Alfred Russel Wallace 



summer I hope that Mrs. Wallace and yourself will pay us a 

 visit at Down, soon after you return to London ; for I am 

 sure you will allow me the freedom of an invalid. 



My paper to-morrow at the Linnean Society is simply 

 to prove, alas ! that primrose and cowslip are as good 

 species a« any in the w^orld, and that there is no trust- 

 worthy evidence of one producing the other. The only 

 interesting point is the frequency of the production of 

 natural hybrids, i.e. oxlips, and the existence of one kind 

 of oxlip which constitutes a third good and distinct species. 

 I do not suppose that I shall be able to attend the Linnean 

 Society to-morrow. 



I have been working hard in collecting facts on sexual 

 selection every morning in London, and have done a good 

 deal ; but the subject grows more and more complex, and 

 in many respects more difficult and doubtful. I have had 

 grand success this morning in tracing gradational steps by 

 which the peacock tail has been developed : I quite feel as 

 if I had seen a long line of its progenitors. 



I do not feel that I shall grapple with the sterility argu- 

 ment till my return home; I have tried once or twice and 

 it has made my stomach feel as if it had been placed in a 

 vice. Your paper has driven three of my children half- 

 mad — one sat up to twelve o'clock over it. My second 

 eon, the mathematician, thinks that you have omitted one 

 almost inevitable deduction which apparently would modify 

 the result. He has written out what he thinks, but I have 

 not tried fully to understand him. I suppose that you 

 do not care enough about the subject to like to see what 

 he has written ? 



I hope your book progresses. 



I am intensely anxious to see your paper in Murray's 

 Journal. — My dear Wallace, yours very sincerely, 



Ch. Darwin. 

 202 



