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Though the concepts “vital force” and “life principle” have no standing in the court of modern biological science, it is interesting to observe how often recourse is had by biological writers to terms that embody the same idea. Thus the German physiologist Verworn, the determined enemy of the old conception of life, in his great work on “Irritability,” has recourse to “the specific energy of living substances.” One is forced to believe that without this “specific energy” his “living substances” would never have arisen out of the non-living.

Professor Moore, of Liverpool University, as I have already pointed out while discussing the term “vital force,” invents a new phrase, “biotic energy,” to explain the same phenomena. Surely a force by any other name is no more and no less potent. Both Verworn and Moore feel the need, as we all do, of some term, or terms, by which to explain that activity in matter which we call vital. Other writers have referred to “a peculiar power of synthesis” in plants and animals, which the inanimate forms do not possess.

Ray Lankester, to whom I have already referred in discussing this subject, helps himself out by inventing, not a new force, but a new substance in which he fancies “resides the peculiar property of living matter.” He calls this hypothetical substance “plasmogen,” and thinks of it as an ultimate chemical compound hidden in protoplasm. Has this “ultimate molecule of life” any more scientific or philosophical validity than the old conception of a vital force? It looks very much like another name for the same thing–an attempt to give the mind something to take hold of in dealing with the mystery of living things. This imaginary “life-stuff” of the British scientist is entirely beyond the reach of chemical analysis; no man has ever seen it or proved its existence. In fact it is simply an invention of Ray Lankester to fill a break in the sequence of observed phenomena. Something seems to possess the power of starting or kindling that organizing activity in a living body, and it seems to me it matters little whether we call it “plasmogen,” or a “life principle,” or “biotic energy,” or what not; it surely leavens the loaf. Matter takes on new activities under its influence. Ray Lankester thinks that plasmogen came into being in early geologic ages, and that the conditions which led to its formation have probably never recurred. Whether he thinks its formation was merely a chance hit or not, he does not say.

We see matter all about us, acted upon by the mechanico-chemical forces, that never takes on any of the distinctive phenomena of living bodies. Yet Verworn is convinced that if we could bring the elements of a living body together as Nature does, in the same order and proportion, and combine them in the selfsame way, or bring about the vital conditions, a living being would result. Undoubtedly. It amounts to saying that if we had Nature’s power we could do what she does. If we could marry the elements as she does, and bless the banns as she seems to, we could build a man out of a clay-bank. But clearly physics and chemistry alone, as we know and practice them, are not equal to the task.

III

One of the fundamental characteristics of life is power of adaptation; it will adapt itself to almost any condition; it is willing and accommodating. It is like a stream that can be turned into various channels; the gall insects turn it into channels to suit their ends when they sting the leaf of a tree or the stalk of a plant, and deposit an egg in the wound. “Build me a home and a nursery for my young,” says the insect. “With all my heart,” says the leaf, and forthwith forgets its function as a leaf, and proceeds to build up a structure, often of great delicacy and complexity, to house and cradle its enemy. The current of life flows on blindly and takes any form imposed upon it. But in the case of the vegetable galls it takes life to control life. Man cannot produce these galls by artificial means. But we can take various mechanical and chemical liberties with embryonic animal life in its lower sea-forms. Professor Loeb has fertilized the eggs of sea-urchins by artificial means. The eggs of certain forms may be made to produce twins by altering the constitution of the sea-water, and the twins can be made to grow together so as to produce monstrosities by another chemical change in the sea-water. The eyes of certain fish embryos may be fused into a single cyclopean eye by adding magnesium chloride to the water in which they live. Loeb says, “It is a priori obvious that an unlimited number of pathological variations might be produced by a variation in the concentration and constitution of the sea water, and experience confirms this statement.” It has been found that when frog’s eggs are turned upside down and compressed between two glass plates for a number of hours, some of the eggs give rise to twins. Professor Morgan found that if he destroyed half of a frog’s egg after the first segmentation, the remaining half gave rise to half an embryo, but that if he put the half-egg upside down, and compressed it between two glass plates, he got a perfect embryo frog of half the normal size. Such things show how plastic and adaptive life is. Dr. Carrel’s experiments with living animal tissue immersed in a proper mother-liquid illustrate how the vital process–cell-multiplication–may be induced to go on and on, blindly, aimlessly, for an almost indefinite time. The cells multiply, but they do not organize themselves into a constructive community and build an organ or any purposeful part. They may be likened to a lot of blind masons piling up brick and mortar without any architect to direct their work or furnish them a plan. A living body of the higher type is not merely an association of cells; it is an association and cooeperation of communities of cells, each community working to a definite end and building an harmonious whole. The biochemist who would produce life in the laboratory has before him the problem of compounding matter charged with this organizing tendency or power, and doubtless if he ever should evoke this mysterious process through his chemical reactions, it would possess this power, as this is what distinguishes the organic from the inorganic.