11 
been lost in the Zona fasciculata, break up immediately when the Zona 
reticularis is reached and assist in forming its meshwork. While many 
of the fibrils run singly there are, however, irregular fibrillar processes 
which embrace groups of cells in this layer. But as ARNOLD points 
out, the meshwork here is so dense that practically every cell has a 
space in the reticulum for itself. As the fibrils pass from the Zona 
fasciculata into the Zona reticularis they become irregular in direction 
and their subsequent course is so variable and intricate that it is 
difficult to follow them (Figs. 5 and 6, Z. R.). The network of fibrils 
in the Zona reticularis forms a sharp line of demarcation between the 
cortex and medulla and where there are invaginations of the cortex 
into the medulla the junction between the two tissues is still separated 
by this thick network. 
In the dog the line of demarcation between the cortex and me- 
dulla is fairly regular, although it is not uncommon to find either 
projections of the medulla into the cortex or invaginations of the 
cortex into the medulla, but in these instances the definition of the 
two {tissues is still sharp inasmuch as the dense framework of the 
cortex is easily distinguished from the loose septa of the medulla. 
From the Zona glomerulosa strands of reticulum run into the medulla 
and unite to form irregular spaces which contain the groups of medul- 
lary cells (Figs. 7 and 8, m). These spaces are not subdivided by a 
fine reticulum although in preparations made by Marr’s method dis- 
placed fibrils are frequently seen stretching across them. They are, 
Fig. 7. Fig. 8. 
Figs, 7 and 8. Reticulum from the medulla. Fig. 7, by SPALTEHOLZ’ method 
Fig. 8, by MALL’s method. Magnified about 120 diameters. 
m space for the groups of cells of the medulla. » vein. e horizontal section of 
septum, 
