198 



BLOOD AND BLOOD-FORMING ORGANS. 



at the hilum. The whole gland is surrounded by a capsule consist- 

 ing of two layers : the outer is made up of a loose, and the inner of 

 a more compact, connective tissue in which elastic fibers and a few 

 smooth muscle-fibers are imbedded. Portions of the inner layer 

 pass into the substance of the gland to form septa, or trabeculce, by 

 means of which the organ is divided into a number of imperfectly 

 separated compartments. These trabeculae may be very well 

 developed, as in the lymph-glands of the domestic cattle, or only 



Fig. 161. Transverse section of human cervical lymph-gland, showing the general 

 structure of a lymph-gland ; X J 8. Af> Blood-vessels ; ff, fibrous capsule ; h, hilum ; 

 kz, germ-center ; nl, lymph-nodule ; sc, cortical substance ; gm, medullary substance ; 

 tr, trabeculse ; via, afferent lymph-vessels ; vie, efferent lymph-vessels ( " Atlas and 

 Epitome of Human Histology," Sobotta). 



poorly developed, as in the human lymph-glands, where they are 

 often almost wanting. The lymphoid tissue of the gland is so 

 distributed that at its periphery a large number of more or less 

 clearly defined lymph-nodules are found, which are in part separated 

 from each other by the trabeculae just described, the cortical nodules. 

 The nodules are structural units and have a typical blood supply, 

 and are in structure like the lymph-nodules of simple and ag- 



