No. 2.] CHANGES IN THE SPLEEN OF THE FROG. 403 



Description and Comparison of the Curves. 



a. Size Curves. 



The general features of the curves indicate that the spleens 

 are larger in summer during the food-period than in winter. 

 They are smallest at the close of the food period and before 

 the commencement of the same, 

 or immediately preceding copu- 

 lation. The csciilenta spleens 

 are larger than the temporaria 

 spleens. There is a greater 

 difference in size between the 

 summer and winter spleen of 

 esculenta, than between the 

 summer and winter spleen of 

 tcmpoi-avia. The difference in 

 size of the summer and winter 

 spleen is greater with the male 

 than with the female. 



43 



s 



(3 



3 



« 4 



1.5 



b. Blood Curves. 



The spleens are seen to con- 

 tain less blood in the first 

 months succeeding copulation 

 than at almost any other time 

 of the year, although the period 

 of abundant food has already 

 begun. During the remaining 

 of the food-period, 

 September, October, 

 a maximum quantity 



3 



2.5 



2 



1.5 



Jl.O 

 .5 

 



8.5 



1.5 



1.0 



.6 

 



months 

 August, 

 contain 

 of blood. 



The curves of the male and 

 female temporaria are very simi- 

 lar, whereas those of the male and female esculenta are unlike. 

 The spleens of both sexes of temporaria contain a small quan- 

 tity of blood during the hunger period. In May, the month 



Fig. a. — Size Curves. 



