No. 2.] CHANGES IN THE SPLEEN OF THE FROG. 399 



frog, for the cell-elements which form the bulk of the splenic 

 tissue are exceedingly varied in kind and quantity. 



Cells and Cell-Elements of the Spleen. 



These are : I. The cells of the blood, stained with the four 

 coloring fluids mentioned above, were described in " Methods of 

 Fixing and Staining the Elements of the Blood " already cited. 

 The fourth staining fluid, safranin, changes the picture in but 

 few points. The nuclei of the red blood corpuscles often show 

 a great affinity for it and certain nucleoli, called by Gaule 

 plasmosomes, hold the color fast. The blood corpuscles com- 

 prise, a, the red blood corpuscles, b, the white blood corpuscles 

 or leucocytes, including the " Halena toflacts " the eosino- 

 philous cells, the amoebocytes, the "nurse" cells or the 

 endotheloid cells. 



II. The endothelial cells and the cells of the adventitia 

 play a comparatively insignificant part in the spleen of the 

 frog. 



III. Cells resembling those of the Malpighian corpuscles of 

 the mammal spleen, which I shall designate follicle cells. 

 Groups of these cells are so densely crowded with nuclei, that 

 one can scarcely distinguish the protoplasm as such. They do 

 not always occur in the forms by which the Malpighian corpus- 

 cles are usually illustrated but in very irregular forms, occasion- 

 ally making a large proportion of the splenic tissue. At 

 times the neuclei are larger and have distinct nucleoli, at others 

 they are firmly granulated or almost homogenious in appear- 

 ance. In certain spleens the cells are interspersed with 

 eosinophilous cells or the eosinophilous cells circumscribe 

 the group of follicle cells, in other spleens one sees cells in 

 the process of division, in others a part of the cells are 

 displaced by pigment. Occasionlly one finds a partially 

 developed or imperfect red blood corpuscle imbeded between 

 the nuclei. 



IV. The pigment of the spleen is black, brown, yellow or 

 yellowish grey varying as well in color as in quantity at 

 different seasons and in the different species. 



