108 NAOKI SUGITA 
These relations are shown in table 14. As for the number of the 
ganglion cells only in the lamina ganglionaris, it is always lower 
by 2 to 6 in the Norway and the highest figure (21) in the Nor- 
way is seen in Groups N XVII and N XVIII, while in the 
Albino the highest figure (25) is attained in Groups’ XIII and 
XIV and again in Group XVII. In the Albino a temporary in- 
crease of cell number in the lamina ganglionaris was seen in 
Groups XIII and XIV, and in my Norway sections a similar 
phenomenon is indicated in Groups N XVII and N XVIII. 
Generally speaking, therefore, the cell density in the cerebral 
cortex, as far as represented by my observations, is slightly 
600 2S : : 
Rees il | eam (ein eal ra 
550 [eee SAEELO SI eX De Se a tea ee 
[oo le "| a ee ee eed eee Tg | 
500 - call ; = - . 
| | | | | | | LWT! 
450 | —— eS eee = oo ee 
| | [a | 
EN ee Ze alee 
pate T | | Tree | | | | | 
| Bue RSs aa CY oak ae gl 
350 == Se | a. oa 
zl ine ol ae a 
500 aes T —— — 
| | | | _L LW! 
250 . 1 - — | +2 
| | | Bee | | | 
200} + === 4== ae a = ——+ 
ee ee | 
150 oe ee a at 
400 MTA real | AS ee al ELE DUE | Sahessnven | 
ao phe ea He id 
50 ae The = | = | = ~ | a eee =a (i 
he tthe | Rea | | 
rate | eee ee emer | ec eae Pas ie he 
4 HL Pal aie) sh be SI EP Tie HSh= Gon Ss] AO Ree gms. 
Chart 4 Showing the computed values for the cortical volume, the volume 
of the cerebrum, the cenn density in two unit volumes and the computed num- 
ber of nerve cells in the entire cortex of the Norway rat, according to the brain 
weight. This chart is equivalent to, but not directly comparable with chart 2, 
which gives the similar data in the Albino in ratios of the values at birth. 
«——* LWT’, The computed volume of the cerebral cortex, based on table 15. 
------ LWH’, Therelative volume of the entire cerebrum, based on the data 
presented in a former paper (Sugita, ’18) and given also in table 15. XX——XN’, 
The cell density in two unit volumes of the cortex. Graph based on the data 
given as N in column D, table 16. °—-—. eNLWT’, The computed number of 
nerve cells in the entire cortex, based on the figures given in column E, table 16. 
Mark X shows the phase in growth corresponding to that indicated by the same 
mark in chart 2, which shows the end of the second developmental phase in the 
Albino. 
