528 NAOKI SUGITA 



The area EE'~FF' represents the subiculum cornu Ammonis. 

 The cortex consists of a thick lam. zon., the lam. gang, which 

 has again resumed its former breadth, and the very thin lam. 

 mult. At FF' the pyramids of the lam. gang, come more closely 

 together, and the breadth of the layer diminishes remarkably, 

 the cells arranging themselves in about three or four rows, as 

 they pass over to the specific ganglion cell layer of the cornu 

 Ammonis. 



Figure 2 shows also the positions of the localities at which the 

 thickness of the cerebral cortex was carefully measured. These 

 localities have been so selected as to be fairly representative of 

 the entire cortex as regards thickness. 



Locality I. On the line of /-/', drawn through the frontal tip 

 and running parallel to the radiation of the ganglion cells, the 

 diameter /-/' is measured, between the outer limit of the lam; 

 zon. and the inner border of the lam. mult. As a matter of fact, 

 the cell-radiation in this locality is not exactly in a straight line, 

 but somewhat bent, owing to the rapid curvature of the cortex 

 and its great thickness. Notwithstanding this, I have measured 

 the thickness of the cortex by a straight line, as indicated above. 

 The thickness at /-/' is the greatest found in this study. 



Locality V. The thickness V-V is measured at a point some- 

 what cephalad to the occipital pole, on the line directed along the 

 cell-radiation. I thought it would be more advisable to measure 

 the occipital cortex not exactly at the tip of the occipital lobe, 

 but somewhat cephalad, thus making the direction of the line 

 V-V not very divergent from the direction of the line IV-IV , 

 if not parallel to it. The locality chosen {V) seemed suitable 

 and has been used throughout. The thickness at V~V' repre- 

 sents the thinnest part of the cortex. 



Locality III is midway between localities I and V and falls 

 nearly in the middle of the area BB'-CC , the area in which the 

 largest pyramidal cells appear. The locality is marked by the 

 line III-III' , drawn perpendicular to the cortex and tangent to 

 the ganglion-cell band at the frontal tip of the cornu Ammonis. 



Locality II. The line at II-IF runs parallel with the radiat- 

 ing cells and lies midway between the localities I and III. The 



