8 NAOKI SUGITA 
W.B x L.G X Ht., based on the measurements given in table 
2. Table 3B gives the similar calculations for the Albino cere- 
brum based on the measurements given in table 3 of the first 
paper in this series (Sugita, 717). 
Table 4 gives for both the rats the cerebral volumes (A) ac- 
cording to brain weight, and (B) according to age. In table 4 A, 
TABLE 4 
Giving the ratios of the cerebral volumes of the Norway to the Albino rats (A) pairing 
the brains of the same weight and (B) pairing the brains of thesameage. Calcu- 
lated on the basis of the data given in table 3 
(a) (B) 
Pairs of groups in w hich acom- | Ratio of cerebral || Pairs of groups in which a com-| Ratio of cerebral 
parison of cerebral volume was | volume between| parison of cerebral volume was | yolume between 
made. Like brain weights two groups of the) made. Like ages two groups of 
like weight. the like age. 
Norway Albino Albino = 1.000 Norway Albino Albino = 1.000 
N XI xa 1.016 N XI IX 1.159 
N XIII XIII 1.097 N XIII X! 1.271! 
N XIV XIV 1.031 | N XIV XI e212 
N XV XV 0.994 li Ni XV) exalall _1.210 
N XVI XVI 1 O13 ee yy Nel Ui 1227 
N XVII XVII IONS | N XVII XIV 1.224 
N XVIII XVIII 1.019 N XVIII XV 1.161 
N XIX XIX 1.053 N XIX 
N XX xX 0.951 N XX XVI 1.212 
N XxXI XVII 122i 
N XXII XVIII 1.248 
le IN) Sexe sT | Sxaox: 1.210 
IAVET AGC. ska cee ae 1.021 ly) Avena erence eo i 1.214 
1 As the reduced brain weight of Group N XIII falls between the brain weights 
of Groups X and XI, the mean value @ the cerebral volumes of Groups X and XI 
was used in comparison. 
the brains of like brain weight groups are compared, by pairing 
the groups which carry the same number. By this comparison, 
it is seen that, on the average, the values for the Norway rat 
are somewhat greater, except in Group XV and in the old age 
group, Group XX, in which the reverse is true This shows that 
the Norway brain has, as a rule, a less specific gravity than the 
brain of the albino which has the same weight. One important 
