i6o 



THE BIOLOGY OF THE FROG 



CHAP. 



Average diameter 



of cells 

 Average diameter 



of nuclei 



NOVEMBER 



.0292 mm. 



.006 mm, 



DECEMBER 



.0162 mm. 



.0044 mm. 



.012 mm. 



.0076 mm, 



JUNE 



.0172 mm, 



.0065 mm. 



JULY 



.0274 mm. 



.0065 mm. 



Similar measurements by Funke gave results approximately 

 the same as those obtained by Miss Leonard. The minimum 

 size of the cells in R. temporaria according to Funke occurs 

 in May, the maximum in July and August. In R. esculenta 

 the minimum falls in June and the normal size is reached 

 two or three months later, but there is no well-defined period 

 of maximum growth. In both species the minimum size of 

 the liver cells as well as the liver as a whole occurs at the 

 time of breeding. 



The fat content of the liver was found by Funke to vary 

 in an irregular manner both in R. esculenta and R. temporaria. 

 In the first species the fat content of the liver in many 

 instances almost entirely disappeared in June. During the 

 summer fat is stored in the liver, and in the winter it suffers 

 very little diminution if it does not actually increase in 

 amount. In R. tempoj-aria the amount of fat in the liver is 

 very small compared with that in R. esculenta, and no defi- 

 nite conclusion could be drawn regarding the general course 

 of its seasonal changes. According to Langley's observa- 

 tions upon frogs in England, " the fat in the liver cells 

 reaches its maximum amount in February and March. In 

 January it is as a rule somewhat less. In April it rapidly 

 decreases, from May to December it is present in compara- 

 tively small though varying amounts. It is usually present 

 in minimum amount in September and October." 



Miss Leonard found that the relative proportion of blood 



