CH. XLVIIL] 



LOCALISATION IN MONKEY'S BRAIN 



685 



FIG. 496. 



number of circles, stimulation of each of which produced movements 

 of various sets of muscles, face, arm, and leg from below upwards ; 

 extirpation of these same areas produced the corresponding paralysis 

 It will be further noticed 

 that these areas are all 

 grouped around the fissure 

 of Eolando, particularly 

 in the ascending frontal 

 and ascending parietal con- 

 volutions ; hence the term 

 Rolandic area which is 

 often applied to this 

 region of the brain. 



Most of our know- 

 ledge concerning the locali- 

 sation of the sensori -motor 

 area in the human brain 

 has been deduced from ex- 

 periments on the lower monkeys. 

 Valuable as such knowledge is, 

 infinitely more useful knowledge, 

 from the standpoint of the human 

 brain, would be obtained by 

 examining the brains of those 

 monkeys nearest to man, which 

 are known as the anthropoid apes. 

 The difficulty and expense of ob- 

 taining such animals has hitherto 

 deterred investigators from per- 

 forming such experiments. Hor- 

 sley and Beevor examined the 

 brain of an orang-outang some 

 years ago, and now Sherrington 

 and Griinbaum have made a 

 number of experiments; several 

 specimens of two species of chim- 

 panzee, the orang and the gorilla, 

 have been examined. Their con- 

 clusions are of great importance. 

 The figure on p. 687 (fig. 498) 

 of the chimpanzee's brain shows 

 what has been found ; the orang 

 and the gorilla gave practically the same results, and no doubt the 

 human brain would give identical results also if it could be examined. 



The method used is to expose the brain in an anaesthetised animal, 



FIG. 497. 



FIGS. 496 and 497. Diagrams of monkey's brain 

 to show the effects of electric stimulation of 

 certain spots. (According to Ferrier.) 



