2IO BRAINS OF RATS AND MEN 



change to the frontal areas on the basis of experiments 

 already summarized (pp. 185, 189). But since the 

 available evidence for cortical participation in learned 

 reactions is clearer and more detailed for the occipital 

 cortex than for the frontal cortex, it does not seem 

 necessary to review the latter in this connection. 



Still another aspect of cortical function has been 

 much exploited by the physiologists, namely, its in- 

 hibitory action. There is evidence, both in lower and 

 higher mammals, of inhibitory action of some sort, 

 but the experiments here under consideration shed 

 little light upon this aspect of the question, for they 

 are ill adapted to separate it from other factors. 



The cerebral hemispheres do exert some sort of in- 

 hibitory influence, even as far down the scale as the 

 frog. Decerebrate frogs show stupor and lack of 

 "spontaneity," and this is sometimes ascribed to exci- 

 tation by the operation of specific cerebral inhibitory 

 fibers — a very lame explanation, as Pike (1909, 191 2) 

 has pointed out. Burnett (191 2) has published some 

 experiments which are interesting in this connection. 

 He found that under natural conditions normal frogs 

 catch more flies than decerebrate frogs; but if a nor- 

 mal and a decerebrate specimen are confined together 

 in a glass dish and flies are introduced the flies are 

 generally caught by the decerebrate frog. The expla- 

 nation is that the normal frog is distracted by the un- 

 familiar surroundings and devotes his entire energy 

 to escaping from confinement. The decerebrate frog. 



