GROWTH OF THE CEREBRAL CORTEX a3 
TABLE 9 
Giving the percentage of water in the brain of the Norway and of the albino rats of the 
same age. The comparison of the data of the two forms is made so as to bring those 
of approximately the same age on the same line of the table. Based principally on 
tables 10 and 12, given by Donaldson and’ Hatai (711) on pp. 439-443, Jour. of 
Comp. Neur., vol. 21 
NORWAY RAT (MALES) ALBINO’ RAT (MALES) OF LIKE AGE 
PERCENTAGE OF WATER : LESS THAN 
AGE Wana Setar ee sae arcane oe 
OBSERVED eer eae Sateanese CALCULATED|CALCULATED] aap 
days grams grams per cent per cent grams grams per cent 
i 5.1 0.2361 88 .2 88.00 4.7 0.217 8 
10 12.2 0.859 86.9 87.05 TRS 0.840 2 
13 18.1 1.245 85.3 85.39 14.9 1.011 19 
15 - tate 1.195 84.5 84.58 16.1 1-057 12 
16 26.1 1.368 82.8 84.19 16.7 TOC 21 
19 25.5 1.423 81.5 83.12 18.7 1.131 21 
25 32.6 1.498 80.9 81.39 23.9 1.237 17 
40 35.88 1.525 79.2 4 79.39 42.5 1.434 6 
47 38.5% | 1.522 79.3 79.24 54.1 1.507 1 
106 68 .68 1.878 78.4 78.50 174.0 1.830 3 
200.0 2.152 78.7 78.59 160.0: 1.807 16 
215.0 PARC 78.8 78 .53 170.0 1.824 16 
231.0 2.20 78.6 78.45 180.0 1.8388 16 
248 .0 2.23 78.7 78.38 190.0 1.854 17 
267 .0 2.25 78.2 78.32 200.0 1.866 ilf/ 
287.0 2.28 78.2 78.24 210.0 1.879 18 
308 .0 2.31 78.9 78.18 220.0 1.890 18 
331.0 2.33 78.2 78.12 230.0 1.903 18 
355.0 2.35 78.3 78.11 240.0 1.913 19 
380.0 2.38 78.2 78.10 250.0 1.923 19 
406.0 2.41 78.0 78.06 260.0 1.933 19 
434.0 2.43 78.2 77.96 270.0 1.944 20 
463.0 77.9 77.50 280.0 1.954 
494.0 78.0 290.0 
525.0 78.0 300.0 
1 The data given in this column below this entry are based on unpublished ob- 
servations of Donaldson and Hatai, the records of which are kept in the Wistar 
Institute. 
* The data given in this column below this entry were obtained by calculation 
according to body weight. 
3 As the result of confinement, the body growth in the Norway is remarkably 
retarded. 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 29, No. 1 
