Reefs." Every other volume came through the inductive-deductive process, that is, through an early assemblage of facts followed by a series of trial hypotheses, each of which was rigidly tested by additional facts. The most central of these trial hypotheses was that of the building up of adaptations through the selection of the single adaptive variation out of the many fortuitous variations, and this Darwin was unable to rigidly test by facts but was obliged to leave for verification or disproof by work after him.
Darwin passed away in the year 1882, at the age of 73. Out of the simple and quiet life at Down he had sent forth the great upheaval and revolution.
IV
There is no denying that there is to-day a wide reaction against the central feature of Darwin's thought and this leads us to consider the merits of this reaction, as will be more clearly and fully set forth in the succeeding lectures of this series.
Now on this centenary when we are honoring Darwin, many may ask, exactly what is Darwinism? Failure to know leads some to doubt, others to predict a decline, especially where "the wish is father to the thought." Nothing could be less true than to say that there is the least abatement in the force of the main teaching of this great leader, namely, of the evolutionary law of the universe. The vitality of this idea is shown by its invasion of the physical world. Again, Darwinism is the sum of Darwin's observations on earth structure, on plants, animals and man. This vast body of truth and of interpretation still so far surpasses that brought forward by any other observer of nature, and these facts and interpretations are so far confirmed that they have become the very foundation stones of modern biology and geology. Finally, looking at Darwinism as the sum of his generalizations as to the processes of evolution we again find a vast body of well established laws which are also daily becoming more evident. As to the laws of evolution, there is no single biological principle more absolutely proved by the study of living and extinct things since Darwin's time than the broad law of natural selection: certainly the fittest survive and reproduce their kind, the fittest of every degree, classes, orders, genera, species, individuals and even the fittest organs and fittest separate parts of organs. Darwin still gives us the only explanation which has ever been suggested of hundreds of thousands of adaptations of which neither Buffon's view of direct effect of environment nor Lamarck's view of the inheritance of bodily modifications even approach an explanation worthy to be considered. Take the egg of the murre or guillemot, which is so much larger at one end than the other that it can not roll off the cliff on which it is laid, or the seasonal changes of color in the ptarmigan, every one of which is protective.
