J 304 NATUEAL SELECTION v. SELF- ADAPTATION 363 



self-adaptation ivories in each case. Now I do not find 

 any suggestion as to this. And yet this is obviously 

 the essential point ; since, unless it can he shown how 

 self-adaptation works — i.e. that it is a vera causa, 

 and not a mere word serving to re-state the facts of 

 adaptive evolution — we have got no further in the 

 way of explanation than the physician who said, 

 that the reason why morphia produces sleep is be- 

 cause it possesses a soporific quality. 



Observe, I purposely abstain from considering 

 your criticism of natural selection, which, although 

 perfectly lucid and possibly justifiable, yet certainly 

 does admit of the answer that incipient variations of 

 a fortuitous kind under nature may often be incon- 

 spicuous (while Wallace shows that in animals they 

 are, as a matter of fact, usually considerable). But 

 we need not go into this. The interesting point to 

 all of us must be the constructive part of your work ; 

 and I have tried to explain my difficulty with regard 

 to it. Why should protoplasm he able to adapt itself 

 into the millions of diverse mechanisms of nature by 

 converse with environment ? The theory of natural 

 selection gives a logically possible, even if it be a 

 biologically inadequate, answer. But I cannot see 

 that the theory of self-adaptation does, unless it can 

 he shown that there is some sufficient reason why, say, 

 a desert-environment should produce self -adaptation 

 in the direction of hairs, a marine one in that of 

 fleshiness, &c. &c. 



I have been very frank, because I know you, and 

 therefore that this is what you would prefer. But I 

 am too ill to make myself clear in a letter. I wish 



