262 Cc. M. JACKSON 
hematoxylin-eosin stain) of the suprarenal appear similar to 
those normal at three weeks, though certain changes are clearly 
evident (fig. 7). 
The vacuoles in the outer-zone cells usually indicate a progres- 
sive lipoidal differentiation (fig. 7, O). While in a few cases the 
lipoidal vacuoles appear scanty (as normally at three weeks), in 
others the outer lipoid zone was as distinct and clearly differen- 
tiated as normally at ten weeks. In most cases the lipoidal 
content appears somewhere between these two extremes. The 
eosinophile cytoplasmic granules are somewhat indistinct. 
The lipoidal vacuoles of the middle zone were also found in- 
creased in size and number in most cases, though more variably 
and not so definitely as in the outer zone. As in normal differen- 
tiation, the lipoids usually accumulate to a greater extent in the 
outer half of the middle zone. Otherwise there is no constant 
change to be noted, excepting apparently a somewhat greater 
number of degenerating cells than occurs normally. 
The inner zone (fig. 7, 7), however, when compared with the 
normal shows the most conspicuous changes. This zone is con- 
stantly hyperemic and very markedly atrophic. The cells in 
general appear greatly decreased in size, and many show various 
stages of nuclear and cytoplasmic degeneration. More cells are 
flattened at the medullary border than occurs normally. The 
nuclei are frequently pycnotic or karyolytic. Pigment masses 
(not present at three weeks) appear (fig. 7, P) and are even more 
abundant than in the normal gland at ten weeks. 
The medulla (fig. 7, 1) shows relatively less change than any 
other part of the suprarenal. In most cases it resembles closely 
the normal at three weeks, though in some cases there is an evi- 
dent increase in the proportion of smaller, hyperchromatic (oc- 
casionally pycnotic or karyolytic) nuclei. The cytoplasmic gran- 
ules are usually indistinct. No chromaffin tests were made in 
these cases. 
Maintenance from three to fifteen or twenty weeks of age. In 
these two young rats (St 33.1 and St 38.8) held at maintenance 
for unusually long periods, the changes in the suprarenal are 
more pronounced. The glands were fixed in Zenker’s fluid, sec- 
