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GA ULE. 



[Vol. VIII. 



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J and 9, it is easy to get a general impression of the suc- 

 cession of the curve elevations and depressions and their pos- 

 sible relation to the two periods of the yearly cycle. We see, 

 then, that these two periods correspond chiefly to the food 

 or summer period, and to the hunger or winter period. The 

 spleens are much larger in summer than in winter, the increase 

 in size being accompanied in June and July by an increase in 

 the number of white-blood corpuscles, that is, eosinophi- 



lous cells, follicle cells, and 



Rana Temporaria. 



"nurse cells, later, m August 

 ■"' ■" '-^ . 



and September, by the increased 



amount of blood, as indicated by 

 the number of red blood cor- 

 puscles and the diameter of the 

 blood - vessels and capillaries. 

 As the food period comes to a 

 close, the number of white- 

 blood corpuscles, pigment, and 

 follicle cells increase again 

 to fall below the average pro- 

 portion during the winter. Dur- 

 ing the months directly pre- 

 ceding the period of copulation, 

 the number of white blood cor- 

 puscles and the amount of pig- 

 ment increases. 



The curves of temporaria 

 teach us that the teviporaria 

 spleens are smaller than those 

 of esculenta, and that the eosinophilous cells are character- 

 istic of this species. The outlines of the blood, "nurse" 

 cells, pigment, cytozoa, follicle cell, and plasmosoma curves 

 are similar in the two sexes, which indicates that the annual 

 chemical processes are on the whole alike in both. 



The curves of esculenta teach that the spleens are larger 

 than the temporaria spleens, and that follicle cells, pigment, 

 cytozoa, and a greater of protoplasm are characteristic of this 

 species. The outline of the "nurse" cell and follicle cell 



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Fig. k. — Figures of Cell-Division. 



