GROWTH OF THE CEREBRAL CORTEX 
TABLE 14. 
109 
Comparison of the Norway rat brain with the albino rat brain of like weight for the 
numbers of nerve cells in the lamina pyramidalis and in the lamina ganglionaris 
and the number of ganglion cells only in the lamina ganglionaris, in a unit volume 
of 0.001 mm.3, and also for N, which is the sum of the numbers in the lamina 
The data were taken from tables 
pyramidalis and in the lamina ganglionaris. 
3 and 10 
NUMBER OF CELLS IN A UNIT VOLUME N, 
OF CORTEX, 0.001 mM.3 THE SUM OF 
; NUMBERS 
weit Ganglion ae aL ee os 
BRAIN WEIGHT GROUP Lam. pyram.| Lam. gangl. | cells in lam. AND IN 
gangl. LAM. GANG. 
Al- Nor- | Al- Nor- | Al- | Nor- | Al- Nor- | Al- | Nor- 
bino | way | bino | way | bino | way | bino | way | bino | way 
grams| grams 
Xai AES) AS 07 73 74 23 19 | 186 | 181 
XID 1.253 108 68 23 171 
SGUGL 1.335]1.369| 99 96 Ue 7 25 19 | 176 | 166 
XIV 1.445}1.430| 94 92 71 68 25 19 | 165 | 160 
XV 1.554|7.546| 87 83 62 61 23 20 | 149 | 144 
Nevall 1.656|1.629) 84 80 60 58 24 20 | 144 | 138 
XVII 1.726|1.739| 83 76 63 56 25 21 | 146 | 132 
XVIII 1.839/1.829| 79 7 59 56 23 21 | 138° || 138i 
XIX 1.92417.972| 81 73 51 54 24 20 | 1382 | 127 
xx 2.054/2.052| 80 72 51 b1 20 He) | Mesh || aes 
XxI 2.172 68 44 iG 112 
Average for Groups 
OTIS XOX eee nants 1.692:1.695| 86 81 62 | 60 24) 20] 148 | 140 
lower in the Norway rat, if the brain weight be selected as a 
standard of comparison. 
R. The computed volume of the entire cerebral coriex. Norway rat 
compared with the Albino 
The computed volume of the cerebral cortex for the Norway 
may also be obtained and expressed in values comparable among 
themselves, by the use of the formula: L. F x W.D x T (where 
T’ denotes the mean thickness of the cortices in the sagittal and 
the frontal sections), as already explained in detail in part I 
(see p. 82). But for a comparison between the cortical volumes 
of the Norway and of the Albino brains, the direct comparison 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 29, NO. 2 
