142 Studies in Animal Behavior 



fully adaptive for the neurones in the changing in- 

 timacy of whose synapses learning consists, than 

 for the animal as a whole. It is adaptive for the 

 animal as a whole only in so far as his organiza- 

 tion makes the neurones concerned in the learning 

 welcome states of affairs that are favorable to his 

 life and that of his species and reject those that 

 are harmful. 



"Second: A mechanism in the neurones gives 

 results in the behavior of the animal as a whole that 

 seem beyond mechanism. By their unmodifiable 

 abandonment of certain specific conditions and re- 

 tention of others, the animal as a whole can modify 

 its behavior. Their one rule of conduct causes in 

 him a countless complexity of habits. The learning 

 of an animal is an instinct of its neurones." 



Of course the assumption that the neurones re- 

 act so as to make themselves more permeable to 

 stimuli that are beneficial, and to make themselves 

 less permeable to stimuli that are injurious has no 

 direct evidence in its support. Its value consists in 

 its serviceableness as an explanation of learning. 

 But notwithstanding the fact that reactions on the 

 part of cells are very frequently teleological the 

 hypothesis is, I believe, not in accord with what is 

 known of the physiology of the nervous system. So 

 far as we know, nervous impulses are the same in 

 character everywhere. We should expect that up 

 to a certain degree of intensity, like functional stim- 

 ulation in general, nervous impulses would enhance 



