Chap. XX.] OF THE HUMAN BRAIN. 871 



relation between the degree of Intelligence of human 

 beings and the mere size or weight of their Brains. 

 We have seen that some demented persons may have 

 very large brains ; and again, that in certain very ordinary 

 members of society, suffering neither from disease nor 

 from congenital defect, the brain may be decidedly large 

 and heavy. On the other hand men of great acquire- 

 ments, of acknowledged mental power, and one or two 

 even of European fame, may have been, whilst in their 

 prime, possessed of brains either below or only slightly 

 exceeding the average weight of the male brain in civilized 

 races, viz., 49 oz. — showing that a well- constituted Brain of 

 small dimensions may be capable of doing much better 

 work than many a larger organ whose internal constitution 

 is, from one or other cause, defective. 



Looking, in fact, to the mere size and weight of a 

 Brain, it must never be forgotten that these may be 

 notably augmented by overgrowth of its mere inert con- 

 nective tissues; or even if morbid tissue changes be 

 absent, that an organ of large size or weight may yet be 

 a more or less inferior perceptive or thinking instrument 

 by reason of its inner and finer developments being 

 defective and badly attuned for harmonious action. Or 

 again, it may be a defective instrument by reason of some 

 still more subtle, and mere molecular peculiarities of the 

 nerve elements of which it is composed — whereby these are 

 perhaps both less receptive and less ' retentive ' of those 

 Sensorial Impressions which constitute the raw material 

 of Intelligence, and also less capable than they might be 

 of taking part in higher Mental Operations. 



There is, therefore, no invariable or necessary relation 

 between the mere Brain-weights of individuals and their 

 degrees of Intelligence. But should it be asked whether 

 the proportion of megalocephalous Brains among highly 



