202 CHARLES DARWIN. 



" I enclose a letter from Fritz Miiller which I think is well 

 worth reading, and which please to return to me. 



"You will see he lays much stress on the difficulty of 

 several remotely allied forms all imitating some one species. 

 Mr. Wallace did not think that there was so much weight in 

 this objection as I do. It is, however, possible that a few 

 species in widely different groups, before they had diverged 

 much, should have accidentally resembled, to a certain extent, 

 some one species. You will also see in this letter a strange 

 speculation, which I should not dare to publish, about the 

 appreciation of certain colours being developed in those species 

 which frequently behold other forms similarly ornamented. I 

 do not feel at all sure that this view is as incredible as it may 

 at first appear. Similar ideas have passed through my mind 

 when considering the dull colours of all the organisms which 

 inhabit dull-coloured regions, such as Patagonia and the 

 Galapagos Is. I suppose you know Mr. Eiley's excellent 

 essay on mimicry in the last report on the noxious insects of 

 Missouri or some such title. 



" I hope your work may be in every way successful. 

 " I remain, dear Sir, yours faithfully, 



" CHARLES DARWIN." 



The next letter deals with mimetic resemblance : 



" Mar. 28, 1872. "Down. 



"DEAR SIR I thank you for your information on various 

 subjects. The point to which you allude seems to me very 

 obscure, and I hardly venture to express an opinion on it 

 My first impression is that the colour of an imitating form 

 might be modified to any extent without any tendency being 

 given to the retention of ancient structural peculiarities. The 

 difficulty of the subject seems to me to follow from our 

 complete ignorance of the causes which have led to the generic 

 differences between the imitating and imitated forms. The 

 subject however seems worth investigating. If the imitator 

 habitually lives in company with the imitated, it would be apt 

 to follow in some respects the same habits of life, and this 



