OLFACTORY BULBS OF THE ALBINO RAT 207 
With the rats weaned at three weeks or in case of small rats 
from very large litters, there was a good deal of trouble in keep- 
ing the animals on the corn diet for so long a time, and of course 
the difficulty increased as the period of underfeeding was 
prolonged. ) 
At first an attempt was made to keep animals from several 
litters in one cage with the result that after a short time, the 
less well grown rats were killed and eaten by the stronger indi- 
viduals. Then the plan was adopted of having members of 
only one litter in a cage. This worked successfully up to the 
time when the animals began to weaken. Then the males 
frequently killed and ate the females. So finally, for prolonged 
experiments, it was found safer to place only animals of the same 
sex, approximate weight and physical condition together, but 
even this precaution was not always sufficient. 
In most cases, for the first few weeks, there was a very slow 
gain in weight or the weight was just maintained. But in every 
case when an animal began to lose or became very feeble, a 
dose of condensed milk was fed. One or two doses were usually 
sufficient to restore the animal to equilibrium and there was not 
infrequently a sudden temporary gain in weight, doubtless due 
to increased appetite and the consequent gorging of the ali- 
mentary tract with corn. 
In a few cases where the underfeeding had gone on for several 
months, it became necessary to administer small doses of con- 
densed milk more frequently—in two cases, practically every 
day—in order to keep the animals from losing weight. 
At the end of the experiment, both test and final control ani- 
mals were killed, weighed, measured, eviscerated, and brains 
and bulbs weighed as in the case of the initial controls. One 
bulb with a part of the cerebrum was preserved for histological 
study. A record was kept of any signs of disease or other 
abnormality. The weighing was done in closed bottles and all 
weights of brain and of olfactory bulbs were made to 0.1 mgm., 
but recorded here in milligrams only. 
b. Results. General morphological and physiological modi- 
fications. A summary of the data from observations upon 108 
