i864— 1869] STERILITY OF HYBRIDS 297 



A. R. Wallace to C. Darwin. Letter 214 



Hurstpierpoint, [April?] 8th, 1S68. 



I am sorry you should have given yourself the trouble 

 to answer my ideas on sterility. If you are not convinced, 

 I have little doubt but that I am wrong ; and, in fact, I 

 was only half convinced by my own arguments, and I now 

 think there is about an even chance that Natural Selection 

 may or may not be able to accumulate sterility. If my 

 first proposition is modified to the existence of a species 

 and a variety in the same area, it will do just as well 

 for my argument. Such certainly do exist. They are 

 fertile together, and yet each maintains itself tolerably 

 distinct. I low can this be, if there is no disinclination to 

 crossing ? 



My belief certainly is that number of offspring is not so 

 important an element in keeping up population of a species 

 as supply of food and other favourable conditions ; because 

 the numbers of a species constantly vary greatly in different 

 parts of its own area, whereas the average number of offspring 

 is not a very variable element. 



However, I will say no more, but leave the problem 

 as insoluble, only fearing that it will become a formidable 

 weapon in the hands of the enemies of Natural Selection. 



To J. D. Hooker. Letter 215 



The following extract from a letter to Sir Joseph Hooker (dated 

 April 3rd, 1868) refers to his Presidential Address for the approaching 

 meeting of the British Association at Norwich. 



Some account of Sir Joseph's success is given in the Life and 

 Letters, III., p. too, also in Huxley's Life, Vol. I., p. 297, where Huxley 

 writes to Darwin : — 



" We had a capital meeting at Norwich, and dear old Hooker 

 came out in great force, as he always does in emergencies. The only 

 fault was the terrible ' Darwinismus ' which spread over the section 

 and crept out when you least expected it, even in Fergusson's lecture 

 on ' Buddhist Temples.' You will have the rare happiness to see your 

 ideas triumphant during your lifetime. 



" P.S. — I am going into opposition ; I can't stand it." 



Down, April 3rd [1S68]. 



I have been thinking over your Presidential Address ; 

 I declare I made myself quite uncomfortable by fancying 

 I had to do it, and feeling myself utterly dumbfounded. 



