320 CHI PING 
To return to table 3, the ratios between the cell and nucleus 
tend to increase up to the age of twenty-five days; from that 
time on the ratio in every case is almost 1:1.9. It should be 
noticed, moreover, that there is during this later period no in- 
crease in the ratios as the animal increases in age or in size. 
This fact will be discussed later on. 
TABLE 5 
Giving according to percentage of water in the brain the computed diameters of the 
cells and nuclei in the superior cervical ganglion of the Norway rat. Sexes sep- 
arated. Data condensed 
MALE FEMALE 
‘ P eS 
Mean | Number Daan aes Computed Computed : ae Number |: Mean 
pia | Soe ee |, aiemeter | attri | on | oe 
age le average Nucleus Cell Cell Nucleus meee ced tics 
iu Lu iD M 
100 1 80.4 13.4 26.0 Qa40 ii 80.4 2 68 
54 2 79.5 Ze 24.2 DRY Fi 12.6 79.6 5 46 
153 5 COG See 28.4 \ 26.6 13.0 (820 4 129 
172 5 78.3 13533 28.2 Pai 574 S351 78.5 5 164 
258 i 78.1 14.1 32.4 29.5 3355 18.2 5 203 
194 2, Holl 13.0 28.9 30.2 1320 Was ay 205 
253 3 774 14.1 31.4 26.6 PA} 77.4 -2 175 
3381 i 76.8 leo 30.8 28.2 12.8 77.0 5 203 
D. In relation to the percentage of water in the brain as an 
indication of age « 
Accepting the conclusion (Donaldson, ’10) that the percentage 
of water in the central nervous system is more closely correlated 
with age than with body weight and brain weight, it was thought 
worth while to study the growth of these cells in relation to the 
percentage of water in the brain, in order to supplement what 
has been presented in the preceding paragraph, based on ani- 
mals of known ages. | 
Table 5 is, therefore, to a certain extent, a continuation of 
table 3. For each sex there are eight entries based on the con- 
densed data, those cases with known ages being excluded. ‘The 
corresponding graphs appear in chart 4. According to Don- 
