CEREBRUM 



187 



being in a healthy and well-nourished condition during the 

 training is manifest. 



The power of differentiating various stimuli and their reactions 

 is correlated with the development of the cerebrum and becomes 

 more perfect as the animal scale is ascended. The complexity 



DliC.HAR.OINO. 



f I <VAl_ ARC. 



FIG. 98. Diagram to illustrate different possible channels of cerebral response 

 to stimulation, and to show how, through reflex action of the lower arcs, 

 the action of the higher arcs may be simulated. 



of the cerebral action in the higher animals has its basis in 

 the greater number of distinct impressions which have been 

 received and reacted to. Each separate stimulus leaves its mark 

 upon the brain, or, as we may say, is stored in the brain, and each 

 subsequent similar stimulus is sent into these channels, or is 

 associated with the past reactions, and thus the present response 

 is determined. For appropriate reaction the whole mechanism 



