DR. H. WATNEY ON THE MINUTE ANATOMY OP THE THYMUS. 
1071 
are wide lymphatic spaces which invest the follicles; these communicate, by means of 
finer vessels, with the central part of the follicle. He gave the last blow to the idea 
that there are cavities in the thymus, and he, found the individual follicles either 
entirely encapsulated or at times united. He described three kinds of networks in 
the gland : one, composed of anastomosing cells; a second, a narrow network with 
greater breadth of trabeculae ; and a third, formed of strong elongated fibres stretched 
between adjoining vessels. The cells enclosed in the network are small cells, similar 
to lymphatic corpuscles, large coarsely granular spheroidal bodies with one or more 
nuclei, and concentric corpuscles. 
Fleisch (64), 1870, in writing about the thymus of Amphibia, described and figured 
so-called ganglion cells; these were the granular cells already described by Kolliker 
(54), and Paulizky (49), and figured by the latter. 
Henle (65), 1873, described the thymus, and appeared rather to lean to the older 
view, that the follicles contain cavities. 
Cornel and Banvier (50), 1873, said that concentric bodies, calcified or otherwise, 
are often found in the thymus; these bodies hang from the vascular walls, and have 
the same origin as the angiolithic sarcoma— i.e., they arise as hollow buds, which 
communicate with the lumen of the vessel, and growing, become pedunculated. The 
cellular elements are flattened, and arranged in concentric layers upon the wall of the 
vessel. 
Bainey (66), 1875, put forward some peculiar views as to the physiology of the 
thymus. 
Krause (67), 1876, described long spaces as existing in the gland, connected with 
one another : they are not canals, but connective-tissue spaces, filled by arteries, veins, 
lymphatic vessels, and nerves. The follicles are completely penetrated by blood vessels. 
The external vessels are radiating. 
Afanassiew (51), 1877, said that the concentric corpuscles arise from the endo¬ 
thelium of the veins and capillaries; the endothelial cells increase by division, and fill 
the lumen. He found vessels in which the lumen was stopped up by the increase, 
and others where the endothelium was concentrically arranged. He noticed blood coi- 
puscles in the interior of the concentric corpuscles ; and also said that the walls of the 
vessels are often thickened, and can beget the capsule-like formations. He ‘quoted 
the monograph on the development of cancer by Koster, who said that concentric 
corpuscles in carcinoma are derived from the endothelium of the lymphatic vessels. 
In a second paper, Afanassiew (33) found that the periphery of the follicles is 
clearly bordered, and that the central parts run into one another. In describing the 
network, he said that it is not formed of cells, except in the embryo; but that flat 
connective-tissue cells lie on the nodal points of a reticulum. There are lymphatic 
vessels in the interfollicular tissue, and they spread out into the follicle, in the direction 
of the blood vessels. The lymphatic vessels, leaving the thymus, run to lymphatic 
glands in the mediastinum and in the neck. He found that coloured and colourless 
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MDCCCLXXXIT. 
