References 237 



sight. A certain familiarity with the habits of street 

 curs will convince one, I think, that the element 

 of behavior, as in some of the cases previously de- 

 scribed, plays a certain role also. 



The recognition of sex has been little analyzed 

 in the mammals. The problem is more complex than 

 in lower forms owing to the higher development of 

 the mammalian mind, and the fact that several dif- 

 ferent senses are usually involved. 



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Craig, W. The expression of emotion in the 

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