210 CAROLINE M. HOLT 
during this period than the rest of the brain so that at eight 
weeks, for example, the bulbs should form a considerably greater 
percentage of the total brain weight than at thirty days. The 
average absolute weight of the bulbs of the test animals was 
equal to but 70 to 81 per cent of the average weight of the bulbs 
in the control animals of the same series. It is therefore evi- 
dent that the retarding effect of underfeeding has been greater 
upon the olfactory bulbs than upon the other parts of the brain, 
which had 85 to 90 per cent of the weight of the brains in the 
control series. 
If the relative weight of the bulbs in Series A; and A, is de- 
termined for the test group as contrasted with the final control 
group, we obtain the following relations: 
TABLE 1 
PERCENTAGE 
GROUP AGE WEIGHT OF 
OLFACTORY BULBS 
days 
Table 3..........] Test rats, defective diet 60 Beg 
Mails raver cis Final controls 60 3.99 
ab lesa sere i Test rats, defective diet 79 3.39 
MOEN yaeocweee Final controls 79 4.16 
Rablewereter cs... Test rats, defective diet 118 3.83 
Mahler Sw wees Final controls 128 4.30 
This arrangement of the results shows clearly that in each of 
the three sets, grouped according to age, the olfactory bulbs of 
the underfed rats are significantly lighter in proportional weight 
than those of the controls. We may, therefore, conclude that 
the relative weight of the olfactory bulbs is reduced by the 
form of defective feeding employed in this experiment. 
The details are given in tables 2 to 8, which follow. 
8. Series B. Rats on deficient diet from birth 
a. Method. Since it was evident that the earlier the animals 
were weaned, the greater the stunting effect of a qualitatively 
inadequate diet, it occurred to the writer that it would be inter- 
esting to try underfeeding from birth, by underfeeding the 
