438 GENERAL PRINCIPLES 



forms it is vastly more so. This organ enables the individual 

 animal to profit by experience. A sensation or an experience 

 of any kind to which the organism has once been subjected is in 

 some way registered in the brain (memory) and through it the 

 future responses are modified. The constant stream of highly 

 complex stimuli which pour in upon the organsim from the en- 

 vironment are sifted and analyzed in some way by the brain, 

 and the appropriate responses determined (reason, judgment), 

 and the proper motor stimuli sent out to the organs of response 

 (will) . Animals guided by instinct inherit a few sets of more or 

 less complex responses, which are set in motion by corresponding 

 sets of stimuli, and these responses are little if at all modified. 

 Responses prompted by intelligence are more variable as de- 

 termined by variable external conditions, and the individual 

 exercises an adaptive control. The brain might be called an 

 organ of adaptation, for the degree in which the individual can 

 adapt itself to its environment is a measure of its intelligence. 



