Science and Morals and Other Essays

by Sir Bertram Coghill Alan Windle

Some years ago, when I was delivering a lecture at the Cathedral Hall of Westminster, in the course of the questioning which took place at the termination of the discourse, which was on vitalism, I was asked by one who signed his paper, "So and So, Atheist," "What would you say if you saw a duck come out of a hen's egg?" I recognised at once the idea at the back of the question and appreciated the fact that it had been asked by one who, as some one has said, "called himself an advanced free-thinker, but was really a very ignorant and vulgar person who was suffering from a surfeit of the ideas of certain people cleverer than himself." But, as a full discussion of the matter would have taken at least as long as the lecture which I had just concluded, my reply was that before I attempted to explain it I would wait to see the duck come out of the hen's egg, since no man had as yet witnessed such an event. I do not know whether my atheistical questioner was satisfied or not, but I heard no more of him. But, after all, is it not a marvellous thing that a duck never does come out of a hen's egg? If everything happens by chance, as some would have us believe, why is it that a duck does not occasionally emerge from a hen's egg? Surely this is a miraculum, a thing to be wondered at, yet so common that it goes unnoticed, like many other wonderful things which are also matters of common everyday occurrence, such as the spinning of the earth on its own axis and its course round the sun and through the heavens.

If we pursue this question further we shall begin to remember that creatures more nearly related to one another also "breed true." The hen and the duck are both birds, but they are not so nearly allied to one another as the lion and the tiger, both of which are Felidæ, or cats. Yet no one ever expects that a tiger will be born of a lioness, or vice versa. Further, the pug and the greyhound are both of them dogs: the name canis domesticus applies to both, and one would be distinguished from the other in a scientific list as "Var. (i.e. variety) 'pug,'" or "Var. 'greyhound.'" Yet one can imagine the surprise of a breeder if a greyhound was born in his carefully selected and guarded kennel of pugs. In a word, not only species, but varieties do tend to breed true; the child does resemble its parent or parents. No doubt the resemblance is not absolute: there is variation as well as inheritance. Sometimes the variation may be recognised as a feature possessed by a grandparent or even by some collateral relative such as an uncle or great-uncle; sometimes this may not be the case, though the non-recognition of the likeness does not in any way preclude the possibility that the peculiarity may have been also possessed by some other member of the family. But on the whole the offspring does closely resemble its parents; that is to say, not only the species and the variety but the individual "breeds true." "Look like dey are bleedzed to take atter der pa," as Uncle Remus said when he was explaining how the rabbit comes to have a bobtail. Moreover this resemblance is not merely in the great general features. Apart from monstrosities, the children of human beings are human beings; the children of white parents have white skins, those of black progenitors are black. Commonly, though not always by any means, the children of dark-haired parents are themselves dark-haired, and so on. But smaller features are also transmitted, and transmitted too for many generations; for example, the well-known case of the Hapsburg lip, visible in so many portraits of Spanish monarchs and their near relatives, and visible in life to-day. Again, there are families in which the inner part of one eyebrow has the hairs growing upwards instead of in the ordinary way, a feature which is handed on from one generation to another. Even more minute features than this have been known to be transmissible and transmitted, such as a tiny pit in the skin on the ear or on the face. In fact, there is hardly any feature, no matter how small, which may not become a hereditary possession.

If in-and-in breeding occur, as it may do amongst human beings in a locality much removed from other places of habitation, it may even happen that what may be looked upon as a variety of the human race may arise, though when it arises it is always easy to wipe it out and restore things to the normal by the introduction of fresh blood, to use the misleading term commonly employed, where the Biblical word "seed" comes much nearer to the facts.

Thus there is a well-authenticated case in France (in Brittany if I remember right) of a six-fingered race which existed for a number of generations in a very isolated place and was restored to five-fingeredness when an increase in the populousness of the district permitted a wider selection in the matter of marriages.

And similarly, not long ago an account was published of an albino race somewhere in Canada which had acquired a special name.

Perhaps it has been wiped out by this time by wider marriages, though these might be effected with greater difficulty by albinos than by six-fingered persons. At any rate no one can doubt that it might at any time be wiped out by such marriages, though even when apparently wiped out, sporadic cases might be expected to occur: what the breeders call "throws-back," when they see an animal which resembles some ancestor further back in the line of descent than its actual progenitors. Certainly the most remarkable instance of the reliance which we have come to feel respecting this matter of inheritance is that which was afforded by a recent case of disputed paternity interesting on both sides of the Atlantic, since the events in dispute occurred in America and the property and the dispute concerning it were in England.

It was obviously a most difficult and disputable case, but the judge, a shrewd observer, noticed, when the putative father was in the box, a feature in his countenance which seemed closely to resemble what was to be seen in the child which he claimed to be his own. A careful examination of the parents and of the child was made by an eminent sculptor, accustomed to minute observation of small features of variety in those sitting to him as models.

He reported and showed to the court that there were remarkable features in the head of the child which resembled, on the one hand an unusual configuration in the mother—or the woman who claimed to be the mother—and on the other a well-marked feature in her husband. And as a result the father and mother won their case, and were proclaimed the parents of the child because of the resemblance of these features; and, if we think for a moment, we shall see, because also of the reliance which the human race has come to place in the fidelity of inheritance, of its perfect certainty, so to speak, that a duck will not come out of a hen's egg, and the fact of this reliance on a generally received truth remains, whatever may be said as to the legal aspect of such evidence.

Inheritance is a fact recognised by everybody, and the only reason why we refuse to wonder at it is because, like other wonderful yet everyday facts, such as the growth of a great tree from a tiny seed, it is so everyday that we have ceased to wonder at it. It is there: we know that. But have we any kind of idea how it comes about? The duck does not, as a matter of common experience, come out of a hen's egg. Why does it come out of a duck's egg? Why doesn't it come out, if only rarely, from a hen's egg? In other words, do we know what it is that explains inheritance or how it is that there is such a thing as inheritance? Well, candour obliges me to say that we do not. In spite of all the work which has been expended upon this question we are totally ignorant of the mechanism of heredity. Nevertheless it will be instructive to glance at the theories which have been put forward to explain this matter.

All living things spring from a small germ, and in the vast majority of cases this germ is the product in part of the male and in part of the female parent. It is therefore natural that we should in the first place turn our attention to this germ and ask ourselves whether there is anything in its construction which will give us the key of the mystery. There is not, at least there is nothing definite as shown by our most powerful microscopes. To be sure there is a remarkable substance, called chromatin because of its capacity for taking up certain dyes, which evidently plays some profoundly important part in the processes of development. We may suspect that this is the thing which carries the physical characteristics from one generation to another, but we cannot prove it; and though some authorities think that it is, others deny it. Even if it be, it can hardly be supposed that microscopic research will ever be able to establish the fact, and that for reasons which must now be explained.