248 APPENDIX A 



less. The following references to the subject 

 are to be found in his correspondence with 

 Sir Joseph Hooker in 1854 and 1856, years 

 before the publication of the Origin : — 



1854, July 2. — 'I am glad to hear what you say about 

 parallelism: I am an utter disbeliever of any parallelism 

 more than mere accident.' ^ 



1856, July 13. — 'You say most truly about multiple 

 creations and my notions. If any one case could be proved, 

 I should be smashed ; but as I am writing my book, I try 

 to take as much pains as possible to give the strongest cases 

 opposed to me, and often such conjectures as occur to me." 



1856, July 19. — ' ... it is absolutely necessary that I 

 should discuss single and double creations, as a very crucial 

 point on the general origin of species, and I must confess, 

 with the aid of all sorts of visionary hypotheses, a very 

 hostile one.' ' 



The above-quoted sentences sum up very 

 briefly Darwin's conclusion that evolution as he 

 conceived of it implied that each species had 

 appeared once only in a single continuous area 

 and had then tended to spread from this as from 

 a centre— impUed in fact the soundness of the 

 belief in what were then called 'single centres 

 of creation'. His arguments in favour of this 

 conviction are given in great detail in the first 

 edition of the Origin: first in chapter X, sup- 

 porting the conclusion, — 'it is incredible that 

 individuals identically the same should ever have 

 been produced through natural selection from 



' More Letters, i. 77. _ ^ More Letters, i. 95. 



' More Letters, ii. 249. 



