1892 - 93 .] Dr Whiting on Histology of the Spleen. 
23 
The reticulum of the splenic pulp is formed by the anastomosing 
expanded processes of nucleated plate-like cells, and is continuous 
with the supporting framework of the spleen. 
The cellular elements of the pulp are of four principal kinds — 
lymphoid cells, protoplasmic corpuscles, cells containing pigment — 
probably phagocytes, and special cells of the nature of giant cells. 
The lymphoid cells are nearly all small and uninucleated, and are 
probably derived from the follicles. Multinucleated lymphoid cells 
are few in number, and are probably derived from the blood. 
The protoplasmic corpuscles are of three kinds — coarsely granular, 
hyaline (and these are either erythroblasts or nucleated red cells), 
and eosinophilous cells. 
Giant cells occur in the spleen of mammals during late intra- 
uterine and early extra-uterine life, and usually in large numbers. 
They occur during adult life, in considerable numbers, in the spleen 
of some small mammals, as the mouse, rat, and hedgehog. Appar- 
ently homologous cells were found in the spleen of the tortoise. 
They are associated with numerous erythroblasts and nucleated red 
cells in the pulp and frequently with active karyokinesis in the 
follicles, and therefore seem to be a concomitant 'of the haematopoietic 
activity of the spleen. They usually possess a large central nucleus 
that gives off buds which become isolated. The giant cells 
were never seen to contain red corpuscles, as has been stated by 
those who regard them as destroyers of red corpuscles. The author 
believes them not to be phagocytes. They mostly occur in the 
pulp, but may sometimes be seen in the radicles of the splenic vein. 
Bizzozero and Salvioli have shown that when dogs and guinea-pigs 
are rendered anaemic by copious blood-letting, the spleen takes an 
active part in the production of nucleated red-blood cells. If the 
multinucleated giant cells are phagocytes, one would scarcely expect 
their number to be increased when the spleen is called upon to 
increase its blood-forming activity. The author examined the spleens 
of five dogs that had been rendered anaemic by loss of blood (three 
of them kindly given to him by Dr Eobert Muir), and in all of them 
there was a great increase in the number of giant cells found, 
with large numbers of erythroblasts and nucleated red cells. On 
the other hand, it has been ascertained by Neumann and Freyer and 
by Bizzozero and Salvioli that in the rabbit artificial anaemia does 
