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HAND-BOOK OF PHYSIOLOGY. 



.shaped central mass bifurcates (Fig. 215) or divides into two or more 

 .smaller rounded or cord-like masses, and here joining with those from the 

 other alveoli, form a much closer arrangement of the gland tissue (Fig. 

 214, a) than in the cortex; spaces (Fig. 214, b) are left within those 

 anastomosing cords, in which are found portions of the trabecular mesh- 

 work and the continuation of the lymph sinus (b, c). 



The essential structure of lymphatic-gland substance resembles that 

 which was described as existing, in a simple form, in the interior of the 

 solitary and agminated intestinal follicles. 



The lymph enters the gland by several afferent vessels (Fig. 215, a.L) 

 which open beneath the capsule into the lymph -channel or lymph-path; 



FIG. 216. A small portion of medullary substance from a mesenteric gland of the ox. d, d, tra- 

 beculae; a, part of a cord of glandular substances from which all but a few of the lymph-corpuscles 

 have been washed out to show its supporting meshwork of retiform tissue and its capillary blood-ves- 

 sels (which have been injected, and are dark in the figure); 6, 6, lymph-sinus, of which the retiform 

 tissue is represented only at c, c. X 300. (.Kolliker.) 



.at the same time they lay aside all their coats except the endothelial 

 lining, which h continuous with the lining of the lymph-path. The 

 efferent vessels (Fig. 215, e.l. ) begin in the medullary part of the gland, 

 and are continuous with the lymph-path here as the aiferent vessels were 

 with the cortical portion; the endothelium of one is continuous with that 

 of the other. 



The efferent vessels leave the gland at the hilus, the more or less con- 

 cave inner side of the gland, and generally either at once or very soon 

 after join together to form a single vessel. 



Blood-vessels which enter and leave the gland at the hilus are freely 

 distributed to the trabecular tissue and to the gland-pulp (Fig. 216). 



