532 PHYSIOLOGY CHAP. 



cross the sinuses and enter the trabeculae, leaving eventually by 

 the hilum. 



The leucocytes which fill the meshes of the adenoid tissue, 

 both of the follicles and of the medullary cords, differ in no way 

 from those of the solitary follicles of the intestine. The follicles 

 of the alveolar glands also show a germinative centre, where many 

 leucocytes are seen in process of mitotic division (Fig. 251). 

 Mitosis can also be seen in the medullary cords, though less 

 freely. 



The preceding description of the functions of the solitary and 



Flo - 25 l- Alveolar tollicle withladjacent medullary cord of a lymphatic gland, in man. (Buhm.) 

 under oin ' mlt medullary corfl ' cg > g erminal centre, in which many leucocytes are seen 



agminated follicles applies perfectly to the lymphatic glands as 

 well. We may regard the former as simple terminal lympha- 

 poietic organs, which are found sparsely disseminated at the roots 

 of the lymphatic system; and the latter as complex lympha- 

 poietic organs, intercalated along the course of the lymphatic 

 vessels, and therefore, unlike the former, provided with afferent 

 and efferent vessels. 



After the microscopic work that has been done on the lymphatic 

 glands under various physiological and pathological conditions, 

 there can be no doubt that the leucocytes that subsequently pass 



