326 



THE GROWTH OF THE BRAIN. 



whole story. The eminent men have not only the 

 heavier, but the better organised brains ; this organisa- 

 tion being dependent in part on prolonged growth, a 

 condition which would also tend to defer senescence. 

 For these reasons the time at which decay commences 

 in the least favoured classes is probably early as com- 

 pared with the time in those more happily circumstanced. 

 But here again the incompleteness of the data must be 

 noted. 



Some effort has been made to determine how the 

 several lobes of the cerebrum are affected by the 

 general diminution in its weight. The tables here 

 given have been taken from Topinard. Each cerebral 

 hemisphere, the pia having been removed, was divided 

 (Broca), as shown in Fig. 30. This gives the sub- 

 divisions of the hemispheres, including both basal 

 ganglia and mantle, as presented in the tables which 

 follow. 



TABLE 59. SHOWING THE ABSOLUTE WEIGHT IN GRAMMES 

 OF THE LOBES OF THE CEREBRUM (WITHOUT PlA), 

 ACCORDING TO SEX AND AGE. 



