462 THE UNFINISHED BOOK. [1857. 



The 339 species have 51 species presenting one or more 

 varieties. The 323 species have only 37. Proportionately 

 (339 : 323 : : 51 : 48'5) they ought to have had 48 J species 

 presenting vars. So that the case goes as I want it, but not 

 strong enough, without it be general, for me to have much 

 confidence in. I am quite convinced yours is the right way ; 

 I had thought of it, but should never have done it had it not 

 been for my most fortunate conversation with you. 



I am quite shocked to find how easily I am muddled, for 

 I had before thought over the subject much, and concluded 

 my way was fair. It is dreadfully erroneous. 



What a disgraceful blunder you have saved me from. I 

 heartily thank you. 



Ever yours, 



C. Darwin. 



P. S. — It is enough to make me tear up all my MS. and 

 give up in despair. 



It will take me several weeks to go over all my materials. 

 But oh, if you knew how thankful I am to you ! 



C. Darwin to J. D . Hooker. 



Down, Aug. [1857]. 



My dear Hooker, — It is a horrid bore you cannot come 

 soon, and I reproach myself that I did not write sooner. 

 How busy you must be ! with such a heap of botanists at 

 Kew. Only think, I have just had a letter from Henslow, 

 saying he will come here between nth and 15th I Is not 

 that grand ? Many thanks about Fiirnrohr. I must humbly 

 ►supplicate Kippist to search for it : he most kindly got Bo- 

 reau for me. 



I am got extremely interested in tabulating, according to 

 mere size of genera, the species having any varieties marked 

 by Greek letters or otherwise : the result (as far as I have yet 

 gone) seems to me one of the most important arguments I 

 have yet met with, that varieties are only small species — or 



