THE ANALYSIS OF BEHAVIOUR 141 



beak is thrust among the grain. Like the frog, it responds to 

 stimuli, and it sees and hears in so far as seeing and hearing are 

 the stimuli to movements; but sight and hearing do not, ap- 

 parently, evoke memories or utilise experience. Its movements 

 are perfectly co-ordinated. There is the same inevitable response 

 to external stimuli, the same automatism of activity, and the 

 same lack of spontaneity and volition (which latter is indicated 

 by spontaneity) that we see in the decerebrate frog. 



Among the mammals the cerebral hemispheres are much more 

 highly developed, again, than in the bird, and their removal is 

 a formidable operation. Yet it has been accomplished in the 

 dog, and when the animal is nursed with the utmost care and 

 solicitude it may survive for over a year. In the few successful 

 experiments that have been made there has been some little 

 difficulty in exactly describing the condition of the patients. 

 As in the frog and bird, there is no paralysis and no lack of 

 co-ordination so long as the cerebellum is intact. All ordinary 

 movements are carried out, and, as in the bird, there is a tendency 

 to restlessness. The sense organs are active in so far as the motor 

 organs can respond to ordinary sensory stimuli, but things that 

 would, in the intact dog, evoke expressions of terror, dislike, 

 and pleasure, do not appear to affect the decerebrate animal in 

 anything like the same degree. Signs of hunger are exhibited, 

 and food brought near to the nose is eaten. Disagreeable food 

 may be rejected (for instance, one of Golz's dogs would not eat 

 the flesh of another dog). Both in decerebrate dogs and cats 

 painful stimulation elicited expressions of anger (growling, 

 barking, and snarling), but no caressing could evoke any indica- 

 tions of pleasure or affection. There was apparently no dream- 

 ing. Finally (a most curious thing), Golz's dog ate much more 

 than the normal animal did. 



Nervous Inhibition. 



We must say more about these results. In the decerebrate 

 mammal there is the same lack of spontaneous activity as in the 

 frog and bird, understanding by this the absence of apparently 

 willed, or deliberated, or intelligent, or chosen activities, and 

 not the aimless, automatic activity to which we referred above 

 as " restlessness." There is the same tendency for a stimulus 

 to evoke an inevitable response the actions of the animal can 

 be predicted. But the inhibitions are still more interesting. 



