214 



BRAIN-WEIGHT AND SIZE IN RELATION 



49"6 oz., or 1405 grms. ; and of one hundred and twelve male brains 

 from twenty to thirty years of age, giving an average of 48*9 oz., or 

 1384 grms. ; and the results of a nearly equal number of female 

 brains closely approximate. They embrace English, Scotch, German, 

 and French, men and women. Dr. Welcker's results indicate the 

 period of maximum brain-weight to be between 30-40, as shewn in 

 the following table : 



TABLE VI. 



AVERAGE WEIGHT OE THE BRAIN AT DIFFERENT AGES. 



In the female examples, amounting to thirty-one between seventy 

 and eighty years of age, and six between eighty and ninety, the 

 continuous diminution of brain-weight corresponds with the increas- 

 ing age ; but in the male examples, sixty-five cases between sixty 

 and seventy years of ago yield an average brain- weight of 46 ■! oz., 

 while twenty-seven cases between seventy and eighty years of age 

 give 47"9 as the average; falling in the next decade to 43'8. 



It may be inferred from the number of cases pointing to an early 

 attainment of the highest, average brain- weight, not that the brain 

 differs from all other internal organs of the human body in attaining 

 its maximum before the period of puberty, but that physical as well 

 as mental vigour are dependent on the maintenance of a nice equili- 

 brium between the brain and the other organs while in process of 

 development. The observations of Dr. Boyd, including the results 

 of 2,614 post mortem examinations of sane and insane patients of all 

 ages, showed that the average weight of the brain of "still-born" 

 children at the full period was much greater than that of the new- 

 born living child. It is a legitimate inference, therefore, that death 

 in the former cases was traceable to an excessive premature develop- 

 jnent of the brain. Again, when it is shown from numerous cases 



