204 DR A. J. WHITING ON THE 



processes of nucleated plate-like cells, and is continuous with the supporting framework 

 of the spleen. 



(2) The cellular elements of the pulp may be classified as follows : — 



1. Lymphoid Cells. 



(1) Uninucleated. 



(2) Multinucleated. 



2. Protoplasmic Corpuscles. 



(1) Coarsely granular. 



(2) Hyaline. 



(a) Erythroblasts. 



(b) Nucleated red cells 



(3) Eosinophilous cells. 



3. Pigment-holding Cells. 



4. Special Cells. 



(1) Giant cells. 



(2) Multinucleated vacuolated cells. 



(3) Uninucleated vacuolated cells. 



(3) The lymphoid cells are nearly all uninucleated, with little, if any, peripheral 

 protoplasm, and resemble the small lymphoid cells of the outer zone of the follicles. 



(4) The multinucleated lymphoid cells have a considerable amount of finely granular 

 protoplasm that stains faintly, if at all, with eosine ; and they are probably derived 

 from the blood. 



(5) The protoplasm of the protoplasmic corpuscles stains deeply with eosine. 



(6) Erythroblasts and nucleated red cells are more numerous in those spleens that 

 contain giant cells, and as a rule they appear to be most numerous in those that 

 contain most giant cells. 



(7) Erythroblasts are sometimes seen in the substance of the giant cells, sometimes 

 in bulgings of their surface, and often in mouth-like openings on their surface. 



(8) The erythroblasts multiply by karyokinesis. 



(9) The hyaline perinuclear protoplasm of the erythroblasts seems to be slightly 

 tinted with haemoglobin as Bizzozero # maintained. 



(10) The pigment of the pigment-holding cells either occurs in the form of granules 

 imbedded in a basis of coarsely granular protoplasm, or it, along with a nucleus, entirely 

 fills the cell. It is probable that the pigment granules have been taken up by the 

 pigment-cells, that the pigment-cells are phagocytes, and of the nature of leucocytes. 



(11) Giant cells occur, probably invariably, in the spleen of Mammals during early 

 extra-uterine life, and usually also in late intra-uterine life. They occur in considerable 

 numbers in the spleen of some small Mammals, for example the mouse, the rat, and the 

 hedgehog, during adult life. And they may occur in small numbers in the spleen of 

 individual instances of other adult Mammals, for example the dog and the cat. 



* Bizzozero, cited by Muir (47), p. 502. 



