70 MAN [CHAP. VIII 



Letter 437 caterpillars alone of the rarer moths or butterflies. What 

 think you? I hear from Professor Canestrini l in Italy that 

 females are born in considerable excess with Bombyx mori^ 

 and in greater excess of late years than formerly ! Quatrefages 

 writes to me that he believes they are equal in France. So 

 that the farther I go the deeper I sink into the mire. With 

 cordial thanks for your most valuable letters. 



We remain here till April ist, and then hurrah for home 

 and quiet work. 



Letter 438 To J. Jenner Weir. 



4, Chester Place, N.W., March 2yth [1868]. 



I hardly know which of your three last letters has 

 interested me most. What splendid work I shall have 

 hereafter in selecting and arranging all your facts. Your last 

 letter is most curious all about the bird-catchers and 

 interested us all. I suppose the male chaffinch in " pegging ): 

 approaches the captive singing-bird, from rivalry or jealousy 

 if I am wrong please tell me ; otherwise I will assume so. 

 Can you form any theory about all the many cases which you 

 have given me, and others which have been published, of when 

 one [of a] pair is killed, another soon appearing ? Your fact 

 about the bullfinches in your garden is most curious on this 

 head. 2 Are there everywhere many unpaired birds ? What 

 can the explanation be ? 



Mr. Gould assures me that all the nightingales which first 

 come over are males, and he believes this is so with other 

 migratory birds. But this does not agree with what the bird- 

 catchers say about the common linnet, which I suppose 

 migrates within the limits of England. 



Many thanks for very curious case of Pavo nigripennis? 

 I am very glad to get additional evidence. I have sent your 

 fact to be inserted, if not too late, in four foreign editions 

 which are now printing. I am delighted to hear that you 



1 See Descent of Man (1901), p. 385. 



3 Mr. Weir stated that at Blackheath he never saw or heard a wild 

 bullfinch, yet when one of his caged males died, a wild one in the course 

 of a few days generally came and perched near the widowed female, whose 

 call-note is not loud. Descent of Man (1901), p. 623. 



3 See Animals and Plants, Ed. II., vol. I., p. 306, 



