VARIATIONS IN BRAIN- WEIGHT. 127 



minimal mass of brain substance which, other things 

 being equal, should be the same in both sexes. It 

 further requires that when the brain- weight increases 

 there should be an increased mental capacity, and 

 finally, since it is found that the average European 

 male has a brain-weight about 120 grammes in excess 

 of that for the female, it is therefore concluded that the 

 male brain has superior powers, of which the 120 

 grammes can serve as a measure. Since among micro- 

 cephalies there is still a distinction in brain-weight 

 according to sex, the current explanation must be con- 

 sidered as incomplete. 



On passing from the microcephalies to other groups 

 in which the weight of the brain is greater, we come 

 into the company of those individuals who are able to 

 make a fairly successful struggle for existence, a capacity 

 which is taken as one measure of the intelligence. It is 

 perfectly plain, however, that a wild life under clement 

 conditions can be met by a far simpler mental organisa- 

 tion than is needed to face town life in the temperate 

 zone, and hence the capacity to lead an independent 

 existence is but a poor standard. 



The observations recorded in the preceding chapters 

 compare average brain-weights (small, medium, and 

 large being taken together) with one another, and show 

 several conditions which influence this average, but as 

 they stand the figures furnish no basis for correlating 

 brain- weight with brain functions. Attempts have been 

 made, however, to get some light on this from the com- 

 parison of the different classes in the community. 

 Take, for example, the brain-weights of eminent men, 

 arranged according to age with omission of certain 

 mythical records like those for Tourgenieff (2,012 

 grammes), Cromwell (2,231 grammes), and Byron (2,238 

 grammes). 



