid. p. 149.
270 PART L — THEOLOGY. [Ch. IH. — Ajjti-Theism.
by its inherent ' meat-roasting quality,' and scorned the material- ism of those who explained the turning of the spit by a certain mech- anism worked by the draught of the chimney ? .... If the prop- erties of water may be properly said to result from the nature and disposition of its component molecules, I can find no intelligible ground for refusing to say that the properties of protoplasm result from the nature and disposition of its molecules." ^
The doctrine, therefore, is, that carbonic acid, water, and am- monia, lifeless bodies, under certain conditions, become living mat- ter, not in virtue of any ^ew force or principle communicated to them, but solely in virtue of a different arrangement of their mole- cules. Of this living matter all plants and animals are composed, and to the properties or physical forces inherent in the matter of which they are composed, all the phenomena of vegetable and ani- mal life are to be referred. " Pi'otoplasm," says Prof. Huxley, " is the clay of the potter : which, bake it and paint it as he will, re- mains clay, separated by artifice and not by nature, from the com- monest brick or sun-dried clod." ^ As the brick, no matter what its shape or color, can have no pi'operties not inherent in the clay, so vegetable or animal organisms can have no properties which do not belong to protoplasm, which, in the last analysis, is nothing but carbonic acid, water, and ammonia.
Professor Huxley is not only a distinguished naturalist, but a popular lecturer and preacher of "Lay Sermons," and thus has become a representative man among the advocates of this new form of Materialism. He is, however, very far from standing alone. " Some of the most distinguished living physicists, chemists, and naturalists," says Dr. Beale, " have accepted this physical theory of life. They liave taught that life is but a mode of ordinary force, and that the living thing differs from the non-living thing, not in quality, or essence, or kind, but merely in degree." ^ "So long," says the same writer, " as the advocates of the physical doctrine of life contented themselves with ridiculing ' vitality ' as a fiction and a myth, because it could not be made evident to the senses, measured or weighed, or proved scientifically to exist, their posi- tion was not easily assailed ; but now when they assert dogmati- cally that vital force is only a form or mode of ordinary motion, they are bound to show that the assertion rests upon evidence, or it will be regarded by thoughtful men as one of a large number of fanciful hypotheses, advocated only by those who desire to swell
1 Lay Sermons, p. 151. " Ibid. p. 142.
8 Protoplasm ; or Life, Matter, and Mind, by Lionel S. Beale, M. B., F. R. S. Second edition, London, 1870, p. 3.