STUDIES OF CEEEBRAL FUNCTIOISr IN LEARNING. VII 6 



remains in doubt. It is probably, as Lapicque ( '23) suggests, 

 an adaptation for nutrition of the cortex and as such should 

 depend more upon the absolute size of the brain than upon 

 its complexity of organization. 



More certain evidence of the significance of ganglion cell 

 number appears in the cyto-architectural studies of Bolton 

 ('14) and Southard ('14). They have found a general reduc- 

 tion in the number of functional ganglion cells in amentia 

 and dementia, but the limit to which cell degeneration can 

 occur without mental deterioration is not determined, nor is 

 it certain that the symptoms in these disorders are due to the 

 reduction in cell number, and not to invisible changes in the 

 remaining functional cells. 



Students of gross injuries to the cerebrum have been so 

 occupied with problems of cerebral localization that the pos- 

 sibility of quantitative relationships has been largely over- 

 looked. The theory of localization of faculties has worked 

 fairly well for sensory projection areas and motor areas, but 

 the clinical literature contains many so-called negative cases 

 which fail to conform to any schema of localization. In par- 

 ticular the association areas have given difficulties. Reported 

 effects of lesions in them are contradictory and in many cases 

 questionable. Much of the difficulty here may be due to 

 failure to take into consideration the extent of the lesions 

 as well as their locus. Bianchi ('22) holds that marked de- 

 terioration occurs only after very extensive lesions in the 

 frontal areas, and Monakow ('14), in discussion of aphasia, 

 points out that severe and permanent symptoms occur only 

 after extensive or diffuse lesions. Beyond the suggestion of 

 this critical amount of injury for the production of severe 

 symptoms, the clinical literature gives no consideration to 

 the problem of cerebral mass. 



Taken altogether, these lines of investigation point to a 

 relationship between neural mass and complexity of behavior, 

 but there is little suggestion of the reason for this relation- 

 ship or of the real degree of correspondence. Attempts to 

 localize intelligence in any particular part of the brain, as in 



