I9O THE GROWTH OF THE BRAIN. 



sent the grey and white matter at different levels in the 

 enlarged cephalic end, the area of which in the cross- 

 section would of course be many times that of the 

 spinal cord. There is perhaps no more striking feature 

 in the architecture of the mammalian nervous system 

 than precisely this development of the encephalic 

 portion, as compared with either the cranial nerves or 

 the spinal cord. Special interest attaches to this, since 

 there is good reason to consider the better development 

 of the cephalic end as an index of greater intelli- 

 gence. Plain as this fact is in a general way, it is still 

 difficult to express it concisely. For the present the 

 data indicating the weight of the cord, as compared 

 with the weight of the encephalon, are alone available. 

 Though the weight of the human encephalon is superior 

 to that of all but a very few animals, the human spinal 

 cord is surpassed in weight by almost all the larger 

 mammals. This relation, however, varies greatly with 

 age. In man also there is found a change in the 

 weight of the spinal cord, whereby the adult has pro- 

 portionately a larger co/d than the child at birth. This 

 relation is expressed in Table 45. Table 46 shows the 

 relation of the cord to the brain in a series of mammals 

 at birth and maturity. 



TABLE 45. SHOWING THE WEIGHT OF THE SPINAL CORD AS 

 COMPARED WITH THE ENCEPHALON IN MAN AT DIFFERENT 



AGES. (Compiled from Mies.} 



WEIGHT OF SPINAL CORD. WEIGHT OF ENCEPHALON. 



Males. Females. 



Foetus 3 months i 18 



5 i ioi 



At Birth i 116 113 



In Adults ... 



49 



