clue to problems of extraordinary and widely spread interest. On the other hand, the support this theory receives through being able to offer a ready and complete explanation of so many and such divers facts is very great indeed, and becomes all the more significant when we reflect that the facts themselves only came to light, or received serious attention, some time after the promulgation of the theory. The conclusion we have arrived at is, that the colours of animals and plants are no mere accidents, and are not created for our special benefit, but are directly useful to their possessors, and have been acquired because they are useful. Were any additional argument necessary, it would be easy to find it in the fact that men are so far from being in agreement as to what is and what is not beautiful, that the ideal of one nation may be the horror of another; that a picture which an Art Committee may select as beautiful, may appear to the public, for whom it is purchased, as entirely destitute of beauty; that the various devices which savage races practise in order to render themselves, as they consider, beautiful, appear disfigurements to other nations. So then it appears, on the one hand, that not only is there no general agreement among mankind as to what is beautiful, but that different nations, or the same nation at different times, absolutely contradict each other. Some other explanation is necessary of the beautiful colours of animals and plants, and we see what that explanation is in the great law of Utility, expounded by the doctrine of Evolution, for the full enunciation of which we are indebted to Darwin. LECTURE VI OBJECTIONS TO THE DARWINIAN THEORY THE best possible mode of testing a theory is to consider the objections which have been raised against it. It is impossible for us to deal here with all the objections which have been put forward, but I propose to select those which appear the most important-i.e., those which have been urged with the greatest force and persistency by men specially competent to deal with the subject. It is interesting to note that, in spite of the fierce storm of criticism to which the theory has been exposed, and the considerable amount of literature written on the subject-no small number of books having been written for the express purpose of "smashing Darwin "-yet nowhere are the objections and difficulties more clearly stated than by Darwin himself. Very few of any real importance have been added to the list given by Darwin, while he himself has indicated others that had escaped the notice of his opponents. It seems strange to have to claim credit for candour; yet candour so striking as Darwin's does demand special and cordial recognition. Whether he was right or wrong in his conclusions, Darwin simply sought to determine the truth, and was always ready to discuss and consider in detail even the most trivial and thoughtless objections. MISSING LINKS. The most popular objection, and in many ways the most famous, is that of the so-called Missing Links. If the present existing animals are descended from ancestors which were unlike them in former geological times, and if all animals are really akin or cousins, where are the intermediate forms, the missing links? These must on the theory of Evolution have existed. Can we produce them? or if not, can we give any reasonable explanation of our failure? We must at once admit that the demand is absolutely fair, and one which must be met. This question, although dealt with incidentally in former lectures, it is well to reconsider more directly. We have really two distinct problems to deal with, two kinds of links to be sought for-viz., (1) Links between existing animals, which must occur if the animals are akin to one another; (2) Links between existing and extinct animals. Let us consider these separately. Links between the several kinds of existing animals. -Failure to find these has often resulted from misdirected efforts, from looking in the wrong direction. A straight line being the shortest distance between two points, it is commonly and not unnaturally assumed that the link must lie in the line connecting the two forms directly. True links are, however, not directly intermediate, the real relation being that of descent from a common ancestor, or branches of one stem. Take for example the domestic pigeons. The blue rock is the common ancestor of all our domestic races, and is not in any sense intermediate between existing forms, such as a pouter and a fantail. Such intermediate forms have not existed at any time. So it is with ourselves: the real bond of union is through descent; two brothers are related, not directly, but through the parents; and with cousins the grandfather forms the real link. These examples show that the actual links are not direct, but indirect; and that, unless careful, we may spend much time in looking for links where they could not exist, and overlook the real ones which are before our eyes all the time. This may be rendered deceptive by the occurrence of actual intermediate forms which are not true links, and against which we must be on our guard. example will make this point clear. An The horse and the donkey are closely allied animals: midway between them is the mule, which shares the characters of both its parents. Yet this is clearly no true link, but an artificial unnatural creation that could not possibly have existed prior to either the horse or the donkey. HORSE MULE DONKEY 1 ANCESTOR Developmental evidence we have found to be of the utmost value, for the early stages in the development of animals are themselves the very links we want; sometimes distorted or modified, but usually recognisable with sufficient care. Take, for example, the fact of the prawn and the barnacle both commencing life in the same form-i.e., the Nauplius. This is evidence of a most cogent character in support of their descent from a common ancestor, and here the Nauplius is the ancestral form, or link from which both were derived. Rudiments or vestiges also give most valuable evidence. For instance, the short tail of the crab ; the splint bones of the horse's leg; the mute letters in our words: points which were fully considered in a previous lecture.* Links between the Present and the Past. This was Cuvier's difficulty, and formed the basis of an objection which was raised with fatal force. If existing animals are descended from extinct forms or fossils, why do the gaps appear so marked, and where are the intermediate stages which should exist? This question we have already dealt with at length in a former lecture,+ where we saw that the objection could be met in its chief part by the imperfection of the geological record. We saw the extreme improbability that a continuous series of transitional forms could be preserved, owing to the fact that only cer * See page 95. † See page 60. |