DARWIN AND WALLACE 115 



Only four days after the publication of the famous 

 paper, and one day after he had received and read it, 

 Newton began to apply the principles of the theory of 

 Darwin and Wallace to particular cases within his own 

 knowledge. 



I have been very much pleased with a paper in the 

 last number of the Linnean Society's Proc. on " the 

 tendency of Species to form Varieties and on the Per- 

 petuation of Varieties and Species by Natural means of 

 selection," by Darwin and Wallace. I am not quite 

 sure that I altogether agree with them, but there is very 

 much in it that is very good, and most of the ideas pro- 

 pounded are original. I think there is a hint in it on 

 which you might speak, on the subject I suggested to 

 you when at Castle Eden as being a likely one for a 

 paper before the Linnean Society, the variations induced 

 by desert climate, as exemplified in North African Larks 

 and Wheatears. The idea is perhaps not new, i.e. many 

 naturalists know perfectly well that birds from desert 

 localities do not exactly resemble individuals of the same 

 species (i.e. good species, not those of bird-namers) from 

 more favoured districts. Baird of Washington is quite 

 familiar with this fact, and has or is about to put it into 

 print together with the reasons whence he draws his 

 conclusions. The great Gould, too, has made remarks 

 (Proc. Z.S., 1855, p. 78) bearing more or less on the same 

 subject, with respect to the coloration of birds inhabiting 

 forests and plains, sunny and cloudy atmospheres ; but 

 I do not suppose any one has connected these facts with 

 the theory (though it is more than theory) of Darwin and 

 Wallace, nor has any one practically applied their ideas. 

 It seems to me that they can be connected and should 

 be connected thus : any modification of the structure 

 (using the word in its widest sense, even to comprehend 



algebra as 'he tells us a few pages before (vol. i. p. 33) he did from geometry, 

 and as much delight as when the principle of the vernier was explained to 

 him " Extract from " Early Days of Darwinism," MacmiUan's Magazine, 

 February, 1888. 



