278 DR A. J. WHITING ON THE 



more especially in the pulp immediately under the capsule, the red blood-corpuscles may 

 be seen in various stages of transformation. In some the perinuclear protoplasm shows 

 here and there faintly blue-stained areas ; in others the whole of the protoplasm is 

 slightly blue-stained ; in other cells the blue staining of the protoplasm is almost as 

 deep as that of the nucleus, and in others the nucleus cannot be distinguished. The 

 protoplasm breaks up into round, blue-stained, coarse granules, which at first appear to 

 be imbedded in a blue-stained homogeneous matrix, but are subsequently apparently free 

 within a cell capsule, when the position of the nucleus is indicated by an oval shaded 

 area near one pole of the cell. Ultimately the granules escape from the cell capsules, 

 and collect into large irregular masses that adhere to the walls of the venous sinuses, or 

 pass down by the venous channels into the parenchyma towards the larger veins near 

 the middle of the spleen. 



In the spleen of the Tortoise the reticulum of the pulp closely resembles that of the 

 frog's spleen. The cells that form it are, however, smaller and more delicate, and they 

 have more processes. The meshes are usually oval or round, but near the walls of the 

 veins, where the cell processes are thread-like, they are angular. The supporting cells are 

 continuous with the trabecular sheath of the veins, and with the inner muscular layer of 

 the capsule. The reticulum of the periarterial adenoid tissue seems to be continuous 

 with that of the pulp, but the former is altogether finer, the cell processes are thread-like, 

 and they stain more faintly with eosine. 



There are at least six different kinds of cells in the pulp ; these are : — (l) Lymphoid 

 cells, similar to those of the adenoid sheath but slightly larger, without peripheral proto- 

 plasm, and like free nuclei. (2) Protoplasmic corpuscles of round or oval shape, which 

 vary considerably in size but are usually four or five times larger than a lymphoid cell. 

 Each has usually a single nucleus, which is round, and at least half the size of the whole 

 cell. The protoplasm is finely granular, and stains deeply pink with eosine. Similar 

 cells, but smaller and staining more deeply with eosine, occur in clumps here and there 

 throughout the pulp. (3) There arc a few eosinophilous cells, which are more numerous 

 just under the capsule than elsewhere. (4) Scattered in large numbers throughout the 

 pulp are very small cells, oval, or nearly round, each having a single, round, deeply 

 stained nucleus. The whole cell is about a half and the nucleus about a fourth of the 

 size of a lymphoid cell. The rim of perinuclear protoplasm is hyaline and stains but 

 slightly with eosine. The nucleus is almost vitreous in appearance, and has no nucleolus. 

 (5) There is a small proportion of cells that contain pigment, which are about ten times 

 larger than the lymphoid cells. Each has a single nucleus, little if any protoplasm, and 

 is filled with golden yellow granules. Sometimes a cell may be seen having not only 

 pigment granules but also granules that stain very deeply with eosine like those of the 

 eosinophilous cells. (G) Giant cells occur in considerable numbers. They vary much in 

 size, from about 16 to 22 ft in diameter. They consist of granular protoplasm that 

 stains not very deeply with eosine, in which is imbedded one large round nucleus, and 

 often in addition several small nuclei that resemble lymphoid cells in size and shape, and 



