332 THE POPULAR SCIENCE MONTHLY 



Reefs." Every other volume came through the inductive-deductive 

 process, tliat is, through an early assemblage of facts followed by a 

 series of trial hypotheses, each of which was rigidly tested by addi- 

 tional 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 fortli 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 thouglit 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. 



Kow 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 jjlants, animals 

 and mau. 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 be- 

 come 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 re- 

 produce 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 ex- 

 planation 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. 



