192 MAN, THE ANIMAL 



wider range of choice exhibit more variety in their 

 mental reactions. But all are similar in that they 

 have repeatedly gone through one set of reactions 

 which proved to be helpful to them. Those 

 reactions that were not useful were not repeated 

 and so did not become fixed nor perfected. Na- 

 ture rewarded the animal that made one set of re- 

 sponses and punished this same animal when It 

 made another. Darwin termed this method the 

 Struggle for Existence. By this method animals 

 learned or acquired definite mental habits and 

 Instincts. 



It seems safe to assume that trial and error 

 played a large part in fixing these habits before 

 they became perfect responses. Such a series of 

 reactions would follow from the variety of stimuli 

 that would impinge on the experimenting organ- 

 ism. Gradually one set of sensory Impulses 

 would dominate in the several possible reflexes 

 thus resulting in a specific reaction. Such a reac- 

 tion, even the very simplest, would have asso- 

 ciated with It numerous other Incomplete reactions 

 that would contribute to Its modification, — all of 

 which would be integrated Into one. 



There is no experimental evidence that reac- 

 tions become established except through long 

 usage which means that they were repeated many 

 times. It is conceivable that such repetitions 

 gradually influenced successive synapses with each 



