THE THEORY OF ORGANIC EVOLUTION 171 



so far as to believe there is small chance of it ever being 

 proved. 15 



Even if the Lamarckian hypothesis should be substan- 

 tiated by satisfactory experimental proof, there still re- 

 main certain features of animal organization which are 

 not readily explicable in terms of this theory. For ex- 

 ample : The resemblance of many animals to their surround- 

 ings is so striking that it is commonly regarded as a means 

 of protection from enemies and hence of life and death import- 

 ance. The importance attached by Darwin to such adaptive 

 features of animal life led to their over-emphasis during the 

 post-Darwinian period. It is undoubtedly true that many of 

 the supposed examples of this form of adaptation are imagin- 

 ary. The reaction against the assumption that almost every 

 structure and every action of a living thing was adaptive 

 went to the opposite extreme, and at the close of the nine- 

 teenth century some biologists seemed to regard the whole 

 phenomenon of adaptation as a myth. When, however, due 

 allowance is made for the over-emphasis of adaptation, 

 when it is frankly acknowledged that animals may have 

 many features which are non-adaptive if not positively 

 harmful, and when we understand that it is the all-round 

 ability to meet the necessities of existence rather than a few 

 particular tests, which constitutes survival value, the fact 

 remains that a certain quality of fitness is one of the most 

 widespread features among living things. We cannot ex- 

 plain this fact by denying its existence. Resemblance to the 

 environment is a fact in many cases. After making every 

 allowance, there remain many instances which can be ex- 

 plained most reasonably on the assumption that resem- 

 blance to the surroundings is an important means of pro- 

 tection. 



16 The recent work of Guyer and Smith, who seem to have induced the 

 inheritance of eye defects in rabbits, is of the greatest interest' but confir- 

 mation and more extended experimentation is needed before the results can 

 be regarded as conclusive. Jour. Exp. Zool., Vol. 31, No. 2, 1920. 



