GROWTH OF THE CEREBRAL CORTEX 



555 



0.1 Q2 03 0.4 0.5 05 QT 08 09 I.O 11 12 13 14 1.5 lb 17 18 19 20 



Chart 2 Giving for each brain weight group, in millimeters, on brain weight 

 in grams, the values for the several diameters. W. B. and W. D., width; L. F. and 



L. G., length; Ht., height. • • = W. B. • • = IF. D. O O = L. G. 



O 0=L.F. X X = Ht. 



where EF is the longitudinal diameter in the plane of the sagittal 

 section (fig. 12). The thickness of the cortex at localities I-V 

 was corrected by the use of this coefficient. 



For the frontal section the corresponding formula is 



n = Ts X 



W.D (freshj 

 W.D (on slide) 



(2) 



where CD is the width in the plane of the frontal section (fig. 

 12). The thickness of the cortex at localities VI, VII, and VIII 

 was corrected by the use of this coefficient. Of course, the actual 

 measurement on the slide was in this section that of one hemi- 

 sphere only. The observed value obtained was therefore doubled 

 for use in the formula. 



After considering several possibilities, I decided to use for 

 horizontal sections, the value for the maximum width of the 

 brain, AB, in order to obtain the necessary formula. Thus, 



