Science and Morals and Other Essays, Sir Windle Bertram Coghill Alan [reading books for 7 year olds .TXT] 📗

that an artificial stimulus can in certain cases set up segmentation, but never can it cause the fertilisation of the ovum. It may very likely produce the same change in the membrane that is caused by the entrance of the spermatozoon under normal circumstances—membrane formation may be necessarily coincident with the liberation in the egg of some zymose which arises from a pre-existent zymogen. But we are still some way off any assurance that the main object of the spermatozoon in inducing the development of the egg is this surface alteration. It may be the initial effect; very probably it is; but since the main function of the spermatozoon must be the introduction of germplasm from the male parent, it is too much for anyone to ask us to believe that its main function is concerned with surface alteration.

Loeb argues that the change in the surface membrane is of a chemical character, and that no doubt may be correct; but even if we allow him every scientific fact, or surmise, he is still, as in the other cases with which we have dealt, miles away from any real explanation. He is still inside his chemico-physical explanation to begin with; and, even within that, he still leaves us anxious for the explanation of a number of points—for example, as to the nature of the chemical process which accompanies, or is the cause of, segmentation. We in no way press these questions; for similar demands could be made in so many cases; we only indicate that they are there. What we do press is this—that when an authority comes forward to assure us that all the processes of life, including man's highest as well as his lowest attributes, can be explained on chemico-physical lines, we are entitled to ask for a more cogent proof of it than the demonstration, however complete, of the germination of an egg, caused by artificial stimulus and not by the ordinary method of syngamy, even though that germination may lead to the production of a perfect adult form. We are entitled to ask him to make clear to us not only what is happening within his system, but—which is far more important—what that system is, and how it came into existence. We are entitled to ask why the artificial stimulus, or the entry of the spermatozoon, produces the effects which it is claimed to produce instead of any one of some score of other effects which it might conceivably have produced. Above all we are entitled to ask why there are any effects, or even why there is any ovum or any spermatozoon or curious physiological investigator, to give the artificial stimulus. Until some light is thrown upon these things we are still within the system, or merely hovering round its confines, and are far away from any final or philosophical explanation such as would satisfy the mind of the man who wants to get a real and not a partial knowledge of the things around him.

We may now turn to the question of Vitalism. It was long the regnant theory; then temporarily the Cinderella of biology; it is now returning to its early position, though still denied by those of the older school of thought who cannot imagine the kitchen wench of yesterday the ruler of to-day. One of the objections to Vitalism is that this explanation of living things is thought by ignorant writers to be so inextricably mixed up with theological considerations as to furnish a case of stantis aut cadentis ecclesiae. That is, of course, absurd; but it creates an undoubted bias against the theory. Hence it is the fashion amongst its opponents to write of it as "mystical" or, as Loeb does, as "supernatural," probably the most illogical term that could possibly be used. What is Vitalism? It is the theory that there is some other element—call it entelechy with Driesch, or call it what you like—in living things than those elements known to chemistry and physics. If it is not there, cadit quaestio; if it is there it is not "supernatural." It might with reason be called "super-mechanical," or "super-chemical," or "super-physical"; but if it is in Nature, as it is held to be, it is not "supernatural" in any true sense of that word—no dictionary confines the term "Nature" to the operations of chemistry and physics.

A good deal of the misconception existing on this point comes from pure ignorance of philosophy, a subject with which writers of this school seldom have even a nodding acquaintance. "The idea of a quasi-superhuman intelligence presiding over the forces of the living is met with in the field of regeneration." Echoes of the Cartesian idea of the soul seem to ring in this statement; but it could not have been written by anyone who had mastered the Aristotelian or the Scholastic explanation of matter and form. But let us take this question of Regeneration; the power which all living things have, in some measure, though in very different measure, of reconstructing themselves when injured. It has been dealt with in a masterly manner by Driesch; and we may at once say that we do not think that Loeb has in any way contraverted his argument, nor even entered the first line of defence of that which is built up around what he calls by the somewhat forbidding name of "Harmonious-Equipotential System."

Let us take one particular example, a very remarkable one, which has been cited by both writers—Wolff's experiment on the lens of the eye. The lens is just behind the pupil or central aperture in the iris or coloured ring at the front of the eye, and behind the cornea which is to the eye what a watch-glass is to a watch. If the lens of the eye be removed from a newt, as it is from human beings in the operation for cataract, the animal will grow another one. How does it do it? In certain cases a tiny fragment of the lens has been left behind after the operation, and the new one grows from that. This is sufficiently wonderful, but by no means so wonderful as what happens in other cases in which the entire lens has been removed and the new lens grows from the outer pigmented layer of the margin of the iris. To the unbiological reader one source of origin will not seem more wonderful than the other, but there is really a vast distinction between them. At an early stage in the development of the embryo, the cells composing it become divisible into three layers. It is even possible, as Loeb maintains, that this differentiation is present in the unsegmented ovum, in which case the facts to be detailed become still more remarkable and significant. These layers are known as epi-, meso-, and hypo-blast; and from each one of them arise certain portions of the body, and certain portions only. It would be as remarkable to a biologist to find these layers not breeding true as it would to a fowl-fancier to discover that the eggs of his Buff Orpingtons were producing young turkeys or ducks. Now the lens is an epiblastic structure, and the iris is mesoblastic. Hence the wonder with which we are filled when we find the iris growing a lens. Loeb attempts to explain this in the first instance by telling us that the cells of the iris cannot grow and develop as long as they are pigmented; that the operation wounds the iris, allows pigment to escape, and thus permits of proliferation. We may accept this, and yet ask why it takes on a form of growth familiar to us only in connection with epiblast? The reply is: "Young cells when put into the optic cup always become transparent, no matter what their origin; it looks as if this were due to a chemical influence, exercised by the optic cup or by the liquid it contains.

"Lewis has shown that when the optic cup is transplanted into any other place under the epithelium of a larva of a frog the epithelium will always grow into the cup where the latter comes in contact with the epithelium; and that the ingrowing part will always become transparent." A most remarkable and interesting experiment; it has this very important limitation—that it is always epithelium with which it has to do, whereas in Wolff's experiment the regeneration takes place from mesoblastic tissue. The cause of the transparency may be a chemical reaction—it depends a good deal upon our definition of that phrase. Is protoplasm a chemical compound? Some have considered it so, and spoken of its marvellously complicated molecule. Of course it is made up of carbon, hydrogen, and other substances within the domain of chemistry. But is it, therefore, merely a chemical compound? The reply involves the whole riddle of Vitalism. The author would say that it, as well as all the living things to which it belongs, is purely and solely a chemical compound; and he must take the consequences of his belief. One of these consequences, from which doubtless he would not shrink, would be that a super-chemist (so to speak) could write him and his experiments and his book down in a series of chemical formulæ—a consequence which takes a good deal of believing. But it also involves him in a belief in the rigidity of chemical reactions; and we are entitled to ask for an explanation of the identical behaviour of the chemical reaction in connection with epiblastic and mesoblastic cells—both pure chemical compounds ex hypothesi and, as far as we can tell from their normal behaviour, widely differing from one another. The optic cup, or its contained fluid, is one chemical compound; epithelium is another; mesoblast is a third. We want an explanation of the identical behaviour of the first with either of the two latter; and this should be borne in mind—that the reaction is not a mere matter of "clearing" of a tissue as the histologist would clear his section by oil-of-cloves or other reagent, but of the construction of a different type of cell—epithelial, not connective tissue.

It certainly follows that there must be some superior, at least widely different, agency at work than one of a purely chemical character—something which transcends chemical operations. This is precisely what the Vitalist claims. No one will fail to award praise to any attempts to explain the phenomena of Nature, whether within or without any system. Loeb's book sets out to do a great deal more—to explain what it does not explain—the Organism as a Whole, and thus to give a philosophical explanation of man. It even claims to afford hints for a rule for his life, at least so we gather from the Preface, where, alluding to "that group of freethinkers, including d'Alembert, Diderot, Holbach and Voltaire," the author tells us that they "first dared to follow the consequences of a mechanistic science—incomplete as it then was—to the rules of human conduct, and thereby laid the foundation of that spirit of tolerance, justice, and gentleness which was the hope of our civilisation until it was buried under the wave of homicidal emotion which has swept through the world." On which it is surely reasonable to ask how a chemical reaction can learn so to alter itself as to exhibit "tolerance, justice, and gentleness," attributes which it had not previously possessed? Such claims of this and other writers, who would find in the laws of Nature as formulated to-day (forgetful that their formulæ may to-morrow be cast into the furnace) a rule of life as well as a full explanation of the cosmos, resemble in their lack of base an inverted pyramid.

IV. SCIENCE IN "BONDAGE"

Amongst the numerous taunts which are cast at the Catholic Church there is