256 ANIMAL LIFE 



actions and reactions. Under the head of psychic functions 

 are included all operations of the nervous system as well as 

 all functions of like nature which may exist in organisms 

 without specialized nerve fibers or nerve cells. As thus de- 

 fined mind would include all phenomena of irritability, and 

 even plants have the rudiments of it. The operations of 

 the mind in this sense need not be conscious. With the 

 lower animals almost all of them are automatic and uncon- 

 scious. With man most of them must be so. All func- 

 tions of the sensorium, irritability ^reflex action, instinct, 

 reason, volition, are alike in essential nature though differ- 

 ing greatly in their degree of specialization. 



In another sense the term mind is applied only to con- 

 scious reasoning or conscious volition. In this sense it is 

 mainly an attribute of man, the lower animals showing it 

 in but slight degree. The discussion as to whether lower 

 animals have minds turns on the definition of mind, and 

 our answer to it depends on the definition we adopt. 



FIG. 155. A "pointer" dog in the act of "pointing," a specialized instinct. 

 (Permission of G. O. Shields, publisher of Recreation.) 



