HOW THE BRAIN THINKS 



directly with the size and weight of the body. It 

 is obvious that a big body will need a big brain to 

 run it right, for nine- tenths of nervous activity or 

 "mental" action is devoted to the promotion and 

 control of the muscles. A little man with a big 

 head, then, is apt to possess more of what we call 

 brains than a big man with a relatively small head. 



But there seems another anatomical character- 

 istic of far more importance than size. That is the 

 appearance of the brain surface the cortex, or 

 rind. When the brain of a highly developed man 

 or woman is examined, it is found to be creased 

 and folded in an extraordinary way, thrown into 

 convolutions, as the neurologists say. And so 

 it seems as if "brains" are a matter of area of 

 brain surface, for the effect of the folding and 

 creasing is to afford more area in a given space. In 

 the matter of brain anatomy it is the superficial 

 man, then, who is the great man. And, in general, 

 the more folds and kinks he has the greater will 

 he be. 



But it is not until we penetrate into the finer 

 structure of the brain that we begin to catch a 

 glimpse of the mechanism of brain-action. Count- 

 less attempts had been made to unveil this com- 

 plicated structure, but it was not until an Italian, 

 Professor Golgi, took up the matter, about twenty 

 years ago, that any real progress was made. Pro- 



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