356 THE SIZE AND WEIGHT 



The difference between the average weight of the male 

 and female brain, according to Welcker's computation, is 

 4-94 oz. or 140 grmm. ; but according to Dr. Peacock's 

 observations on the Scotch, 5*3 oz. or 150 grmm. 



Thurnam says : 



" Some have supposed with Tiedemann that the less size of the 

 brain of the female is due simply to her less stature. This, how- 

 ever, is not the case ; and it was long ago shown by M. Parchappe, 

 though from a too restricted number of weights, that the difference 

 was greater than could be accounted for in this way. I am able to 

 confirm this opinion from calculations founded on the great tables 

 of Dr. Boyd for St. Marylebone. For this purpose I have examined 

 and compared the average stature and brain-weight for men and 



women at the decennial periods from twenty to sixty 



Whilst the brain-weight is nearly 10 per cent, less in the female 

 than in the male, the stature is only 8 per cent. less. " 



Weight of Body and Stature. The ratio of Brain- 

 weight to body- weight follows almost precisely the same 

 laws as have been found to hold for lower animals ; that 

 is, the ratio diminishes with increasing weight and stature 

 of body, so that, as Tiedemann observed, "the human 

 brain is smaller in comparison to the body the nearer 

 man approaches to his full growth." 



It varies also with his degree of obesity. "In lean per- 

 sons the ratio is often as 1 : 22 to 27 ; in stout persons as 

 1 : 50 to 100." 



But, as Thurnam says : " Though it may be ques- 

 tioned whether many useful physiological inferences are 

 to be deduced from the ratio of the brain-weight to that 

 of the body in the two sexes, the comparison of the brain- 

 weight with the stature may yield more valuable conclu- 

 sions. . . . Parchappe inferred that, other things being 

 equal, the weight of the brain in both sexes is relatively 

 greater in tall persons than in short ones, the difference 



