xxv] DARWIN 7 



is more fully treated in my " Darwinism," chap, ix, under 

 the heading " Warning Colours among Insects," and it has thus 

 led to the establishment of a general principle which is very 

 widely applicable, and serves to explain a not inconsiderable 

 proportion of the colours and markings in the animal world. 

 It is, of course, only a wider application of the same funda- 

 mental fact by which Bates had already explained the purpose 

 of " mimicry " among insects, and it is a matter of surprise to 

 me that neither Bates himself nor Darwin had seen the prob- 

 ability of the occurrence of inedibility in the larvae as well as 

 in the perfect insects. 



In the year 1870 Mr. A. W. Bennett read a paper before 

 Section D. of the British Association at Liverpool, entitled 

 "The Theory of Natural Selection from a Mathematical 

 Point of View," and this paper was printed in full in Nature 

 of November 10, 1870. To this I replied on November 17, 

 and my reply so pleased Mr. Darwin that he at once wrote to 

 me as follows : — 



" Down, November 22. 



" My dear Wallace, 



" I must ease myself by writing a few words to say 

 how much I and all in this house admire your article in 

 Nature. You are certainly an unparalleled master in lucidly 

 stating a case and in arguing. Nothing ever was better 

 done than your argument about the term Origin of Species, 

 and about much being gained if we know nothing about 

 precise cause of each variation." 



At the end of the letter he says something about the 

 progress of his great work, " The Descent of Man." 



"I have finished 1st vol. and am half-way through proofs 

 of 2nd vol. of my confounded book, which half kills me by 

 fatigue, and which I fear will quite kill me in your good 

 estimation. 



" If you have leisure, I should much like a little news of 

 you and your doings and your family, 



" Ever yours very sincerely, 



" Ch. Darwin." 



