959 



Betz, when first describing these large pyramidal cells, suggested thatthey 

 were related to some motor function, and this view was a few years later 

 more clearly developed by Lewis, the real pioneer in cortical localization 

 by the histological method. He mapped out the motor area in man 

 by this method, and his results differ surprisingly little from those of 

 Campbell obtained by a much more elaborate technique. He pointed 

 out that areas containing the giant pyramids corresponded with a 

 number of the areas defined as motor areas by the experimental 

 physiologists by means of electrical excitation. Definite proof of 

 the connection of the Betz cells with the pyramidal fibres was not 

 obtained till much later. Some of the facts which have established 

 such a connection are alluded to on a previous page (p. 875). Other 

 characters than the size, shape and distribution of the nerve cells 



, * 



V 



Fig. 388. Cell-Lamination of Gyrus 

 Precentralis (Campbill). From the 

 portion of the gyrus immediately 

 in front of the central sulcus (Camp- 

 bell's precentral area in Figs. 390, 



Fig. 389. Cell-Lamination of Gyrus 

 Precentralis (Campbell). From an- 

 terior part of the gyrus (Campbell's 

 intermediate precentral area in Figs. 

 390, 391). 



have also proved of value in differentiating histologically the various 

 regions of the cortex for example, the differences in the diameter 

 and the number of the medullated nerve fibres which run verti- 

 cally into and out of the grey matter. Although the method has 

 yielded valuable and suggestive results, it would be misleading to 

 state that the agreement with the experimental and pathological 

 findings is anything more than a general one. Discrepancies in 

 detail are not lacking, and this might be expected. Histological dif- 

 ferences, after all, are only rough criteria for the differentiation of 

 function. 



Although the results are less definite, the work of Flechsig on the 

 time of development of the medullary sheath of the fibres in the various 

 cerebral convolutions has also contributed to our knowledge of localiza- 



