GROWTH OF THE GEREBRAL CORTEX 179 
3. What will be the relation between body weight and brain 
weight in the underfed rats? 
4. How far will the size and shape of the cerebrum be in- 
fluenced? 
5. Will the thickness of the cortex of the stunted rats be 
different from that of the standard? 
6. How far will the Volume of the cerebral cortex be modified? 
7. Will the number of the cortical cells increase normally 
according to age? 
8. Will the development in the size of the nerve cells be influ- 
enced by starvation? 
9. What will be the effect of the starvation on the percentage 
of water and on the alcohol extractives? 
2. THE TEST ANIMALS 
After several preliminary tests on producing underfed young, I 
adopted the following three procedures, which are fairly reliable: 
I, Separation of the young from the nursing mother for a 
maximum period each day. 
II. Entrusting one mother with an excessive number of young 
and thus reducing the amount of milk available for each of the 
young. 
III. Underfeeding the nursing mother and thus reducing the 
quantity of milk secreted. 
I treated five litters by the first method (Series I),-two litters 
by the second method (Series IT), and one litter by the third 
method (Series III). The detailed records of these experiments 
are on file at The Wistar Institute of Anatomy and Biology. 
All the material, consisting of forty-six test individuals and four- 
teen controls, from the above eight litters, was supplied from the 
rat colony at The Wistar Institute. They are all from mothers of 
standard size which were kept throughout the experiment under 
good sanitary conditions. 
This study was carried on from October, 1916 to July, 1917, at 
The Wistar Institute of Anatomy and Biology. 
