WEIGHTS OF UNDERFED YOUNG ALBINO RATS 341 
found the kidneys to lose weight relatively slightly less than the 
entire body. 
TESTES AND EPIDIDYMIDES 
From the data in table 2 it can be seen that the Wistar data for 
the testes greatly exceed the corresponding weights for my control 
rats at 7 and 13 days of age. At one week the difference (0.016 
to 0.041 gram) is especially striking. However the combined 
average weight of the testes and epididymides (0.0238 g.) for my 
controls at one week corresponds closely with Jackson’s (13) 
normal (0.0273 g.) at the same age. It is therefore apparent that 
the Wistar data are much too high for these young rats. For the 
older controls, my data correspond fairly well with the Wistar 
tables. 
Using my controls for comparison the weight of the testes in the 
test rats is exceedingly high at three, six and ten weeks of age. 
At three weeks the weight of the testes in the test rats exceeds that 
for the younger controls of the same body weight approximately 
188 per cent. At six and ten weeks of age the increase (uncor- 
rected for differences in body weight) amounts to about 62 and 51 
per cent respectively, having become progressively less. 
In the rats weighing 75 grams at 291 days the weight of the 
testes is practically identical with that for the controls. At 139 
and 412 days of age, however, the testes have evidently suffered a 
marked loss in weight. The decrease (0.394 gram to 0.228 gram) 
in the test males of the latter group amounts to a loss of about 42 
per cent. 
From the foregoing it is evident that in young rats the testes 
increase considerably during the shorter periods of underfeeding. 
With very prolonged stunting, however, the testes may show 
practically no change, or a loss which varies up to a considerable 
amount. Jackson (’15a) noted an increase of 34 per cent in the 
weight of the testes in young rats held at constant body weight 
from three to ten weeks of age. My results are much more strik- 
ing, however, which is probably due to the stronger growth tend- 
ency of the testes in my very young rats which were underfed 
from birth. Considerable caution must be exercised in drawing 
