CHAP. vi. 



THE BRAIN. 



625 



one side of the brain only is used. On this point however we 

 must not dwell now; we cannot here discuss the question of 

 unilateral cerebral activity, or the exact nature of the failings 

 which lead to the loss of, or to errors in, speech, or with what 

 particular link or links in the chain of cerebral events leading 

 to speech, whether mainly afferent or mainly efferent ones, this 

 portion of the cortex is associated ; we simply quote these cases of 

 aphasia, as affording proof of the localization of function in the 

 cerebral cortex. 



FIG. 84. 



THE ABEAS OF THE CEBEBRAL CONVOLUTIONS or THE DOG, ACCORDING TO 

 HITZIG AND FBITSCH. 



(1) A The area for the muscles of the neck. (2) -p The area for the extension 

 and adduction of the fore limb. (3) + The area for the flexion and rotation of the 

 fore limb. (4) {: The area for the hind limb. Kunning transversely towards and 

 separating (1) and (2) from (3) and (4) is seen the crucial sulcus. (5) Q The facial 



For a while then the teachings of pathology and experiment were 

 contradictory ; but continued experimental inquiry shewed that the 

 former were in the right. Hitzig and Fritsch were the first to shew 

 that the local application of the constant galvanic current to par- 

 ticular convolutions and to particular parts of convolutions gave rise 

 to definite coordinate movements of various groups of muscles. Thus 

 while the stimulation of one spot (Fig. 84) caused movements in the 

 muscles of the neck, another caused extension with adduction of 

 the fore leg, a third movements of the hind leg, a fourth movements 

 of the eye and other parts of the face. In fact, they and Ferrier, 

 who using chiefly the interrupted or faradaic current, repeated and 

 extended their observations, were able to map out the convolutions 

 of the front and middle parts of the hemisphere of the dog (Figs. 84, 

 85), cat, monkey (Figs. 86, 87), and other animals, into a number 



F. 



40 



