BRAIN WEIGHTS OF RATS 559 
BRAIN WEIGHTS IN THE FIRST HYBRID GENERATION RATS (Fi) 
From the correlation table (table 2) the average brain weights 
corresponding to the different body lengths were calculated for F, 
and these are given in chart 1 together with the corresponding 
25 BRAIN WEIGHT T 
GMS 
24 NORWAY 
PARENTS 
e F RE 
23 + & * 
22 
2) o 
= LJ Z) 
2.0. a 
Be : eT a 
LS) 5 + 
al 
18 = * 
WT S @ 
16 Oo 
E | | 
15 25 tf 
14 a I 
cI [oso 
: | | || BODY LENGTH MM 
a - — 
130 140 150 160 110 180 190 200 210 220 230 240 250 260 
Cuart 1 
Showing the computed brain weights in the Norways and Albinos used as 
parents. Also the average brain weights for the F; and F, generations together 
with all the individual brain weights belonging to these hybrid rats. 
Norway rat ee io tat 
O—— © F; hybrid O = Gul a hiyprid: 
@ F; hybrid + F, hybrid 
individual brain weights. It is to be remembered that all the 
rats of this generation are gray in color. We note from the 
chart that with the exception of both ends of the graph where the 
number of observations is small, the average values give a very 
smooth graph and occupy practically intermediate positions 
between the brain weights given by the norway and albino 
parents. Furthermore, from the distribution of individual brain 
