478 ZOOLOGY SINCE DARWIN. 



thoroughly formulated by Lamarck. 1 But the theory of natural selec- 

 tion proposed by the illustrious Briton for the first time attempted to 

 place it on a scientific basis. The manifest phenomena of inheritance 

 and variation are the main supports of his bold doctrine, the axis on 

 which revolves the great loom of life which is propelled by the struggle 

 of all living things to maintain themselves and to bring forth new life. 

 The cause of the countless varieties of suitably modified forms has 

 been made clear by Darwin, for he has shown that both the mainte- 

 nance of the individual and that of the species require a perpetual 

 struggle with the influences of the environment and with competing 

 individuals, a struggle in which that only survives which is best 

 adapted and most suitable to the existing conditions. Therefore there 

 occurs a natural selection, the existing species undergoing an adapta- 

 tion, a transformation, a division, and a completion. In the course of 

 the immeasurably great spaces of time which have elapsed since the 

 appearance of the first elementary living being, there has arisen the 

 entire ascending series of vegetable and animal organisms, at whose 

 head man now regards himself. 



The Darwinian theory has become common property, and we can 

 trace its influence in almost all departments of intellectual activity. 

 Its opponents — who, by the way, outside the circle of naturalists, did 

 not combat in Darwin so much his own work, the theory of selection, 

 as the older theory of descent — have become ever fewer and more quiet 

 as the doctrine has ceased to be put forward as a definite philosophical 

 theory of life and has become the object of special scientific investiga- 

 tion. And the time appears to be not far distant when the Darwinian 

 theory will be no more considered as a matter for controversy than is 

 the Copernican theory of the solar system. 



We can, therefore, dispassionately turn to the question, " What 

 influence has Darwin's work had upon the development of zoology?" 



First, it should be pointed out that the Darwinian theory encountered 

 the two great branches of natural history under very different con- 

 ditions. While in the science of botany, physiology had already 

 obtained its proper place, there still prevailed in zoology a tendency 

 to exclusive systematic morphology. What wonder that a doctrine 

 whose highest aim consisted in the elucidation of forms should effect a 

 much more powerful evolution in zoology than in botany ! That Dar- 

 win himself was specially trained as a zoologist and hence took most 

 of his examples from the animal kingdom, and that, besides, the phe- 

 nomena of the " struggle for existence," as well as those of " natural 

 selection," are much more striking and manifold in that domain than 

 in the vegetable kingdom, should be considered as secondary causes in 

 explaining why the Darwinian theory took so much quicker and deeper 

 root in zoology than in botany. 



•J. Lamarck, Philosophie zoologique, Paris, 1809. Translated into German by A. 

 Lang under the title: " Zoologische Philosophie von Jean Lamarck, nehst einer 

 biographiachen Einleitung von Charles Martins." Jena, 1876. 



