happen to be born somewhat resembling the bark of the tree in appearance, it would have a chance of escaping unobserved the birds that snap up its brighter-colored kindred. Of the progeny of this one, such as inherited this peculiarity would have the same chance of preserving life; and so, in the long course of time, would grow of a species so closely resembling the bark of the tree on which it lived, as to find its safety therein. In the same way, if any individual should happen to be born with increased facility for securing subsistence, either greater efficiency in obtaining food, or greater capacity for assimilating the food at hand, such individual would have increased chance of surviving in the struggle for life; and its progeny inheriting the same peculiarity would, by having the same chance of surviving, increase the tendency to propagate this peculiarity of structure. The great changes which the earth's surface has undergone would give greater room for the display of this struggle for life. Change of climate and soil would change vegetation. And this change of the conditions. of life would impose new conditions upon the chances of survivorship. It might intensify the chances of the predominating varieties, or it might nullify their chances and give increased chances to some new peculiarity. Besides the law of survivorship of the fittest, which is called the law of Natural Selection, there is another element, somewhat analogous, called Sexual Selection. The males of certain animals have a contest for the possession of the female. She remains an indifferent spectator, and quietly goes off with the victor. Here the strongest and most agile males have progeny, while the weaker leave no offspring. Hence there is a tendency to produce a race of strong active males. In other races, particularly among birds, the female makes her selection. One species is carried away by song. The males exercise all their vocal powers, and the sweetest singer carries away the prize. Another species is attracted by brilliant plumage; and here the lucky male endowed with the brightest feathers succeeds. This course of selection tends in the long lapse of ages to increase the musical power in the one species, and the brilliancy of plumage in the other. However minute any single variation from existing types might be, it is said that give time enough, time without stint, time without limit, these processes of natural selection, together with the changes of climate and surface, would be sufficient to account for the production of the various diversified forms of life which have appeared since the first were brought into being. But not only might new forms of life be so produced. It is further said, there are reasons for believing they have been actually so produced. The fact that new breeds, that new temporary varieties are produced in a short time by superintending human care, raises the presumption that permanent changes of structure, that is, new species, would be produced by natural causes, operating for an indefinite duration in a way analogous to human care. For in Some facts strengthen this presumption. stance: pigs in Florida feed on an herb which rots off the hoofs of all but black pigs. This cause has not been operating long enough to prevent the birth of light or party-colored pigs; but it prevents any but the black from arriving at maturity. Further it is said, that parts that are serviceable in the lower orders of animals are found in a rudimentary state in the higher, as if they had gradually disappeared by disuse. For instance, the os coccyx in man is a rudimentary tail. And the puncture in the lower part of the os humerus, which is the passage for a nerve in monkeys, is of no use in the human frame. Yet it is found in one per cent. of human skeletons of the present day, and in a larger per cent. of human skeletons three or four thousand years old, in some parts of France. So far I have offered, not a sketch, but only a rude indication of the general drift of the theory of specific creation and of Darwin's theory of the laws of selection. As to the respective merits and probabilities of these theories, I do not pretend to offer an opinion. Non nostrum inter vos tantas componere lites. Men who devote their lives to scientific investigations will toil to a determination, and the world will accept the result. But there are some suggestions that any of us may make about Darwin's theory. He does not pretend to solve the question, as to the origin of life, or the essence of life, or the power that produces the initial variations in the forms of life which give opportunity for selection. Accepting these, his aim is to ascertain and determine a law by which they produce the permanent forms of life, which we call species. His theory as to the existence of this law, is gaining ground daily among men devoted to natural science. But his theory can hardly yet be called "the law" of the development of species. For a true law of nature. explaining the phenomena of a certain class, must ex plain all the phenomena of that class. It can not be accepted as a law of nature, if it be inconsistent with a single fact of nature. And the law of selection confessedly does not explain all the phenomena of the development of species. For Darwin says, there are in man, and other animals, parts which do not appear to be of any present use, or to have ever been of use in any previous form of life. And such parts can not be accounted for by the law of selection. Further, even so far as the law of selection is consistent with known facts, it can not now be taken as absolutely true, but only as provisionally true. For a larger acquaintance with the facts of nature may show it to be incorrect, and require it to be modified and abandoned. The Ptolemaic theory of the universe was a good scientific theory in its day, for it was consistent with all the facts then known of the heavenly bodies. But a larger acquaintance with the movements of those bodies required that theory to be dropped and supplanted by the Copernican theory. Finally, although several species have disappeared within the last two thousand years, it is not known that a single new species has appeared since the last fossil era. It must therefore take, so far as we know, thousands of years, to produce any, even the smallest, permanent change in the structure of either animal or vegetable life. But though we thus know that a very long period is necessary, we do not know how much would be sufficient. We have not yet, therefore, attained at anything like a unit of measurement of time required for the workings of Darwin's law. But late discoveries have shown that the people who lived in southern France when the reindeer and the hairy elephant abounded there, attained not only mechanical skill, but considerable artistic power in carving. The skeletons found in the cave of Engis show that man, just as we see him now, with well-developed skull of the present type, existed in the post-pliocene periods. Indications of man, flint implements made by him, have indeed been found dating back to the still earlier period when the tropical elephant roamed in France. Lyell, speaking of changes in physical geography since those skeletons were washed into the cave of Engis, says, although we may be unable to estimate the minimum required for the changes in physical geography above alluded to, we can not fail to perceive that the duration. of the period (the post-pliocene) must have been very protracted, and that other ages of comparative inaction may have followed, separating the post-pliocene from the historical periods, and constituting an interval no less indefinite in its duration." "But Then if man, the final product, existed fully developed, as we see him now, so early, and we are still unable to estimate the duration required by Darwin's law, to produce even the slightest change of species, it may be that the development from a mollusk up to man, in accordance with Darwin's law, would demand even greater duration than the dizzy cycles allowed by geology for the formation of all the earth's crust. While men of science are interested in investigating and ferreting out the truths of nature, the world at large are more concerned in the consequences of the researches than in the researches themselves. More people care for an accurate prediction of the weather, |