INSTINCT 99 



different behavior of the frog. But with abrupt structural 

 changes such as occur in insects with complete metamor- 

 phosis the changes in instinct at successive periods is equally 

 great and often more striking. 



The transitoriness of many instincts has been illustrated 

 in some of the cases referred to, in which the instincts of 

 larval life are superseded by those of a later period. The 

 same trait is commonly manifested hi the behavior of higher 

 forms. Here the instinct may be fostered and continued 

 by habit, and if it does not become aroused by the appropri- 

 ate objects soon fades away. According to Spaulding, "A 

 chicken that has not heard the call of the mother until 

 eight or ten days old then hears it as if it heard it not. I 

 regret to find that on this point my notes are not so full as 

 I could wish, or as they might have been. There is, however, 

 an account of one chicken that could not be returned to the 

 mother when ten days old. The hen followed it and tried 

 to entice it in every way; still it continually left her and ran 

 to the house or to any person of whom it caught sight. This 

 it persisted hi doing, though beaten back with a small branch 

 dozens of times, and, indeed, cruelly maltreated." If 

 calves are prevented from sucking for some time after 

 birth they frequently although not invariably lose the 

 instinct to suck, and may then be safely returned to the 

 mother. There is obviously an adaptiveness in this transi- 

 toriness of instinct in higher forms. Where the instinct 

 finds no proper object to call it forth it is rather of advantage 

 to the animal to be rid of it; the ground is in a measure 

 cleared for the development of new adaptations. 



Modern literature on animal behavior has much to say 

 regarding the kinship of instinct and reflex action. Both 

 are based on inherited organization; both consist to a con- 

 siderable degree of purposive actions in relation to outer 



