LYMPHOID TISSUE, LYMPH-NODULES, AND LYMPH-GLANDS. 2OI 



in the different types studied. Warthin has discussed more fully 

 than other observers the hemolymph glands of man, and his account 

 will here be followed in the main. It may be parenthetically stated 

 that the hemolymph glands are numerous and well developed in 

 the sheep (Warthin, Weidenreich) ; not so well differentiated in the 

 dog and cat ; on the other hand, well developed in the rat 

 (Lewis). 



We learn from the account of Warthin that the hemolymph 

 glands are numerous in man, in the prevertebral retroperitoneal 

 region, in the cervical region, and less numerous in the thorax. 

 They vary in size from that of several millimeters to that of several 

 centimeters. They present a variety of structure, depending mainly 

 upon the arrangement of the lymphoid tissue and blood-sinuses. 

 The great majority of these glands show a resemblance in structure 

 to splenic tissue (splenolymph glands) ; others resemble more 

 closely marrow-tissue (marrow lymph-glands). Between the two 

 varieties of lymph-glands there are found transition forms, as also 

 between these and lymph-glands (Warthin). 



The hemolymph glands (splenolymph glands) are surrounded 

 by a capsule varying in thickness and composed of white fibrous 

 and elastic tissue and nonstriated muscle-cells. From it trabeculae 

 of the same structure pass into the gland, which after division are 

 lost in the substance of the gland. Beneath the capsule there is 

 found a continuous or discontinuous blood-sinus, bridged over 

 by reticular fibers, from which anastomosing sinuses pass to the 

 interior of the gland. These blood-sinuses are, in part at least, lined' 

 by endothelial cells. The sinuses in the gland substance are also 

 bridged by trabeculae and reticular fibers. The sinuses divide the 

 lymphoid tissue into anastomosing masses and cords. This tissue 

 consists of an adenoid reticulum, in the meshes of which are found 

 white and red blood-cells. The small lymphocytes are numerous; 

 next in frequency are found the mononuclear leucocytes ; transi- 

 tional and polymorphonuclear cells. Basophile and eosinophile 

 cells are also found. According to Weidenreich, the eosinophile 

 cells are numerous ; he is also of the opinion that the eosinophile 

 granules are derived from disintegrating red blood-cells. In the 

 reticulum and in the blood-sinuses are found mononuclear phago- 

 cytes, the origin of which has not been fully determined. Certain 

 observers (Schumacher, Weidenreich) trace their origin to the cells 

 of the reticulum ; Thoma regards them as developed from endo- 

 thelial cells, while Drummond and others regard them as altered 

 leucocytes. They contain disintegrating red blood-cells and pig- 

 ment (according to Weidenreich, eosinophile cells). The majority 

 of the hemolymph glands present a hilum through which the 

 blood-vessels enter. The arteries, soon after entering the gland, 

 divide into smaller branches, certain of which communicate directly 

 through blood-capillaries with the blood-sinuses (Lewis) ; others 

 pass to the adenoid tissue. The larger veins are in the trabeculse 



