OLD AGE. 



327 



The records show a similar distribution of loss in the 

 two sexes, though it is absolutely greater in the males 

 than in the females. Especially heavy is the loss in the 

 frontal lobes of the males. Expressing these absolute 

 figures as percentages, the weight of the entire ence- 

 phalon in each sex being represented by 1,000, the 

 results shown in Table 60 are obtained. 



TABLE 60. GIVING THE PERCENTAGE VALUES (NUMBER OF 

 PARTS IN 1,000) OF THE ABSOLUTE FIGURES IN TABLE 59, 

 ARRANGED ACCORDING TO SEX AND AGE. (Broca.} 



The proportions of the cerebrum thus divided are 

 nearly the same for both sexes at the two age periods. 

 The most marked difference is in the temporo-parietal 

 lobes, the proportional value of which in both sexes 

 decreases 1*5 per cent, with advanced age. The occi- 

 pital lobes in the aged are something more than I per 

 cent, heavier. In the male, age produces a proportional 

 decrease in the weight of the frontal lobes, whereas in 

 the females there is an increase. Of changes in the 

 weight of the spinal cord nothing is known, neither are 

 there any studies of old age in animals which illustrate 

 the changes in the nervous system. 



