254 Cc. M. JACKSON 
In a rat at seventeen days (F 7.1) the fresh frozen sections 
of the formalin-hardened gland show the characteristic cor- 
tical opacity due to the liposomes. The clear line between the 
outer and middle zones is distinct. The opacity decreases 
greatly in the inner half of the middle zone and in the inner 
zone, the medulla being perfectly clear. 
This irregular distribution of the liposomes is still more ap- 
parent when the sections are stained with scarlet red or osmic 
acid. The liposomes are most abundant in the outer zone and 
the outer half of the middle zone, where the largest droplets 
now approach nuclear size. Toward the inner cortical zone 
they become fewer and finer. Some of the inner zone cells are 
entirely free from liposomes, others occasionally appear well 
filled. Aside from a few scattered cortical cell islands, no lipo- 
somes appear in the medulla. 
The other supararenal gland from this rat was hardened in 
Miiller’s fluid. The chromaffin reaction of the medulla is more 
definite than in the earlier stages, though not so intense as later. 
All of the medulla parenchyma cells are stained light brown, 
the nucleus darker than the cytoplasm. The vacuoles of va- 
rious size in the medulla cells are unstained, not giving the chro- 
maffin reaction. The blood in the vascular spaces of the medulla 
occasionally presents a reddish-brown color to a variable extent 
(probably from absorbed epinephrin). 
At three weeks. The paraffin sections were stained as usual. 
The outer cortical zone (fig. 6, O) is narrow, usually 6 to 8 (rarely 
12) cells deep. The cells are in irregular masses or columns, 
separated by blood capillaries. Cell boundaries are ill defined. 
The cytoplasm is scanty, contains fine eosinophile granules 
and more numerous lipoidal vacuoles. The nuclei are hyper- 
chromatic, some almost pyenotic. The deepest cells (fig. 6, T) 
are transitional to the middle zone, and form a narrow zone 
nearly free from lipoidal vacuoles. 
The middle cortical zone is broadest. The cells (fig. 6, Mo, 
M71) are arranged in very distinct cell columns, radially arranged, 
and usually but one cell wide. The radial cell columns are 
separated by blood capillaries, which become wider toward the 
