"Enough has, perhaps, been said to prove the existence of a general uniformity in the character of the protoplasm, or physical basis of life, in whatever group of living beings it may be studied. But it will be understood that this general uniformity by no means excludes any amount of special modifications of the fundamental substance. The mineral, carbonate of lime, assumes an immense diversity of characters, though no one doubts that under all these protean changes it is one and the same thing. And now, what is the ultimate fate, and what the origin, of the matter of life? Is it, as some of the older naturalists supposed, diffused throughout the universe in molecules, which are indestructible and unchangeable in themselves; but, in endless transmigration, unite in innumerable permutations, into the diversified forms of life we know? Or is the matter of life composed of ordinary matter, differing from it only in the manner in which its atoms are aggregated. Is it built up of ordinary matter, and again resolved into ordinary matter when its work is done? Modern science does not hesitate a moment between these alternatives. Physiology writes over the portals of life,
'Debemur morti nos nostraque,'
with a profounder meaning than the Roman poet attached to that melancholy line. Under whatever disguise it takes refuge, whether fungus or oak, worm or man, the living protoplasm not only ultimately dies and is resolved into its mineral and lifeless constituents, but is always dying, and, strange as the paradox may sound, could not live unless it died."
Suppose all this to be precisely as asserted, it only proves that there is diffused through the whole material world elements which in certain unknown and inexplicable combinations, afford sustenance to plants, and through plants to animals, or from which the living organism repairs its waste and sustains its life. It does not tell us how carbon, hydrogen, oxygen, and nitrogen are or must be combined to form the alleged protoplasm, whence is the living organism, nor the origin or principle of its life. It, in fact, shows us neither the origin nor the matter of life, for it is only an actually living organism that uses or assimilates the alleged protoplasm. There is evidently at work in the organism a vital force that is distinguishable from the irritability or contractility of the protoplasm, and not derived from or originated by it. Undoubtedly, every organism that falls under our observation, whether vegetable or animal, has its physical conditions, and lives by virtue of a physical law; but this, even when we have determined the law and ascertained the conditions, throws no light on the life itself. The life escapes all observation, and science is impotent, if it leaves out the creative act of God, to explain it, or to bring us a step nearer its secret. Professor Huxley tells us no more, with all his science and hard words, than any cultivator of the soil, any shepherd or herdsman, can tell us, and knows as well as he, as we have already said.
In the last extract, the professor evidently prefers, of the two alternatives he suggests, the one that asserts that "the matter of life [protoplasm] is composed of ordinary matter, is built up of ordinary matter, and resolved again into ordinary matter when its work is done." This the professor applies to man as well as to plants and animals. Hence, he cites the Roman poet,
"Debemur morti nos nostraque."
But we have conceded the professor more than he asks. We have conceded that all matter is, in a certain sense, plastic, and living, in the sense of being active, not passive. But the professor does not ask so much. We inferred from some things in the beginning of his discourse that he intended to maintain that his protoplasm is itself elemental, and pervading all nature. But this is not the case; he merely holds it to be a chemical compound formed by the peculiar chemical combination of lifeless components. Thus he says:
"But it will be observed that the existence of the matter of life depends on the pre-existence of certain compounds, namely, carbonic acid, water, and ammonia. Withdraw any one of these three from the world, and all vital phenomena come to an end. They are related to the protoplasm of the plant, as the protoplasm of the plant is to that of the animal. Carbon, hydrogen, oxygen, and nitrogen are all lifeless bodies. Of these, carbon and oxygen unite in certain proportions 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 my secular 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."
But here is a break or a bold leap from a lifeless to a living compound. No matter how different are the several chemical compounds known from the simple components, the new compound is always, as far as known, as lifeless as were the several components themselves. Hydrogen and oxygen compounded give rise to water, but water is lifeless. Hydrogen and nitrogen, brought together in certain proportions, give rise to ammonia, still a lifeless compound. No chemist has yet, by any combination of the minerals, carbon, hydrogen, oxygen, and nitrogen, the constituents of protoplasm, been able to produce a living plant or a living organism of any sort. How then conclude that their combination produces the matter of life, or gives rise to the living organism? There seems to us to be a great gulf between the premises and the conclusion. Certain combinations of carbon, hydrogen, oxygen, and nitrogen produce certain lifeless compounds different from themselves, therefore a certain other combination of these same elements produces the living organism, plant, or animal, or originates the matter, and forms the physical basis of life. If the professor had in his school days reasoned in this way, his logic-master, we suspect, would have set a black mark against his name, or, more likely, have rapped him over the knuckles, if not over his head, and told him that an argument that has no middle term, is no argument at all, and that "Transitio a genere ad genus," as from the lifeless to the living, is a sophism.