34:0 NEKVOUS SYSTEM. 



We might compare the weight of the body in Mr. Bradley 's 

 case with that of a child from seven to fourteen years of age ; 

 and at this period of life, according to the tables compiled 

 by Quain, the average weight of the encephalon is 45-96 

 ounces, for the male, and 40*78 ounces, for the female. 1 



The statements just made with regard to the brains of 

 idiots refer to cases characterized by complete absence of in- 

 telligence, and furthermore, probably, by very small develop- 

 ment of the body. On the other hand, there are instances 

 of idiocy, the body being of ordinary size, in which the weight 

 of the encephalon is little if any below, the average. Lehit 

 reports several cases of this kind. In one of these, a deaf- 

 mute idiot, forty-three years of age, a little above the ordinary 

 stature, presenting " idiocy of the lowest degree ; no speech ; 

 almost no sign of intelligence ; no care for cleanliness," the 

 encephalon weighed 48'32 oz. Other cases of idiots of 

 medium stature are given, in which the brain weighed but 

 little less than the normal average. a These facts illustrate 

 the difficulty of subordinating individual observations to any' 

 general rule, and this is particularly marked with regard to 

 the brain, the structure of which is so complex and difficult 

 of investigation. 



Comparative Development of the Cerebrum in the Lower 

 Animals. It is only necessary to refer very briefly to the de- 

 velopment of the cerebrum in the lower animals as compared 

 with the human subject, to show the connection of the hemi- 

 spheres with intelligence. In man, the cerebrum presents an 

 immense preponderance in weight over other portions of the 

 encephalon ; and in some of the lower animals, the cerebrum 

 is even less in weight than the cerebellum. In man, also, not 

 only the relative but the absolute weight of the brain is greater 

 than in lower animals, with but two exceptions. Todd cites 



1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 569. 



2 LELUT, Du poids du ccrveau considere dans ses rapports avec le developpement 

 de T intelligence. Physiologic de lapensee, Paris, 1862, tome ii., p. 308. 



