560 
ME. E. C. BABEE ON THE MINUTE ANATOMY 
have observed it in specimens prepared by the above-mentioned methods, in order to 
render the descriptions that are about to follow intelligible. 
First, with regard to the stroma. In the dog, as above mentioned, the thyroid gland 
consists of two separate portions. Each of these forms apparently a single lobe, which 
is divided into lobules, more or less distinctly, by processes of connective tissue passing 
inwards from the surface of the organ, where they are continuous with the connective- 
tissue capsule surrounding the gland. These bands of connective tissue run chiefly 
with the blood-vessels, and gradually diminish in size, till between the individual 
vesicles it is often impossible to say that there is any stroma present. On the whole 
the connective-tissue stroma appears very sparing in quantity in the thyroid gland of 
the dog. 
The Vesicles . — Between the different ramifications of the stroma are seen the vesicles 
with their walls, consisting of a single layer of cells arranged like an epithelium, and 
usually known as “ epithelial cells.” These commonly present a square or wedge-shaped 
outline, though their shape varies in different preparations and in different parts of the 
same specimen. They are usually higher than broad (Plate 48. figs. 8, 13); sometimes, 
however, they present a more or less flattened appearance, probably the effect of the 
reagents (Plate 47. fig. 1). Under certain circumstances these cells present a more or 
less triangular outline, of which more hereafter. Their cell-substance is finely granular, 
and they are each provided with a single spheroidal nucleus. With regard to the 
existence or not of a membrana propria outside the epithelial cells, I am not in a position 
to make any definite statement. I may, however, draw attention to the following 
appearance which I have noticed once or twice in these preparations. In a vesicle 
where the epithelial cells are partly deficient a distinctly marked line, which occupies 
the curved inner aspect of the epithelial layer, is directly continued onwards in the same 
direction, for a distance of at least two or three cells, beyond the point where the cells 
cease to be present. This gives an appearance as if there were a distinct membrane 
lining the inner aspect (or summits) of the epithelial cells, those that are deficient 
seeming to have become separated from it. This appearance, however, is probably 
produced by a layer of hardened secretion adhering to the cells. As mentioned by 
Verson (op. cit. p. 371), in the dog the walls of the vesicles are frequently seen to be . 
inflexed, forming projections into the cavities of the vesicles. 
Contents of the Vesicles . — The contents of the vesicles consist, in addition to a small 
quantity of a pellucid substance sometimes present, of a peculiar material which shrinks 
away from the walls of the vesicle and forms a solid mass in the centre. In sections 
stained with picrocarminate of ammonia it appears as a finely granular substance of a 
more or less bright yellow hue, contrasting with the red colour of the walls of the 
vesicles. In specimens coloured with heematoxylin, on the other hand, it presents the 
appearance of an opaque, grey, or greyish- violet mass, which is generally uniform, but 
sometimes finely granular, in appearance. 
From a careful examination of sections of the thyroid gland prepared by the above 
