THE BRAIN 125 



latter statement is not to be challenged; it is safer than 

 the former which really rests on our imagining ourselves 

 in the place of the cat. 



We feel very skeptical regarding the possibility of 

 disciplining an ant so that it will not approach a lump 

 of sugar. The fact that a cat can be trained as de- 

 scribed while an ant probably cannot, shows just what 

 is meant by the "high" as contrasted with the "low" 

 type of nervous system. Wonderful as the com- 

 munity life of ants and bees appears to us, it is an 

 inflexible life in which there is but slight differentiation 

 of individuals. An ant which has passed through the 

 several stages of development enters into the life of the 

 colony with a certain standard equipment for the part 

 it is to play. It probably adds scarcely anything to 

 this initial equipment as a result of its contacts, failures, 

 and successes. It does not come to have any individu- 

 ality that the human observer can discover. Dogs 

 and cats, on the contrary, have plastic nervous systems 

 which are affected by countless impressions and endow 

 these animals with well-marked personalities. 



To remove the cerebrum is to rob an animal of what 

 it has acquired in living its own life. What remains 

 is the common heritage of the race. This is borne out 

 by the classic experiments upon the pigeon. Early in 

 the last century the condition of this bird after decere- 

 bration was carefully described. Many repetitions of 

 the operation have modified the original conclusions in 

 some details but have not shaken their principal lessons. 

 The decerebrate pigeon retains striking reflex capacities 

 but can hardly be thought of as a sentient or teachable 

 being. 



The bird is most of the time in an inert state suggestive 

 of dozing. It can be roused by positive stimulation 

 and reacts well but quickly subsides once more. For 

 example, if it is tossed into the air it will fly for a short 

 distance. The direction of its flight is probably a 

 matter of chance but it will avoid obstacles and may 



