ARTIFICIAL v. NATURAL SELECTION 279 



after a time finds that, within the limited 

 period of his endeavour, he can go no further. 

 But Natural Selection does not operate in this 

 way upon single qualities. Every quality of direct 

 or indirect value to the organism and at the same 

 time the inter-relationships of all qualities, are 

 selected simultaneously. Artificial selection does 

 not give us a true picture of the method of nature. 



Darwin, as I have said, held that the steps 

 of evolution were built out of small individual 

 differences. He did not doubt that these could 

 be accumulated by selection, but he was prepared 

 to believe that there would be halts. I have 

 always foreseen that the Mutationist would finally 

 'hedge' by claiming as mutations the minute 

 differences on which Darwin relied. 1 This 

 tendency is very clearly seen in Mr. Punnett's 

 little book 2 : 



' Doubtless some of the so-called fluctuations are in reality 

 small mutations, whilst others are due to environmental 

 influence ' (p. 72). 



'A cursory examination of horticultural literature must 

 convince anyone, that it is by selection of mutations, often 

 very small, that the gardener improves his varieties. 

 Evolution takes place through the action of selection on 

 these mutations ' (p. 74). 



As the Mutationist comes to study the details 

 of adaptation, and as further fossil records pre- 

 served under peculiarly favourable conditions are 







1 Essays on Evolution, xxxviii, xxxix. 



2 Mendelism. 



