‘ WEIGHTS OF UNDERFED YOUNG ALBINO RATS 343 
In my rats underfed from birth to three, six and ten weeks of 
age, there is apparently a considerable increase in the weight of 
the ovary. At ten weeks the increase from an average of 0.0028 
gram in the controls to 0.00438 gram in the test rats represents a 
gain of approximately 54 per cent (uncorrected for body weight). 
At three and six weeks of age the differences are greater, amount- 
ing to 83 and 91 per cent respectively. 
The data for the ovaries in the females subjected to very long 
periods of fasting are variable, but in most instances show a 
tendency to increase. Conclusions, however, are hazardous on 
account of the small number of observations and also on account 
of the extremely great cyclic changes in the weight of the ovary 
due to ovulation. Also the normal growth curve of the ovary is 
very complicated, as shown by Hatai (13). 
Jackson (15 b) observed in the ovaries a decrease of about 27 
per cent in weight in young rats kept at constant body weight 
from three to ten weeks of age. His data, however, indicate a 
slight increase in the youngest group underfed from three to six 
weeks. My results would indicate that at earlier periods the 
growth impulse of the ovary in underfed rats is still stronger, 
resulting in a marked increase in its weight. 
HYPOPHYSIS 
The weight of the hypophysis (table 2) appears higher in my 
controls (except for the one female weighing about 70 grams) than 
the Wistar norm for rats of corresponding body length. The high 
weight for the gland in my controls can be attributed partly to 
differences in body weight, my rats being slightly heavier than 
the norm for corresponding body length. 
As compared with my controls, the weight of the hypophysis at 
three, six and ten weeks of age is higher in the test rats than in the 
controls. At three and ten weeks of age the increase (sexes com- 
bined) for the test rats amounts.to approximately 33 and 24 per 
cent respectively (uncorrected for slight difference in body 
weight). At six weeks of age the increase is less, amounting to 
about 8 per cent. There is apparently no sexual difference in the 
increase at these ages. 
