VARIATIONS IN BRAIN-WEIGHT. 123 



On comparing the two sexes in the human race, the 

 brain, compared with the entire body, is found to be 

 proportionally heavier in the female than in the male. 

 In this instance the only logical interpretation is that 

 the body is somewhat less developed in the female than 

 in the male, and this we know to be the case from the 

 records on the growth of the muscular system. For this 

 reason no effort will be made to restate the various 

 observations on the proportional development of the 

 brain in the two sexes, or the number of grammes of 

 body substance present for each gramme of brain. In 

 such arguments it is assumed that the smaller the mass of 

 the body over which a unit of brain substance presides, 

 the more efficiently will the body be controlled, and the 

 more intelligent will be the individual. This view is 

 not well grounded. While the large absolute weight of 

 the brain in man as compared with other animals still 

 demands interpretation, it is evident from the foregoing 

 facts that conclusions based upon the proportional 

 development of the brain may be very easily mislead- 

 ing, because the variation in that proportion depends 

 upon differences in body-weight. In reality there is 

 here an extremely complex problem, and although in 

 the estimation of the probable intelligence of any animal 

 both the absolute and relative size of the brain are 

 factors, yet they are but two factors among a large 

 number, and therefore their importance can only be 

 determined after further analysis and comparison. 1 



Returning to the principal question before us, we have 

 to inquire whether from any of the physical characters 

 of the brain the intelligence of the individual can be 

 inferred. By way of introduction it will be necessary to 



1 For a general expression of the percentage weight of the 

 brain in terms of the entire body, consult the tables by Vierordt, 

 given in Chapter III., pp. 69 and 70. 



