358 



THE LYMPHATIC SYSTEM. 



multitude of smaller spaces by the inosculations of this fibrous frame- 

 work. The bands constituting this framework are called the " trabeculse." 

 Secondly, in the interstices between the trabeculse there is situated the 

 pulpy substance of the gland. In the more external or cortical part of 

 the gland, the interspaces have a rounded or sac-like form, which gives 

 to this portion of the organ a granular aspect, while this appearance is 

 wanting in the deeper or medullary portion ; but in both situations the 

 glandular pulp has essentially the same microscopic texture. Thirdly, 

 the bloodvessels of the gland penetrate it from the outside, usually at a 

 depressed spot called the "hilum," and, after reaching the interior, break 

 up into a rich plexus of capillaries. These bloodvessels and their capil- 

 lary plexus follow distinct routes in the gland, in the middle of the 

 spaces between the trabeculse. The capillary bloodvessels are sur- 

 rounded and held in position by very fine branching fibres attached to 

 their external surface; and in the meshes of these fibres, as well as 

 between the bloodvessels, there are imbedded a great number of rounded, 

 granular, nucleated cells, about 9 mmm. in diameter, similar to the white 

 globules of the blood and of the lymph, and which in this situation 

 are known as "lymph globules." The presence of these granular cells, 

 fixed between and immediately around the capillary bloodvessels, gives 

 to the parts occupied by them a well-marked opaque appearance by 

 transmitted light ; and there are thus formed, in a thin section of the 

 gland, elongated, opaque tracts or cords, separated by intervening trans- 

 parent spaces, and communicating with each other at frequent intervals. 



Fig. 127. 



Fig. 128. 



THIN SECTION OP A LYMPHATIC GLAND 

 FROM THE Ox. o. Medullary cords, b. Lymph 

 paths, c. Trabeculae. (Kolliker.) 



LONGITUDINAL SECTION through 

 the hilum of a mesenteric gland from 

 the ox, showing the commencement of 

 the efferent lymphatic vessels injected 

 from a puncture of the glandular sub- 

 stance. a. Plexus of efferent vessels. 

 b. Lymph paths, c. Medullary cords. 

 d. Trabeculae. (K6lliker.) 



These opaque and vascular tracts are called the medullary cords of the 

 lymphatic gland. They are the only vascular parts of the organ ; as 

 the capillary bloodvessels never pass beyond them into the intervening 

 transparent spaces. The transparent spaces, situated between the 



