1856.] SPECIFIC CENTRES. 83 



whether or no my book may be wretched, you have done your 

 best to make it less wretched. Sometimes I am in very good 

 spirits and sometimes very low about it. My own mind is 

 decided on the question of the origin of species ; but, good 

 heavens, how little that is worth ! . . . 



[With regard to " specific centres," a passage from a letter 

 dated July 25, 1856, from Sir Charles Lyell to Sir J. D. Hooker 

 (' Life,' vol. ii. p. 216) is of interest : 



" I fear much that if Darwin argues that species are 

 phantoms, he will also have to admit that single centres of 

 dispersion are phantoms also, and that would deprive me 

 of much of the value which I ascribe to the present provinces 

 of animals and plants, as illustrating modern and tertiary 

 changes in physical geography." 



He seems to have recognised, however, that the phantom 

 doctrine would soon have to be faced, for he wrote in the 

 same letter : " Whether Darwin persuades you and me to 

 renounce our faith in species (when geological epochs are 

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

 indefinite modifiability doctrine," 



In the autumn my father was still working at geographical 

 distribution, and again sought aid from Sir J. D. Hooker. 



* f In the course of some weeks, you unfortunate wretch, you 

 will have my MS. on one point of Geographical Distribution. 

 I will, however, never ask such a favour again ; but in regard 

 to this one piece of MS., it is of infinite importance to me for 

 you to see it ; for never in my life have I felt such difficulty 

 what to do, and I heartily wish I could slur the whole subject 

 over." 



In a letter to Sir J. D. Hooker (June, 1856), the following 

 characteristic passage occurs, suggested, no doubt, by the 



G 2 



