1 62 



THE BIOLOGY OF THE FROG 



CHAP. 



by a slow diminution during tiie winter and then a rapid 

 falling off in the spring. The amount of glycogen in the 

 liver alone was found to increase and decrease along with 

 that of the body as a whole. The amount of glycogen in the 

 liver was found to be more variable than the glycogen con- 

 tent of the rest of the body, exceeding the latter in the fall 

 and early winter, while in the fall the reverse relation obtains. 

 The variations in the weight of the liver as a whole have 

 been studied in detail by Gaule in Rana esculenta. The 

 weight of the liver was found to be relatively greater in 

 males than in females and to possess a somewhat greater 

 range of seasonal variations. The following table taken from 

 Gaule's estimates shows the weight of the liver per gram of 

 body weight in the two sexes during the different months of 

 the year : — 



January 

 February . 

 March . . 

 April . . 

 May . . 

 June . . 

 Jiily. . . 

 August . . 

 September 

 October 

 November . 

 December , 



The numbers in the table represent the average weights 

 of the livers and bodies of a number of individuals (usually 

 15 to 25) sacrificed for each determination. The variations 



