4o6 



GA ULE. 



[Vol. VIII. 



recall the results of Giirber's investigation, that the white 

 blood corpuscles increase under the influence of dryness, and 

 then consider that the eosinophilous cells are white blood 

 corpuscles, and that the follicle cells, if not white blood cor- 

 puscles, are closely allied to them in character, it then seems 

 possible that the summer elevations of these two curves may 



be in part the result of the dry- 

 ness, but only in part, for the 

 abundant nourishment, and pos- 

 sibly still another influence, 

 must be taken into account. 



Rana Temporaria. 



2 "o d ^ oi 



fc< 1=5 < S 1— > 



a 2 



< w o iz; Q 



3 



3 



^ e. "Nurse ''-Cell Curves. 



In general there are fewer 

 "nurse" cells in summer dur- 

 o ing the abundant food period, 

 more in November at its close, 

 and the most in February, 

 March and April, immediately 

 ^ preceding the period of copula- 

 tion. During the month of 

 copulation there are very few of 

 these cells in the spleen, but the 

 number increases again in the 

 male spleens in the month im- 

 mediately following, and in the 

 female spleens in the second month following the month of 

 copulation. The escidenta spleen is richer in "nurse" cells 

 than the temporaria. They are most abundant in the esculenta 

 spleen in March and April, in the temporaria spleen in March 

 and April. The curves of the species are typical. The male 

 spleens contain a greater number of "nurse" cells than the 

 female. 



A comparison of Figs, a and e indicates that the tcmpoi'afia 

 spleens contain few of these cells when the spleens are large 

 and more when the spleens are small. May and June spleens 

 are an exception, for here the first slight increase in size is ac- 



Fig. d. — Follicle-Cell Curves. 



