35 THE GROWTH OF THE BRAIN. 



the cerebral cortex in order to determine whether growth 

 there practically ceased at puberty ; for, by contrast, 

 Venn, studying the size of the head in Cambridge 

 students, found it on the average greatest and growing 

 for the longest time in the group of most successful 

 men. The accomplishments of this fortunate group are 

 therefore to be associated with innate capacities, and 

 have small ethical significance ; they may be admirable, 

 just as are the paces of a well-bred colt, but the 

 colt deserves no credit for its gait. Indeed the obser- 

 vations of Ranke just quoted, stand as an anthropo- 

 logical verification of that tendency so to use our 

 native endowments as to get from them all the stimu- 

 lation of which our sensory systems are capable. It is 

 a deeply seated impulse. The defective sense organ or 

 the paralysed limb are often treated very roughly in 

 the vain hope of getting a sensation from them. It 

 would appear that the parts of the nervous system cut 

 off from their normal stimuli may, so long as they are 

 alive, cause their owners much discomfort, and these 

 individuals resort to indirect means to get rid of 

 the irritation. 1 The obverse of this appears in the 

 " breaking out " experiences so common in all commu- 

 nities of growing individuals. In prisons, schools, and 

 similar institutions, where hard physical exertion is not 

 compulsory, or the routine is deadly monotonous, such 

 explosions are bound to occur. Some years ago, when 

 college athletics were coming into vogue, Professor 

 Richards, of Yale, pointed out that college rows and 

 disorders fell off as athletics came in. 2 It is not easy 

 to make experiments of this sort, but there is no doubt 

 that during the growing period this surcharging, though 



1 Weir- Mitchell, Injuries oj Nerves and their Consequences, 

 Philadelphia, 1872. 



2 Richards, Pop. ScL Month., 1884. 



