DoNALDsoN-ScHOEMAKER, Nenmis System of Frogs. 113 



As this condensed table shows, the greatest loss in weight 

 is during the first days of captivity. All the frogs lose weight, 

 but the proportional loss is greater for the heavier individuals. 

 The irregularities in weight shown by Frogs III and IV may 

 depend on two things; first, the condition of the water-bladder, 

 which was usually, though not akvays, emptied before the frog 

 was weighed, and second, variations in the amount of water 

 absorbed. This latter is probably much the more important fac- 

 tor, although as variations in this amount are largely determined 

 by conditions existing within the frog itself, they are not readily 



controlled. 



TABLE II. 

 Frog. I II HI IV 



Percentage loss in 12 days i6% \ZcL \\d^ %ci^ 



The percentage loss of weight for the four frogs in ques- 

 tion is given in Table II. These data were used to correct the 

 body-weights of the spring frogs which had been kept for more 

 than a day in the laboratory. The body-weight thus corrected, 

 where necessary, is the one which appears in Table VII, given 

 farther on. 



That this loss of weight is peculiar to spring frogs which 

 have not yet recovered from the eftects of hibernation and 

 breeding, can be shown in the following way: 



On June 30th, five frogs were caught and put in the tank 



under the same conditions as the series tested during May. 



They were weighed each twenty-four hours, and we select the 



weights at three and four day intervals for the following table : 



TABLE III. 



No. of Frog. I II III IV V 



Weight wlien caught, June 30, 

 Weight July 3, 



Weight July 7, 



Numbers I and III died on the 9th of July, so Table III., 

 contains entries for three dates only. As will be seen. Frogs 

 I and II show a slight loss. This loss, however, is not nearly so 

 as large that found in the spring frogs. No. Ill shows a gain 

 and Nos. IV and V large losses. These small frogs were at 



