744 



CORTICAL MOTOR REGION. 



[Rook hi. 



of the monkey, leading up as they do to those of man, call for 

 special notice. 



§ 484. When in a monkey, in an individual for instance 

 belonging to the genus Macacus, the surface of the cerebrum is 

 explored with reference to the effects of electric stimulation, it is 

 found that when the current is applied to the precentral or 

 ascending frontal and the post-central or ascending parietal 

 convolutions which lie respectively in front of and behind the 

 important central fissure or fissure of Rolando (cf. Fig. 122), 



Fig. 122. Outline of Brain of Monkey (Macacus) to shew principal 

 Sulci (Fissures) and Gyri (Convolutions). (Natural size.) (Sherring- 

 ton after Horsley and Schafer.) 



The brain figured is the same as that in Fig. 123, and the two figures should 

 be consulted together. Over each sulcus, purposely printed very thick, the name 

 is written in small capitals, over each gyrus in italics, x indicates the small 

 depression, hardly to be called a sulcus, which is supposed to be homologous with 

 the superior frontal sulcus of man ; and iv, y, z similarly indicate sulci whose 

 homologies are not certain. For some synonyms see Figs. 134, 135. 



movements of the fore limb follow. The ' motor area for the 

 fore limb ' thus discovered is more circumscribed and definite 



