232 miscellanea {continued). [ l %77* 



valuable. I never expected to see the coloured marks on 

 caterpillars so well explained ; and the case of the ocelli 

 delights me especially. . . . 



. . . There is one other subject which has always seemed 

 to me more difficult to explain than even the colours of cater- 

 pillars, and that is the colour of birds' eggs, and I wish you 

 would take this up. 



C. Darwin to Melchior Nenmayr* Vienna. 



Down, Beckenham, Kent, March 9, 1877. 



Dear Sir, — From having been obliged to read other books, 

 I finished only yesterday your essay on ' Die Congerien,' &c.f 



I hope that you will allow me to express my gratitude for 

 the pleasure and instruction which I have derived from read- 

 ing it. It seems to me to be an admirable work ; and is by 

 far the best case which I have ever met with, showing the 

 direct influence of the conditions of life on the organization. 



Mr. Hyatt, who has been studying the Hilgendorf case, 

 writes to me with respect to the conclusions at which he has 

 arrived, and these are nearly the same as yours. He insists 

 that closely similar forms may be derived from distinct lines 

 of descent ; and this is what I formerly called analogical 

 variation. There can now be no doubt that species may 

 become greatly modified through the direct action of the 

 environment. I have some excuse for not having formerly 

 insisted more strongly on this head in my ' Origin of Species/ 

 as most of the best facts have been observed since its publi- 

 cation. 



With my renewed thanks for your most interesting essay, 

 and with the highest respect, I remain, dear Sir, 



Yours very faithfully, 



Charles Darwin. 



* Professor of Palaeontology at t ' Die Congerien und Paludinen- 



Vienna. schichten Slavoniens,' 4to, 1875. 



