WEIGHT OF THE BRAIN. 



179 



the female. In these cases the deaths were the result of more or less prolonged 

 disease ; but in six healthy individuals dying suddenly from disease or accident, 

 the average proportion was 1 to 41. 



The proportionate weight of the brain to that of the body is much greater at 

 birth than at any other period of extra-uterine life, being, according to Tiedemann, 

 about 1 to 5 '85 in the male, and about 1 to 6 '5 in the female. From various 

 observations, it further appears that the proportion diminishes gradually up 

 to the tenth year, being then about 1 to 14. From the tenth to the twentieth year 

 the relative increase of the body is most striking, the ratio of the two being at the 

 end of that period about 1 to 30. After the twentieth year the general average of 

 1 to 36 '5 prevails, with a further trifling decrease in advanced life. 



Influence of stature on brain tveight. According to J. Marshall, the proportion 

 of entire brain (in ozs.) to each inch of stature, is for the male sex 0'708 ; in 

 the female 0'688. This relative preponderance in the male is due entirely to pre- 

 ponderance of cerebral development ; the average stature-ratio for cerebrum alone 

 being 0'0619 oz. in the male per inch of stature, and (V599 oz. in the female, 

 whils t the stature-ratios of cerebellum, pous and medulla oblcngata, are similar in 

 the two sexes. 



The following tables have been compiled by Marshall from the data furnished by 

 the observations of K. Boyd upon the brains of 1150 sane persons, viz. : 598 males 

 and 552 females. They show the average weights in ozs. of the encephalon and its 

 several parts at certain periods of life and in individuals having certain differences 

 of stature : 



MALES. 



FEMALES. 



N 2 



