506 STRUCTURE OF THE [SECT. 2 1 8. 



titions consist for the most part of ordinary fibrous connective 

 tissue, with some few fine elastic elements ; and besides these, 

 there occur a variety of structures very similar to the plasma-cells 

 of Virchoiv ; which I regard as nothing else than young connec- 

 tive tissue. The structures in question are delicate fusiform fibres, 

 whose average length is o'02'", with narrow cell-bodies, which 

 give off fine processes, and contain a small, short, elongated nu- 

 cleus; others of these structures have three of these processes, 

 and they all behave towards alkalies and acetic acid more like 

 connective tissue, and present nothing of the resistance of plasma- 

 cells. These fibrous elements do not lie scattered in the partitions, 

 but rather are grouped into large collections, and they not un- 

 frequently form by themselves the more delicate trabeculse. Not 

 unfrequently, also, on teasing out a washed section of the cortical 

 substance, we may distinctly observe them to be connected by 

 their processes, and they may be cleansed accordingly, as a special 

 modification of what I have termed the 'reticulate connective 

 tissue/ 



The contents of the alveoli of the cortical substance consist of 

 a greyish -white pulp of alkaline reaction, which appears entirely 

 to agree with that of the follicles of the tonsils. In fact, even 

 microscopical examination, as microscopists unanimously assert, 

 detects at first sight nothing but a certain quantity of fluid, with 

 numerous morphological elements. But when this pulp is examined 

 more closely, it is seen to be traversed by a rich capillary network, 

 first indicated by myself (Handb. d. Geiveb., i aufl., 1852, p. 562); 

 so that it comes, indeed, to present an appearance like that 

 pointed out by Ernst, Frei and myself, as characterising the folli- 

 cles of Peyer's glands, or the Malpighian corpuscles of the spleen. 

 I find reason, however, from further study of the lymphatic glands, 

 to agree with Donders, in regarding the composition of the con- 

 tents of these alveoli as quite peculiar. Hitherto we have regarded 

 these alveoli as simple cavities, filled by a connected mass of cells 

 and nuclei, but the true structure would appear to be essentially 

 different from this ; each alveolus proves to be traversed by a 

 very great number of trabecule, mostly very delicate, with fibrils 

 and laminae which anastomose in various wavs with each other, 

 and form a beautiful spongy tissue, which most resembles, of course 

 in miniature, that of the spleen. The microscopical structure of 

 this spongy tissue is extremely beautiful ; and I have observed it 

 nowhere else in the adult. Besides the vessels which are dis- 

 tributed to the alveoli, and which are supported on the larger 



