781 



the cortical breadth, while in area 22 they are of the same breadth 

 as ihe lower three layers. 



Besides the corresponding layers in the two areas still show 

 individual differences in breadth. 



I became convinced that great care is necessary in estimating the 

 relative breadth of the layers. The influence of the convexity and 

 concavity of the cortex on the breadth of the different layers is so 

 considerable that the mentioned difference in breadth-ratio may be 

 the result of this cause alone as well in the one area as in the other. 



From Dr. Droogleevb^r Fortuyn's pieparations and from my own 

 series in conjunction with the liteialure, I arjived at the following- 

 conclusions : 



1. Ii is superfluous to divide Heschl's convolutionfs) into two 

 areas 41 and 42. This area is indicated by 41 -f- 42. 



2. For distinguishing between area (41 and 42) and area 22 the 

 number of giant ceHs is of particular importance. 



Besides these points the greater richness in large pyramidal cells of 

 the III'i layer of area 22 must be noted. 



Differences in breadth-ratio, as are mentioned by Rosenberg, 1 also 

 found in my preparations, although not so conspicuously. For the 

 reasons, mentioned above, however, 1 do not attach so much 

 importance to them. 



The accompanying figures 3 and 4 are typical for areas (41 -(- '^2) 



Fig. 1. Left temporal lobe. Madurese brain A. 

 and 22. They were taken from Dr. Droogleever Fortuyn's paper. 

 In figure 3 three giant cells are seen. 



56 

 Proceedings Royal Acad. Amsterdam. Vol. XX. 



