39 8 GLAND-GRANULES OF THE THYMUS. [sect. 1 82. 



category as the wall of the follicles of the Peyerian patches, of the 

 tonsils, etc. "Within this envelope, between it and the cavity of 

 the lobule, there is situated a greyish-white, soft, delicate substance, 

 ■£•'" to ±'" in thickness, which, examined microscopically, appears to 

 consist of nothing but free nuclei and small cells, and hence has 

 hitherto been unanimously regarded by all observers as the secre- 

 tion of the supposed gland-vesicles. This substance, however, 

 cannot be washed off, as would be the case if it lay loosely in the 

 space surrounded by the delicate envelope, but, rather, it presents 

 a considerable degree of toughness and resistance. If it be more 

 narrowly investigated, it is gradually perceived that other elements 

 besides these, in part of quite an unexpected kind, enter into its 

 composition; these are blood-vessels, and a small quantity of a 

 fibrous substance like connective tissue, so that we are here pre- 

 sented with a structure not dissimilar from that of the contents 

 of the Peyerian follicles. 



"With regard to the structure of the walls of the lobules, the 

 chief mass is composed of the foregoing pseudo-vesicular elements, 

 together with a small quantity of fluid connecting them. The 

 constituents of these are, first, round or flattish nuclei,' measuring 

 0*002'" to o'oo5'", with clear, homogeneous contents, and with 

 or without nucleoli; these nuclei are always met with in large 

 numbers; by the addition of caustic soda, or acetic acid, their 

 contents become granular and turbid. Secondly, cells are found ; 

 and I believe with Ecker and Jendrassik^ in opposition to Simon, 

 that these are never absent. They are of very various sizes 

 (o'oo^" to o'oi'"), and although the}? - vary in number, still they 

 are always much more scanty than the nuclei. Their nuclei are 

 generally simple and distinct, and their contents are either pale or 

 are composed of scattered fat-granules, or else the cells are destitute 

 of a nucleus, and entirely filled with fat. This last condition 

 Ecker states he has observed after the complete formation of the 

 organ. Through the midst of these elements there run a great 

 number of larger and smaller blood-vessels. The main vessels 

 running external to, but close upon the central cavity in the longi- 

 tudinal direction of the organ, give off branches especially to the 

 central cavity, which penetrate its walls, and arrive at its inner 

 surface. Here they ramify and anastomose, and form a moderately 

 dense network of capillaries, which are contained in a delicate mem- 

 brane of connective tissue. From this arterial network numerous 

 vessels are distributed to the substance of the lobule, especially 

 from the point where its cavity joins the main canal ; and these 



