350 



NERVOUS SYSTEM OF VERTEBRATES. 



^r-^ 



^, ?^- 





Fig. 177. — The primordial areas and the border zones of the association fields, 

 lateral surface. From Flechsig. The figure represents the extent of myelifi- 

 ization in the hemisphere of a newborn infant 54 cm. in length. The primary 

 sense areas and a part of the border zones are myelinated and the numerals indicate 

 the order in which they receive their myelin. The anterior and posterior associ- 

 ation fields stand out sharply as light areas. The middle association field is 

 exposed to view by drawing aside the temporal lobe. 



.^K^.,a 



^ .^ 



10 



Fig. 178. — The primordial areas and the border zones of the association fields, 

 mesial surface. From Flechsig. See Fig. 177. 



