356 NERVOUS SYSTEM OF VERTEBRATES. 



the symptoms which appear during life involve loss of appreciation 

 of the individual's personality and of the value of things to him. 

 Self-depreciation and lack of confidence or the opposite extremes, 

 incapacity for moral and aesthetic judgment, uncertainty of 

 action and lack of will, are common in such persons. Their 

 self-control suffers and under the influence of excitement their 

 conduct becomes immoral or criminal. The anterior association 

 field has to do, then, with ideas of the individual's personality and 

 with the appreciation of his personal relations. For conduct in 

 the full sense, that is for moral conduct, there is required the normal 

 functioning of both anterior and posterior association fields; since 

 both objective and- subjective relations must be considered, both 

 judgment and will are involved. For moral conduct the individ- 

 ual must respond to both the external or objective and the individ- 

 ual or subjective factors in his situation, and the perfection of the 

 response depends upon the grade of organization of the association 

 centers and the balance between them. 



THE EVOLUTION OF THE NEOPALLiUM. The general subject of 

 the origin of the neopallium has been considered in the last chapter, 

 but a certain interest attaches to the order and grade of develop- 

 ment of its various parts. The direct data for the study of these 

 subjects are very meager. The collection of such data would 

 require the study of cerebral localization in the various orders of 

 mammals together with the study of habits and the grade of organ- 

 ization of intelligent action. Such studies are not yet complete 

 enough for this purpose but the facts of localization in the human 

 brain give some indications of the probable course of development. 

 First, the facts that the senso-motor areas are everywhere separated 

 by association areas and that myelinization proceeds from the senso- 

 motor areas into the association areas warrant the inference that 

 the association areas have been differentiated from the borders of 

 already existing senso-motor areas. The senso-motor areas 

 must have occupied the greater part or the whole of the neopallium 

 in lower mammals and the greater size of the hemispheres in 

 higher mammals is due chiefly to the expansion of the association 

 areas. Second, the position of the several senso-motor areas 

 indicates the order of development in the neopallium. The phy- 



