LECTURE III. 87 



of intelligence ; and Broca has shown, from Wagner's table, 

 that, excepting the brain of Hausmann, all the brains of noted 

 or celebrated individuals excelled the average weight of those of 

 unknown persons, and that the brains of Wagner's colleagues, 

 weighed by himself, occupy the first rank in the series, if ar- 

 ranged according to weight. This is a point of very great 

 importance ; for after all, only such brains as have been weighed 

 by the same observer, after the same method, can be compared 

 with each other. A difference of fifty grammes or more may 

 easily be caused by the way in which the brain is prepared ; 

 and in most cases experimenters give no clear explanation of 

 their mode of preparing the brain previous to weighing. Whilst, 

 then, men occupying the same rank of intelligence may have 

 brains of different weights, and privileged individuals may 

 sometimes possess lighter brains than others who are noways 

 distinguished from the common horde, it still remains an 

 established fact that, generally speaking, there is an approxi- 

 mative relation between cerebral weight and intelligence, and 

 that the determination of this relation should on no account 

 be neglected. 



The result of these in^'estigations enables us definitely to 

 assert, that a certain weight of brain is requisite for the mani- 

 festation of intellectual faculties ; that idiocy and mental weak- 

 ness begin below this weight ; and that this weight, as regards 

 the white race, or central European nations, is about a kilo- 

 gramme for the male, and 900 grammes for the female. We shall 

 recur to this point when treating of the relation of idiots with 

 arrested cranial and cerebral development to the simian type. 



I have purposely stated, that the lowest normal weight quoted 

 only applies to the central European peoples ; whether to the 

 white race in general is yet doubtful. The more we specialise 

 in such matters the better; and as it is scarcely determined 

 whether the white race forms really a united whole, or is not a 

 mixture of various species, it is as well to confine ourselves 

 strictly to data before us. Direct investigations relating to 

 other races, which no doubt have their peculiar standard, 

 we do not yet possess. We are necessarily confined, for the 

 present at least, to measurements of the internal capacity of 

 the skull. Even with regard to this, erroneous results were 



