BIOLOGY 



and so forth, would probably have to receive special 

 treatment if only on account of the vastness of the 

 subject-matter, just as the physiology of plants will 

 probably always be treated as distinct from that 

 of animals. These are matters of convenience 

 rather than of logical arrangement. 



Experimental Psychology, including what is 

 commonly called the Behaviour of Animals, is a 

 branch of Physiology which is at present very 

 much in evidence. It forms one of the chief 

 battle-fields upon which the incessant and weari- 

 some conflicts between the ' mechanists ' and the 

 ' vitalists ' are carried on. As Professor H. S. 

 Jennings says, " The chief interest of the subject 

 of the behaviour of animals undoubtedly lies, for 

 most, in its relation to the development of psychic 

 behaviour, as shown by man. The behaviour of 

 the lowest organisms must form a fundamental 

 part of comparative psychology." Jennings' ad- 

 mirable book on this subject illustrates very well 

 the kind of work that is being done in this field, 

 and his attempt to trace the function of intelligence 

 right down to the unicellular organisms is full of 

 interest. 



As examples of the extreme mechanistic school 

 we may mention the voluminous writings of 

 the distinguished experimentalist Loeb, who, if 

 I understand him rightly, would interpret the 



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