194 NATURAL SCIENCE. September. 



best suits, the prevailing conditions. Thus a natural selection comes 

 to pass : the existing species undergo adaptation, change, separation, 

 and perfection. In the course of the countless great cycles of time, 

 which have flown since the appearance of the first elementary pri- 

 mordial form of life, there arose in this manner the whole series of 

 animal and vegetable organisation, of which man regards himself as 

 the crowning-point. Darwin's teaching quickly became common 

 property, and we trace its influence to-day in almost all spheres of 

 mental activity. His opponents, who, the more they were outside 

 the circle of naturalists, fought not so much against Darwin's own 

 idea, the selection theory, as against the old theory of descent, have 

 continually been growing fewer and quieter, in proportion as Dar- 

 winism, from being the standard of a special philosophical idea of 

 life, has become the object of thoughtful scientific research. And the 

 time does not now seem distant when Darwinism will no more be re- 

 garded as a party question than is the Copernican astronomical 

 system. 



We can then, without prejudice, ask ourselves the question, 

 What influence has Darwin's work had on the development of 

 zoology ? 



Firstly, it may be noted that at the time of the propounding of 

 Darwin's theories, the two branches of natural history were in very 

 different positions. While in the botanic system physiology had already 

 gained its rightful place, an exclusively systematic morphological ad- 

 justment was still reigning in zoology. What wonder that a doctrine, 

 whose main idea was to explain the origin of forms, had to bring 

 about a revolution far greater in zoology than in botany ? That 

 Darwin himself was above all a zoologist, his examples and evidence 

 being principally taken from the animal world, and that further, the 

 phenomena of the " struggle for life " and of " natural selection " in the 

 animal kingdom are much more obvious and varied than in the 

 vegetable kingdom — these data must be considered if we want to 

 explain why Darwinism took root so much more quickly and deeply 

 in zoology than in botany. Nevertheless, in both it finally prevailed 

 in the same way, and there can be very few examples in the intellec- 

 tual evolution of mankind that produced such a revolution in the 

 foundations of a science as did the selection theory in the branches 

 mentioned. Description and superficial grouping gave place to the 

 higher problem of the causal foundation of forms ; the plodding industry 

 of the describer had to be united with the method of comparison, the 

 eye of imagination. 



The first and most important task was the transformation of the 

 system based upon Linnaeus and Cuvier into a history of the descent 

 of living forms. E. Haeckel, with his aspiring genius, sought to be fully 

 just to it by sketching the first pedigrees in his ingenious system of 

 the organic sciences — the "General Morphology of the Organism."^ 



1 E. Haeckel, " Generelle Morphologie der Organismen." Berlin, 1866. 



