A STUDY OF THE LOCATION AND ARRANGEMENT OF THE 

 GIANT CELLS IN THE CORTEX OF THE RIGHT HEMI- 

 SPHERE OF THE BONNET MONKEY (MACACUS SINI- 



CUS). 



BY 



E. LINDON MELLUS. 



From the Anatomical Laboratory of the Johns Hopkins University. 



With 3 Figures. 



In view of the recent experimental results regarding the representation 

 of movements in the cerebral cortex, a more exact study of the distri- 

 bution of the large pyramidal cells as seen in microscopic sections has 

 seemed to me desirable. The following paper deals with the distribu- 

 tion in the bonnet monkey. 



The right hemisphere of a healthy adult monkey (Macacus sinicus) 

 hardened in Miillers fluid, dehydrated and imbedded in celloidin, was 

 cut in horizontal sections 50 microns thick. The sections were num- 

 bered from below upward, and stained first by Pal's modification of 

 Weigert's hematoxylin method, counter-stained with - carmine and 

 mounted in balsam. This double stain has the advantage of accentuat- 

 ing the contrast between cells and fibers and facilitating the study of 

 the relation of the cells to the various fiber tracts. 



A careful study of these serial sections reveals the following arrange- 

 ment of the Betz (giant) cells in the motor cortex and, if confirmed by 

 the study of their disposition in other specimens, may lead to some 

 modification of the present ideas in relation to the extent of the so-called 

 " motor areas of the cortex. 



On the external surface of the hemisphere the lowest point at which 

 any giant cells are found corresponds to the lower extremity of the 

 fissure of Rolando. A few scattered cells are found here upon the an- 

 terior lip, but quite in the depth of the fissure. From this point upward 

 they gradually increase in number and at a point about 0.5 mm. higher 

 up there is a small group of giant cells between the corona radiata of 

 the ascending frontal convolution and the surface, but the majority of 

 these cells is still within the fissure contiguous to what may be called 

 the posterior aspect of the corona radiata of the ascending frontal con- 



American Journal of Anatomy. — Vol. IV. 



