OF THE THYROID GLAND OF THE DOG. 
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membrane, which in some places is cut away, is seen investing the outer 
surface of the vesicles. The structure of the vesicles is not represented, their 
outlines being indicated by the shading. (Obj. 3, oc. III.) 
Fig. 7. From a longitudinal section of the gland injected with silver, showing the wall 
of a lymphatic vessel. The endothelial cells are seen with their oval-shaped 
nuclei faintly stained with hsematoxylin. Some of the cells have two, others 
three nuclei. Some of the nuclei are seen crossed by the silver lines. 
(Obj. 3, oc. I.) 
Figs. 8 to 15 illustrate the appearances presented by the “parenchymatous” cells of 
the thyroid gland. They are all taken from sections of the gland hardened in alcohol 
and stained with haematoxylin. All except fig. 11 are drawn with obj. 8, oc. I. 
In figs. 8, 10, 11, 12, 13, 14 and 15, a indicates the interior of a vesicle, and b the 
parenchymatous cells. 
Fig. 8. From a transverse section, representing a small portion of the wall of a vesicle (a) 
with its layer of epithelial cells. A large round parenchymatous cell ( b ) 
is seen, which has so flattened out two epithelial cells that it has formed 
on their outer aspect a cup, in which it lies. 
Fig. 9. From a longitudinal section, showing several parenchymatous cells (with their 
cell-substance not shrunk) situate at various distances from the interior of 
the vesicles ( a a). Some are separated from the cavity of the vesicle by 
merely a membrane (<?), others by flattened epithelial cells, and others, again, 
by normal epithelial cells. Between a and a a cavity is seen left between 
the epithelial cells, out of which a parenchymatous cell has probably escaped. 
Fig. 10. From a transverse section. Three parenchymatous cells [b) with their nuclei 
are seen apparently situate in a common cavity, and not encroaching, as far 
as can be seen, on the wall of a vesicle. Their cell-substance appears shrunk. 
Fig. 11. From a transverse section, showing a similar space containing apparently two 
parenchymatous cells ($), one of which presents the appearance of hanging 
into the space and of being attached to the epithelial cells. (Drawn with 
obj. ^8, oc. III.) 
Fig. 12. From a transverse section. A portion of the epithelial wall (a) of a vesicle is 
seen in which are two parenchymatous cells ( b , c). The one ( c ) with its cell- 
substance not shrunk is apparently still separated from the cavity of the 
vesicle by a membrane ; the other ( b ) exhibits a shrunken cell-substance, 
which, together with its nucleus, stands in free communication with the cavity 
of the vesicle ( a ). 
Fig. 13. From a longitudinal section of the gland, showing a portion of the walls of 
three contiguous vesicles ( a a a). In the wall of one is seen a parenchymatous 
cell ( b ), with its cell-substance slightly shrunk, which, owing to the flattened 
epithelial cells surrounding it having separated, stands in direct communica- 
tion with the interior of the vesicle (a). This figure shows well the walls of 
