MODERN EVOLUTION. 143 



for the great work he has undertaken and accom- 

 plished." 



In a letter to Wallace dated 2Oth April, 1870, 

 Darwin says, " There has never been passed on me, 

 or, indeed, on any one, a higher eulogium than yours. 

 I wish that I fully deserved it. Your modesty and 

 candour are very far from new to me. I hope it is 

 a satisfaction to you to reflect and very few things 

 in my life have been more satisfactory to me that 

 we have never felt any jealousy towards each other, 

 though in one sense rivals. I believe I can say this 

 of myself with truth, and I am absolutely sure it is 

 true of you." 



But on one question, and that round which dis- 

 cussion still rages, the friends were poles asunder. 

 There had been correspondence between them as 

 to the bearing of the theory of natural selection on 

 man, and in April, 1869, Darwin wrote, " As you 

 expected, I differ grievously from you, and I am 

 very sorry for it. I can see no necessity for calling 

 in an additional and proximate cause in regard to 

 man." In the fifteenth chapter of his comprehensive 

 book on Darwinism, Wallace admits the action of 

 natural selection in man's physical structure. This 

 structure classes him among the vertebrates; the 

 mode of human suckling classes him among the 

 mammals; his blood, his muscles, and his nerves, 

 the structure of his heart with its veins and arteries, 

 his lungs and his whole respiratory and circulatory 



