286 DR A. J. WHITING ON THE 



with hematoxylin ; but sometimes they are small, nearly round and stain deeply. The 

 cell plate and processes are clear and glassy. There are many long connective tissue 

 strands in the stroma, some of which form the walls of the venous sinuses, and with them 

 the stellate cells are directly continuous. 



The corpuscular elements in the pulp of the spleen of a young Rabbit (probably 

 about half grown) are of four kinds : — (1) Lymphoid cells ; (2) giant cells ; (3) hyaline 

 protoplasmic corpuscles or erythroblasts ; and (4) eosinophilous cells. 



The giant cells, which are in considerable numbers, about two hundred in a section, 

 resemble those described in other animals. They show well marked karyokinetic figures. 

 The cell protoplasm shows numerous vacuoles, some of which are apposed to the central 

 nuclear heap. The erythroblasts are not very numerous, while they occupy a position 

 around the giant cells as in other spleens. Eosinophilous cells are comparatively 

 numerous : they often occur in groups that are composed sometimes of as many as twenty 

 cells. 



In the splenic pulp of an adult Rabbit there occur all the kinds of cells met with 

 in the preceding spleen, and also some cells of another sort. Within the venous sinuses 

 especially, but also in the pulp, are a few cells about a third of the size of the giant cells, 

 consisting of red-stained granular protoplasm that surrounds two or three nuclei, and 

 a variable number of clear round areas which, although something like red blood- 

 corpuscles, seem to be vacuoles. Only about four or five characteristic giant cells occur 

 in a section. 



In the spleen of a second adult Rabbit the venous sinuses contain many such special 

 vacuolated cells, and the cell substance between the vacuoles contains a large number 

 of yellow pigment graiDS. The average diameter of these cells is about 16 /a, while the 

 vacuoles measure about 6 /a. There are apparently no giant cells either in the follicles 

 or in the pulp. 



In the pulp reticulum of the spleen of the Rat there are fewer long connective tissue 

 strands than in that of the rabbit, their place being taken by muscular bundles derived 

 from the trabecule, with which the supporting cells are continuous. These cells are not 

 so characteristically stellate, and their processes, which are slightly more thread-like, branch 

 and anastomose more, hence the meshes of the network are relatively more numerous 

 and closer together, while the nuclei are relatively fewer. 



The corpuscular elements of the pulp in the adult Rat are of four kinds : — (l) 

 Lymphoid cells of different sizes ; (2) erythroblasts ; (3) giant cells, larger and smaller ; 

 and (4) pigment-holding cells. 



The giant cells are like those described in other spleens, they number about twenty 

 or thirty in a section. Their nuclei sometimes contain so little chromatin as to be seen 

 only with difficulty after staining with hematoxylin, while the diffuse chromatin of the 

 nuclei of the ery throblast sometimes stains so deeply as to hide the network. The central 

 nuclear heap often shows active budding. Those cells that seem to be small giant cells 

 are only about a half or a fourth the size of the larger, but they are much more numerous, 



