208 CAROLINE M. HOLT 
individuals of Series A is given in tables 1 to 8. The complete 
tables with the records for each individual rat of this, as well as 
of the other series, are deposited at The Wistar Institute. Of the 
two litters weaned at eighteen and twenty days, only three 
individuals survived to be killed; the others died in the cages 
and the brains were not weighed. The records for the three 
rats Just named have been included in tables 3 and 7, and their 
controls, with the corresponding controls. The size and body 
weight of rats weaned at the end of the third week and placed 
on a corn diet indicated clearly that under like conditions, rats 
weaned at three weeks are considerably more sensitive to adverse 
conditions than are those weaned at four weeks. 
For every individual of Series A; and A, (tables 1 to 8), the 
stunting effect of the corn diet was apparent almost from the 
first. During the early weeks of underfeeding the test rats 
appeared rather more lively than the controls. Later this 
activity decreased, the gait became unsteady, and the animals 
appeared stupid. They were often unable to find the dish of 
condensed milk by themselves, whereas control rats would 
go to it immediately. This suggests that the underfed animals 
lacked an acute sense of smell and perhaps did not see clearly. 
In every one of the test animals of which there are complete 
records, the general bodily growth was arrested by a diet of 
corn. This agrees with the observations of Osborne and Men- 
del (13). These rats remained like young animals in appearance 
as well as in size. The earlier weaning took place and the corn 
diet was begun, the more complete the stunting. 
The skeleton became modified and somewhat distorted owing 
to imperfect calcification. The growth of the long bones was 
not quite so completely arrested’as that of the rest of the skele- 
ton. The skull, sternum, and sometimes the ribs, became like 
parchment. In two cases the pressure of the heart upon the 
sternum had formed a sort of pocket out of that structure, which 
appeared like a tumor on the ventral side of the rat. The 
vertebral column became somewhat bowed, giving to the rat a 
‘humped’ appearance and making it necessary to stretch the 
animals when measuring body length. One to four months of 
