CH. L.] THE CHIMPANZEE'S BRAIN 731 



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 obtaining such animals has largely deterred investigators 

 from performing such experiments. Horsley and Beevor examined 



Anus b.vagina. 

 Toes ,.<'' SidciLs 



Ank(e \ ,*/" /centralis Abdomen 



knee '^^.^^J^.^^r^ ^.Chest 



Fingers 

 b thumb... 



fy* 1 '* /Closure 



Hose of iaw^ , . . , ^^ . ^^ 



*&* Vocal SulcU * Centr&Us 



cord& Mastication 



Fm. 450. Brain of Chimpanzee. Left hemisphere viewed from side and above so as to obtain the 

 configuration of the Rolandic area. The figure involves some foreshortening about both ends of 

 the sulcus centralis or fissure of Rolando. The extent of the so-called motor area on the free 

 surface of the hemisphere is indicated by black stippling which extends back to the central sulcus. 

 Much of the " motor " area is hidden in sulci ; for instance, it extends into both the central and 

 precentral sulci. The names printed in capitals on the stippled area indicate the main subdivisions 

 of the "motor" area; the names printed small outside the brain indicate by their pointing lines 

 some of the chief subdivisions of the main areas. But there is much overlapping of the areas which 

 it is not possible to indicate in a diagram of this kind. The shaded regions marked " eyes " in the 

 frontal and occipital regions indicate the areas which under faradisation yield conjugate movements 

 of the eyeballs. S.F. = superior frontal sulcus. S.Pr. = superior precentral sulcus. I. Pr. = inferior 

 precentral sulcus.g( After Sherrington and Griinbaum.) 



the brain of an orang-outang some years ago, and now Sherrington 

 and Griinbaum have made a number of experiments ; several speci- 

 mens of two species of chimpanzee, the orang and the gorilla, have 

 been examined. Their conclusions are of great importance. The 

 above figure (fig. 450) of the chimpanzee's brain shows what has 

 been found; the orang and the gorilla gave practically the same 



