406 



LYMPH-FOLLICLES. 



lymphatics. The cavities of th peritoneum, pleura, pericardium, tunica vaginalis 

 testis, arachnoid space, aqueous chambers of the eye (Schwalbe), and the 

 labyrinth of the ear, are true lymph-cavities, and the fluid they contain is to 

 be regarded as lymph. 



(6.) Free open pores have been observed on some mucous membranes, which are 

 regarded as the origin of lymphatics, e.g., in the bronchi (Klein) the nasal 

 mucous membrane (Hjalmar-Heiberg), in the trachea and larynx. 



The larger lymphatics resemble in structure the veins of corresponding size. 

 The valves are particularly numerous in the lymphatics, so that a distended 

 lymphatic resembles a chain of pearls. [Lymphatics have dilations here and there 

 in their course (Fig. 158).] 



197. The Lymph-Glands. 



The so-called lymphatic glands belong to the lymph apparatus. 

 They are incorrectly termed glands, as they are much branched 

 lacunar labyrinthine spaces merely composed of adenoid tissue, and 

 intercalated in the course of the lymphatic vessels. 



There are simple and compound lymph-glands. 



(1.) The simple lymph-glands, or, more correctly, lymph-follicles, are small 

 rounded bodies, about the size of a pin-head. They consist of a mass of adenoid 

 tissue (Fig. 161, A), i.e., of a very delicate net-work of fine reticular fibres with 

 nuclei at their points of intersection, and in the spaces of the mesh-work lie the 

 lymph and the lymph-corpuscles. Near the surface, the tissue is somewhat denser, 

 where it forms a capsule, which is not however a true capsule, as it is permeated 

 with numerous small sponge-like spaces. Small lymphatics come directly into 

 contact with these lymph -follicles, and often cover their surface in the form of a 



Fig. 161. 



Two lymph-follicles A, a small follicle highly magnified, showing the adenoid 

 reticulum ; B, a follicle less highly magnified, showing injected blood-vessels. 



close net-work. The surface of the lymph-follicles is not unfrequently placed in 

 the wall of a lymph-vessel, so that it is directly bathed by the lymph-stream. 

 Although no direct canal-like opening leads from the follicle into the lymphatic 

 stream, in relation with it a communication must exist, and this is obtained by the 

 numerous spaces in the follicle itself, so that a lymph-follicle is a true lymphatic 

 apparatus (Briicke) whose juices and lymph-corpuscles can pass into the nearest 

 lymphatic. The follicles are surrounded by a net-work of blood-vessels which 



