408 Giant Cells of the Bonnet Monkey 



breadth, while those in the cortex of the ascending parietal convolution, 

 with the exception noted, are from 15 to 22 microns long by 12 to 18 

 microns wide. 



On the mesial surface of the brain the superior border of the cortical 

 area in which the giant cells are found corresponds exactly with the 

 superior border of that upon the external surface; that is, the anterior 

 and posterior borders of this area may be followed directly over from 

 the external convex surface of the brain upon the mesial surface. The 

 area occupied on the mesial surface is a somewhat irregular triangle 

 with its apex corresponding to the upper extremity of the fissure of 

 Eolando and its base directed toward the frontal pole. The giant cells 

 are relatively more numerous upon the mesial surface. Instead of 

 being arranged in a single layer, as upon the external surface, they are 

 more irregularly scattered about in groups of several superimposed 

 layers. Cells of the larger diameters are also relatively more numerous 

 on the mesial than on the external surface. The area extends downward 

 to the calloso-marginal sulcus about 8 mm. below the crest of the hemi- 

 sphere. The cells in the lower portion of this area are less numerous 

 and rather smaller than elsewhere on the mesial surface. 



EXPLANATION OF FIGURES. 

 Note that, for the sake of comparison, Fig. 3 is placed above Fig. 1. 



Fig. 1. External surface of right hemisphere; R. Fissure of Rolando; 8. 

 Fissure of Sylvius; F. Frontal pole"; 0. Occipital pole; AB. Plane of section 

 of Fig. 3. Area of distribution of giant cells is striated. 



Fig. 2. Mesial surface of right hemisphere. C. Calloso-Marginal sulcus; 

 F. Frontal pole; 0. Occipital pole; AB. Plane of section of Fig. 3. Area of 

 distribution of giant cells is striated. 



Fig. 3. Horizontal section at line AB, Figs. 1 and 2, showing- arrangement 

 of giant cells at that level. R. Fissure of Rolando; F. Frontal pole; 0. Oc- 

 cipital pole. 



