io2 ELEMENTS OF HISTOLOGY. [Chap. xin. 



These are not empty free spaces, but are filled with a 

 coarse reticulum of fibres, much coarser than the ade- 

 noid reticulum ; to it are attached large transparent 

 cell plates endotheloid plates. In some instances (as 

 in the calf) these cell-plates of the medullary sinuses 

 contain brownish pigment granules, which give to the 

 medulla of the gland a dark brown aspect. In the 

 meshes of the reticulum of the sinuses are contained 

 lymph corpuscles, the majority of which consist of a 

 relatively large protoplasmic body, and one or two 

 nuclei ; they show lively amoeboid movement; a few 

 small lymph corpuscles are also amongst them. 



The surface of the trabecula3 facing the lymph 

 sinuses is covered with a continuous layer of endothe- 

 lium (von Recklinghausen), and a similar endothelial 

 membrane, but not so complete, can be made out on 

 the surface of the cortical follicles and the medullary 

 cylinders. The endotheloid plates, as applied to the 

 reticulum of the sinuses, are stretched out, as it were, 

 between the endothelial membrane covering the sur- 

 face of the trabeculse on the one hand and that 

 covering the surface of the follicles and cylinders on 

 the other. 



In the mesenteric gland of the pig the distribution 

 of cortical follicles and medullary cylinders is almost 

 the reverse from that of other glands or in other 

 animals. 



134. The afferent lymphatic vessels having entered 

 the outer capsule of the gland, and having formed 

 there a dense plexus, open directly into the cortical 

 lymph sinuses. The medullary lymph sinuses lead 

 into lymphatic vessels, which leave the" gland per 

 hilum as the efferent vessels. 



Both afferent and efferent vessels are supplied 

 with valves. 



135. The course of the lymph through a lymphatic 

 gland is then simply this from the afferent vessels, 



