I] PERIODICITY IN CONVOLUTA 29 



explanations is that they tend to exercise the in- 

 genuity of men of science rather than to advance 

 our knowledge of physiology. To which it may be 

 answered that adaptation is as much a property of 

 protoplasm as weight is a property of matter, and 

 that the biologist is performing a service in showing 

 how deep-bitten into the organism are the adaptations 

 whereby it adjusts itself to its environment. 



The critic replies: That is very true, but to rest 

 content with a teleological explanation, to say that 

 this animal does such and such a thing because 

 it is convenient or useful for it to do that thing- 

 is to renounce profound investigation. Before this 

 can be regarded as the proper philosophical attitude 

 toward life, the resources of chemistry and physics 

 must be exhausted, and the behaviour under con- 

 sideration must at least be proved not to be due to 

 a chemical or physical change induced by some factor 

 or factors of the environment. 



In other words, the least the physiologist can do 

 is to attempt to discover how the adaptive trick is 

 performed by the animal which exhibits it. 



An admirable example of an apparently adaptive 

 character, which is capable of a simple physical 

 explanation, is given by Loeb (1909) in his brilliant 

 essay on the influence of environment on animals. 



The two species of Salamander, Salamandra atra 

 and S. maculosa occupy distinct stations. The former 



