CHAP. XX.] OF THE HUMAN BRAIN. 375 



regions of the brain whose action is inseparably related 

 to the mental phenomena in question. 



The ievelopment here referred to is of the finer sort ; 

 that which, to some extent, eludes our present means of 

 observation. Its establishment may be associated with 

 an altogether insignificant increase of weight, and perhaps 

 no increase in size, of the organ as a whole. Yet a 

 development of previously embryonic Nerve Cells, together 

 with an establishment of multitudinous new connections 

 between them, by means of ' intercellular processes ' and 

 ' commissural fibres,' may have been taking place through- 

 out large tracts and areas of the Brain, to an extent which 

 it is altogether impossible for us adequately to realize.* 



That this is no mere fancy is in part evidenced by other 

 facts previously stated, viz., that the male brain actually 

 attains -fths, and the female brain y-fths of its total 

 ultimate weight by the end of the seventh year although, 

 at this time, the inner and finer structural development 

 of the organ is, in all its higher tracts, still in a com- 

 paratively embryonic condition. Even such data might, 

 therefore, be considered to show, in the strongest manner, 

 how comparatively unimportant is mere bulk or weight of 

 Brain in reference to the degree of Intelligence of its 

 owner, when considered, as it often is, apart from the much 

 more important question of the relative amount of its grey 

 matter, as well as of the amount and perfection of the 

 minute internal development of the organ either actual or 

 possible. 



* See p. 346, for the statement made by Lockhart Clarke as to 

 the characteristics of the embryonic or undeveloped nerve ele- 

 ments met with in the Cerebral Convolutions of the foetus. 



