220 SCIENCE PROGRESS 



and making of his coat, for his hoof was only to run over the 

 prairie, his coat was to fade into it. Thus, if Thayer's doctrine 

 be accepted, it must be taken to give certainly the most subtle 

 and beautiful proof of the theory of natural selection, being 

 that which most clearly shows it at work, matching the creature 

 to its environment. Such matching is surely never so complete, 

 such adaptation is never so delicately poised, as when the 

 creature's visible form actually vanishes into its surroundings. 

 We are always being accused of living in an age of over- 

 specialisation. The accusation may be just but at least the 

 offence has its compensations. Within the last decade two books 

 on science proper have been published which are in themselves 

 perhaps enough to make us impenitently willing to plead 

 guilty. They are Bergson's LEvolution Creatrice and Thayer's 

 Concealing Coloration — the one the work of a French philo- 

 sopher, the other that of an American artist. Both men are 

 specialists. Yet to read the contribution of either to the theme 

 which has drawn both out of the conventional boundaries of 

 their own studies is to feel that the more profound a man's 

 grasp of his special subject the more piercing may be his insight 

 into that of others. Among the many signs that "Science" 

 (in the narrow sense) is to continue to progress, not the least 

 hopeful is that her problems are continuing to attract not 

 only those who have been trained in her service but also minds 

 whose vigour and acuteness have been tested in other fields. 



