492. THE HISTORY OF BIOLOGY 



the teleological explanation of nature — that is, the same as Kolliker 

 maintained and Huxley denied. To such divergent interpretations could 

 Darwin's theory give rise. 



Darwin had also found a convinced supporter and a lifelong friend in 

 Joseph Dalton Hooker (1817-1911), a keen explorer in various exotic coun- 

 tries, a distinguished plant-systematist, and finally director of Kew Gardens 

 in London. Darwin was engaged in an almost constant interchange of ideas 

 with him during the many years he w^orked at his theory; when eventually 

 The Origin of Species was published. Hooker zealously defended the new the- 

 ory of descent, both in articles in the press and in his own more important 

 works. In particular, the introduction to his book on the flora of Tasmania, 

 which was published in the year after Tbe Origin of Species, represents a defence 

 of these doctrines, based partly on geographical arguments and partly on evi- 

 dence derived from classification, with special reference to the many phaner- 

 ogam genera which are so rich in species and, owing to their numerous 

 middle-forms, are so difficult to classify — Rubus, Rosa, Salix, and others. 

 Darwin's later researches into plant physiology were also supported to the 

 utmost by Hooker; in fact, of all the champions of Darwinism he was, on 

 the whole, in closest personal contact with its founder. 



Development of Danvinism in England and Germany 

 It was from many different quarters, then, that Darwin won support for 

 his theory of descent; in fact, as has often been emphasized before, it be- 

 came the most widely cherished scientific idea of the age. In these circum- 

 stances it was obvious that many forces were destined to make for its further 

 development. Towards this end, however, it was possible to follow differ- 

 ent methods; of these there were really two that immediately came into use 

 — one in each of the two countries that came to be the principal centres of 

 Darwinism; in Germany recourse was had to the method which was only 

 hinted at by Darwin himself, of seeking fresh proofs of the descent theory 

 in comparative morphology and embryology, while in England his support- 

 ers followed the experimental and statistical method, in which Darwin him- 

 self had expressed the greatest confidence. These two courses will be described 

 in the following. In this connexion, however, we must first mention one 

 thinker who, although not a professional biologist, yet sought more con- 

 sistently than most people to apply the descent theory, in the form that 

 Darwin had given it, to all the phenomena of life, and who was regarded 

 by his contemporaries as the philosopher of evolution above all others. 



Herbert Spencer was born at Derby in the midlands, in the year 1810, 

 the son of a schoolmaster. His parents were both Free Church people, but 

 belonged to different sects, and this lack of harmony induced feelings of 

 doubt in the son at an early age; in political radicalism, on the other hand, 

 he was fully in accord with his home throughout his life. He received a good 



