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larval life are superseded by those of a later period.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 in 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 
t» 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 in 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 
