146 
W. F. R. WELDON. 
selves to the epithelium of the glomeruli, so as to appear as in 
fig. 18. In this figure the epithelium of the glomerulus is seen 
to be distinct from the suprarenal for a short distance ; but in 
a part of the section I was unable, after a tolerably careful 
examination, to convince myself of the existence of any distinct 
layer of epithelial cells separating the cavity of the glomerulus 
from the adjacent blastema. 
Such a section as that shown in fig. 18 may be seen in almost 
any glomerulus in the region of the suprarenal during the 
seventh day. On the eighth day the appearance of the blas- 
tema changes. While still retaining its connection with the 
glomeruli (fig. 19) it has increased considerably in size, and its 
component cells have acquired most of the histological charac- 
ters which they present in the adult. The individual cells are 
large, polygonal, and distinctly marked off one from the other ; 
their protoplasm, which does not stain very readily with car- 
mine or hsematoxylin, is clear or very finely granular, and their 
nuclei are clear, oval, or elliptical, with well-defined contours 
and a number of coarse granules in their interior. The most 
characteristic feature in the blastema of this age is, however, 
the definite arrangement of the cells into columns, giving them, 
more than at any earlier stage, the appearance of the cortical 
substance of an adult suprarenal. 
I have already said that the blastema during the eighth day 
remains attached to the glomeruli ; such appearances as those 
seen at x in fig. 19, which are very frequent, tempt one 
strongly to believe that at tbis time the number of the cells 
composing it may be added to by proliferation from the glome- 
rulus epithelium ; but I have not been able to satisfy myself 
that this is the case. 
From this time the changes in the cortical blastema, so far 
as I have followed them, do not differ in any important parti- 
culars from those described by Braun in Lacerta muralis. 
A noticeable feature throughout the whole of the early 
history of the organ under consideration in the chick, is the 
very distinct separation between the cortical blastema and the 
blood-vessels, the original blastema-cells being at a great 
