588 
MR. E. C. BABER OR THE STRUCTURE OF THE THYROID GLARE. 
in a surface view. In a profile view of the epithelium of the Tortoise (hardened in 
alcohol) there are seen at intervals amongst the epithelial cells, narrower cells with 
much elongated nuclei, which latter take the hsematoxylin stain more darkly than the 
nuclei of the epithelial cells. On examining these cells carefully they are found to be 
expanded somewhat like a fan at their summits, and also sometimes at the base, although 
the latter is not always the case. Probably these are more or less branched cells, which 
are situated in the swollen parts of the reticulum above-mentioned. The reticulum as 
well as tire club-shaped cells just described are very plainly seen in the thyroid glands 
of the Conger Eel and Skate. Plate 68, fig. 6, gives a surface view of the epithelium as 
seen in a section of the thyroid of the Conger Eel, hardened in spirit. Amongst the 
epithelial cells in this figure are seen the branched or stellate nuclei of the club-shaped 
cells. In this animal, as well as in the Skate, the club-shaped cells are often seen in 
great numbers in a profile view of the epithelium. It is a common thing to see two 
of these cells in close approximation to each other, almost suggesting the appearance 
of stomata opening into the cavity of the vesicle. That these cells however bear an 
important part in the absorption from, or secretion into, the cavity of the vesicle is, I 
think, probable, although I am unable to speak more definitely on this point. In the. 
Conger Eel the expanded summits of the club-shaped cells may often be observed 
projecting slightly beyond the surface of the epithelial layer. 
The reticulum is also seen in the thyroid gland of Mammals, such as the Sheep and 
Kitten. 
Basement membrane. —In a double-injected gland of the Tortoise in which the blood¬ 
vessels were injected with carmine-gelatine and the lymphatics with Berlin-blue 
solution, I have found that the arteries are surrounded more or less completely by 
their accompanying lymphatics ; the capillaries, on the contrary, run between the 
epithelium of the vesicles and the smallest ramifications of the lymphatics, which in 
this animal are found between almost all individual vesicles. This relation of the 
lymphatics to the capillaries and arteries can be easily seen in uninjected sections of 
the same gland, also in those in which the lymphatics only are injected by the 
puncture-method. Plate 68, fig. 9, exhibits this relation of the minute lymphatics to 
the capillaries in the thyroid of the Tortoise. It represents a transverse section of the 
walls of two adjacent vesicles with the inter vesicular structures. 2 , 2 are the cavities of 
the two vesicles, 1 , 1 their epithelial walls. In the centre is seen the small lymphatic 
(3, 3), and between this and the epithelium on each side the capillaries (4, 4, 4). 
As the ramifications of the capillaries are much more minute than those of the 
lymphatics, spaces are frequently left between the capillaries in which the endothelial 
wall of the lymphatic is not separated from the epithelium by a blood-vessel, and at 
these points the epithelial cells appear usually somewhat elongated. Two of such 
points are seen in the figure (Plate 68, fig. 9). In osmic acid preparations of the 
Tortoise, where the wall of a vesicle happens to be cut obliquely, lying outside the 
epithelium, is seen the nucleated membrane formed by the endothelial cells of the 
