Chap, it.] 



THE BEAIK 



741 



of the region leads to particular movements carried out by par- 

 ticular muscles. For instance, stimulation of the more median 

 parts of the gyrus behind the crucial sulcus (Fig. 121 JJ) leads 

 to movements of the hind limb, whereas stimulation of the lateral 

 part or outer end of the same gyrus leads to movements of the 

 fore limb, and we may here distinguish between an area stimu- 

 lation of which (Fig. 121 +) leads to flexion of the fore limb, 

 and an area (Fig. 121 +) stimulation of which leads to exten- 

 sion of the same limb. In a similar way stimulation of other 



Fig. 121. The Areas of the Cerebral Convolutions of the Dog, accord- 

 ing TO HlTZIG AND FrITSCH. 



(1) A The area for the muscles of the neck. (2) + The area for the exten- 

 sion and adduction of the fore limb. (3) + The area for the flexion and rota- 

 tion of the fore limb. (4) 11 The area for the hind limb. Running transversely 

 towards and separating (1) and (2) from (3) and (4) is seen the crucial sulcus. 

 (5) O The facial area. 



areas within the 'motor' region leads to movements of this kind 

 or of that kind of the tail, of the eyes, of the mouth, of other 

 parts of the face, of the tongue, and so on. Obviously in the 

 dog this region of the cortex has connections with the skeletal 

 muscles which do not obtain between other regions of the cor- 

 tex and those muscles; and further, the region in question is 

 topographically differentiated, so that certain areas or districts of 

 the region are specially connected with certain skeletal muscles 

 or groups of muscles. We may speak of a ' localisation of func- 

 tion ' in this region as compared with other regions of the cortex, 

 and in the several areas within the region as compared with 

 each other. 



The muscles which are thus thrown into contraction are the 

 muscles of the opposite side of the body. When ' the fore limb 



