236 Cc. M. JACKSON 
2. In young rats stunted by underfeeding 
Table 4 includes the individual results in four young rats held 
at maintenance from three weeks to ten or twelve weeks, and 
one in which the experiment continued to 139 days. Since in the 
latter case the cells and nuclei are similar in size to those of the 
other cases, the average is also given for the entire group. In the 
following discussion the data are compared with those of normal 
rats at the same body weight (that is, at three weeks, when the 
experiment began). 
The cells of the outer zone have in some cases apparently in- 
creased in average diameter, but the average for the group is but 
slightly increased, if at all. The cells of the outer part of the middle 
zone show an increased average diameter in all cases, the average 
for the group being 11.1 uw. This is greater than the normal at 
three weeks (9.7 «), though less than the normal at ten weeks 
(14.5 wu). The cells of the inner part of the middle zone, on the 
contrary, shows a definite decrease to 8.9 u (from normal 10.5 1). 
The inner-zone cells likewise decrease in average diameter to 8.1 yu 
(from 9.5 uw), but the cells of the medulla show but little if any 
change in size. 
In nuclear size the outer zone in the suprarenal cortex of the 
maintenance rats is but slightly changed. The average nuclear 
diameter is slightly lowered, with a corresponding decrease in the 
relative volume of the nucleus to 25.7 per cent (from normal 34.5 
per cent). The nuclei in the outer part of the middle zone re- 
main nearly unchanged in average diameter, but on account of 
the increase in cytoplasm and cell volume the relative size of the 
nucleus decreases to about 17 per cent (from normal 27 per cent) 
of the cell volume. The nuclei in the inner part of the middle 
zone show a definite decrease in diameter to 5.5 uw (from normal 
6.2 uw), but as the reduction in cell diameter (cytoplasm) is still 
greater, the relative volume of the nucleus averages slightly 
higher at 23 per cent of the cell volume (normal 21 per cent). 
The inner cortical zone nuclei decrease in average diameter to 
4.9 uw (from 5.7 uw), but since the cytoplasm decreases similarly, 
the relative volume of the nucleus is unchanged. The nuclei 
