SPECULATIVE CAUTION 497 



Happily this resolve was broken by the impulse of 

 Darwin's compulsory publication. 



However, Hooker's long established conviction that species 

 are more variable and less easily denned than most naturalists 

 believed, did not bring him at once into the Transmutationist 

 camp. He accepted the considerable variability of species 

 and their spread by migration each from some one original 

 starting place, a point less difficult perhaps to define than the 

 perplexing modes of migration : he accepted even their relation- 

 ship to allied species, their fossil predecessors in the same area, 

 but to accept so much was not to accept their transmutation 

 from other species. He went to India ' possessed, but not 

 converted ' by Darwin's theories, and was somewhat dis- 

 appointed not to find them cleared up by the discovery of 

 transitional forms in Sikkim, the meeting ground of tropical 

 and arctic flora. The actual process of transition had not been 

 observed ; the partial light thrown on the question in frag- 

 mentary discussions was not enough, and until 1858-9, after 

 the consolidation of Darwin's arguments in the famous Abstract, 

 Hooker, as has been already noticed, worked avowedly on the 

 accepted lines of the fixity of species, for which he had so far 

 found no convincing substitute. 



His critical attitude so long maintained may be regarded 

 less as opposition to the tendencies of Darwin's speculations, 

 than as the caution of a judicial mind, that required wholly 

 convincing proof for itself before accepting the theory 

 and all its consequences, and was equally desirous that the 

 proof be wholly convincing for the credit of the friend who 

 advanced it. Darwin never tires of telling how he values his 

 criticisms. They led not to destruction, but to reconstruction. 

 * You never make an objection without doing much good,' 

 he exclaims (November 18, 1856). After a long talk together, 

 ' fighting a battle with you clears my mind wonderfully ' 

 (October 19, 1856), or, touching Hooker's help over the question 

 of large genera varying largely, already mentioned, 'Again 

 I thank you for your valuable assistance. . . . Adios, you 

 terrible worrier of poor theorists ! ' 



But as long as the full argument of the * Origin ' had not 



