The Structure and Functions of the hfemolymph Glands and Spleen. 27 



In lisemal lymphatic glands, reticulum is abundant in the sinuses 

 and signs of active phagocytosis are always present; germ centres are 

 plentiful, situated usually near the outer border of the adenoid tissue. 

 In the cat they are found more frequently than in the dog, though 

 in this animal the sinuses are less irregular and numerous. 



In Rodentia the glands have a structure differing slightly from 

 typical hœmal glands. In rats a complete peripheral sinus is never 

 present; the lymphoid tissue in the case of the glands of the renal 

 group is collected to one side of the organ, while the other half is 

 occupied by a large sinus. From the adenoid tissue finger shaped 

 masses project and run through the sinus towards the capsule of the 

 opposite side: in these processes blood vessels pass to the lymphoid 

 tissue (pi. I. fig. 5; pi. II. fig. 13). Germ centres have been found in 

 one gland only, in which they were numerous. Trabeculae are usually 

 absent, and this may account for the unusual collection of the adenoid 

 tissue to one side of the gland, in contact with the capsule. 



In the splenic glands, the sinuses are distributed throughout the 

 l^^mphoid tissue, which is consequently broken up; they come to the 

 surface in certain places only, giving the blotchy appearance which 

 is so characteristic of the glands in this region. Signs of active 

 phagocytosis are always present, though the sinuses do not contain 

 many leucocytes. In the rdbhit the arrangement is somewhat similar, 

 but the blood sinuses are broken up by very numerous fine strands 

 of adenoid tissue and small trabeculae. Compared with the renal 

 hsemal glands of the rat the sinuses are small though very distinct, 

 and completely filled with phagocytes. This abundant blood destruc- 

 tion appears to be characteristic of the glands of Rodentia, and is by 

 no means limited to the rabbit. 



In the guinea ing, large masses of lymphoid tissue and many 

 germ centres occur, while the sinuses are small and broken up. Though 

 closely resembling hsemal lymphatic glands when observed in situ, 

 microscopic examination shows them to be similar to the splenic glands 

 of the rat. 



frequently been observed by those experimenting upon the result of obstruction 

 of the inferior vena cava on the flow of lymph. 



