THE BRAIN 133 



are farther removed from both muscles and sense- 

 organs. They are known to be late in their develop- 

 ment. The more extended and subject to change the 

 paths from simple sensory to primitive motor centers 

 the more variation we may expect to observe in the 

 conduct of an animal the more spontaneous and the 

 less machine-like it will appear. Every such path is 

 supposed to lie through association areas. In the 

 striking out of these paths there is the greatest possibility 

 for individual divergence. 



In the human brain one of the great association areas 

 lies in the frontal region and another in the parietal. 

 There are doubtless many other parts of the cortex, 

 of less extent than these, which have the same char- 

 acteristic: that is, absence of direct connection with 

 the brain-stem. Disease, when limited to such parts 

 of the cortex, does not produce clear and definite symp- 

 toms, like paralysis, blindness, or deafness. It is more 

 likely to result in indefinite but serious loss of intelligence. 

 Sometimes we hear of a wonderful preservation of all 

 the faculties in spite of gross injuries by gunshot wounds 

 or otherwise. When we consider the fatal effects com- 

 monly following brain injuries we must bear in mind 

 that, when the skull is penetrated, pressure and dis- 

 placements of tissue may occur at some distance from 

 the apparent seat of the damage. 



When we compare ourselves with the lower animals 

 we are apt to think most of our psychic life. Beyond 

 question we are right in doing so but the physiologist, 

 anxious to keep objective standards so far as he may, 

 will say that we are distinguished by our varied reac- 

 tions. The brain of man is adapted to execute these 

 responses, to blend them, and also to suppress certain 

 ones in favor of others. This last is a function of the 

 utmost significance. 



Cerebral Inhibition. If we reflect a little upon what 

 constitutes strength of character we realize that the 

 man we admire does not do various things which a 



