DR. H. WATNEY ON THE MINUTE ANATOMY OF THE THYMUS. 
1 103 
and that the cortical part of the follicle is composed of lymphoid cells and retiform 
tissue. 
The so-called Hibernating Glands. 
The situation of these glands has been well-described by Barkow (21). He divides 
them into four : cervical, thoracic, axillary, and dorsal. Their structure is somewhat 
foreign to our present purpose of describing the thymus; as these glands only occur, 
to any extent, in a few animals, most of which hibernate. It was, however, necessary 
to examine them, as there has been so much confusion between hibernating glands and 
thymus. 
They are well seen in the Hedgehog, and we have also examined them in the Alpine 
Marmot and in the Bat, and have found microscopical traces of them in the Cat. The 
hibernating gland in the last animal appears to have been seen by Bemak (57), as he 
says that at the upper end of the thymus of newly-born Kittens there is a small 
yellow gland, which consists of granular yellow cells (like liver cells) lying close 
together. 
As seen by the naked eye, or by low powers, the shape of the lobules, in the hiber¬ 
nating gland and in the thymus, is identical; but the situation and the colour of the 
glands are so different, that at once the eye can distinguish between them ; the one 
being of a red-brown, and the other of a pale grey colour. Their microscopical appear¬ 
ances are very different. The glands are composed of granular polygonal cells, placed 
close to one another, often arranged in rows, and having narrow capillaries between 
the cells. In their minute anatomy these glands rather resemble the liver, than any 
lymphoid tissue.* 
Haemoglobin contained in Cysts and in Colourless Cells. 
In the thymus of all animals, haemoglobin is found, either contained within cysts 
(the cysts, as we have noticed before, arise from the concentric corpuscles), or in cells; 
these cells appear to be always situated near to the concentric corpuscles, and often 
form part of them. 
The cysts in the Hog, Bird, and Tortoise are, when small, filled with degenerated cells, 
and when large with haemoglobin masses and granules (see pages 1093, 1098, 1099). 
* In the Rat, the thymus is contiguous to the hibernating gland, which in its turn runs up to the 
salivary glands. 
In the Hedgehog, there are present in the thorax the thymus, a lymphatic gland, and the hibernating 
gland, in contiguity to one another. The hibernating gland has two kinds of alveoli, one composed of 
spindle-shaped cells, and the other of polygonal cells, which have been described above. 
The thymus of the Rat and of the Hedgehog, therefore, present unusual difficulties; and conclusions 
drawn from them are not of great weight, unless shown to be in accordance with the structure of the gland 
in other animals. 
7 B 
MDCCCLXXXTI. 
