HEMOLYMPH NODES 153 



Blood vessels. The arteries enter the lymphatic node at its 

 hilum, and, following the trabeculae within which they lie, are dis- 

 tributed to all portions of the organ. In the medulla branches 

 are distributed to the lymphatic cords, in which they form a wide- 

 ineshed capillary plexus. 



The terminal branches of the primary divisions of the afferent 

 artery are distributed to the follicles of the cortex. A single fol- 

 licular branch (Calvert*) enters the follicle and passes straight 

 toward its center, where it breaks into a plexus of divergent cap- 

 illaries which unite at the surface of the follicle to form small 

 venous radicals. 



The veins follow the interfollicular trabeculae in their course 

 toward the medulla, where they enter the medullary trabeculae, are 

 augmented by venous radicals from the capillary plexuses of this 

 portion of the gland, and thence follow the trabeculae to the hilum, 

 where they unite to form the efferent vein. 



Certain of the arteries also pass from the medulla through the 

 interfollicular trabeculae to the capsule of the gland, to which they 

 supply a capillary plexus. The blood is returned through veins 

 which retrace the course of the arteries and enter the large veins 

 of the medullary trabeculae. 



HEMOLYMPH NODES. These structures, which closely re- 

 semble the lymphatic nodes, were first described by H. Gibbs,f in 

 1884. He found them in the connective tissue, between the renal 

 artery and vein, in the human subject. They have since been 

 found in the prevertebral connective tissue, and in the mediasti- 

 num and mesentery. They are larger and more numerous in the 

 ruminants, ox, sheep, etc., than in man. Their size varies from 

 that of a millet seed to that of a pea. In color they closely re- 

 semble a minute extravasation of blood. 



These organs are essentially lymphatic structures in which the 

 lymphoid tissue is arranged in the form of cords rather than in 

 follicles. The node is inclosed by a fibrous capsule, beneath 

 which is a broad sinus filled with blood. In this fact lies the chief 

 distinguishing feature of these glands. 



The peripheral Uood sinus, which is analogous to the peripheral 

 lymphatic sinus of a lymphatic node, sends into the interior of 

 the organ a greater or less number of secondary sinuses. Based 

 largely upon the abundance of these secondary sinuses, the hemo- 



* Anat. Anz., 1897. f Quart. J. Mic. Sc. 



