No. 2.] CHANGES IN THE SPLEEN OF THE FROG. 405 



Figs, a and c we come to the conclusion that the cosinophi- 

 lous cells increase in number when the spleens diminish in 

 size. The April and May spleens are an exception, as they 

 contain very few eosinophilous cells, and yet the spleens 

 are comparatively small. By a comparison of Figs, b and c 

 we discover that the number of eosinophilous cells is very 

 large in June and July, when 

 the quantity of blood was found 

 to be especially small. 



Rana Temporaria. 



d. Follicle-Cell Curves. 



2 "S ^ >, 



•s 3 ^ I 



fe § <; S 



^ -2 ^- -3 



±- W Q. 2 > 



In general the spleens con- 

 tain more of these cells in the 

 hunger period than in the food 

 period. All the curves indicate 

 that the spleens contain a great 

 many of these cells in July and 

 very few in February and 

 March. 



The esculeiita spleens con- 

 tain more of these cell-groups 

 than the temporaria. The male 

 spleens contain more such cells 

 than the female. After almost 

 disappearing from the spleens in 

 August, September or October, 

 they become more abundant again in the male spleens in Sep- 

 tember or October, and in the female spleens in November. 

 A comparison of Figs, a and d indicate that the follicle cells 

 have something to do with the increase in size of the July 

 spleens — especially of the female spleens — and hence proba- 

 bly plays an important part in its function. Figs, b and d 

 teach us that during the summer the spleen is more abundantly 

 supplied with blood when the number of follicle cells decrease. 

 Figs, c and d show a similarity of general outline, the summer 

 elevations of the follicle-cell curves being coincident with or 

 succeeding those of the eosinophilous cell curves. If we 



Fig. c. — Eosinophilous-Cell Curves. 



