74 LIFE OF 



cumstances, basing his argument upon the analogy of 

 domestic animals and plants, the changes which the 

 embryos of many species undergo, and the difficulty of 

 distinguishing species and varieties. 



But we need not here dwell on the works of these 

 thinkers, important as they are to the general history of 

 evolutionary thought, because Darwin's speculations had 

 taken form long before, and he could be but slightly 

 indebted to them. Far in advance of them he was at 

 work collecting and testing the facts which alone could 

 win general support for his views, and experimenting 

 incessantly with the same object in view. Lyell and 

 Hooker were in his confidence, and in Lyell's letters 

 we meet with references such as the following, dated 

 November 13, 1854: "You probably know about this 

 (the remarkable orchid, Catasetum), which will figure 

 in C. Darwin's book on ' Species,' with many other 

 ' ugly facts,' as Hooker, clinging like me to the ortho- 

 dox faith, calls these and other abnormal vagaries," 

 showing at the same time how completely Darwin was 

 the leader, while his friends, advanced as they were, 

 hung back. Again (Lyell to Hooker, July 25, 1856): 

 " Whether Darwin persuades you and me to renounce 

 our faith in species (when geological epochs are con- 

 sidered) or not, I foresee that many will go over to the 

 indefinite modifiability doctrine." 



Further light is thrown on the progress of ideas on 

 species by Sir Joseph Hooker's admirably written Intro- 

 ductory Essay to the "Flora Novae Zelandice," dated 

 November, 1853, in which he discusses among other 

 questions, "The Limits of Species; their Dispersion and 



