Weight Fluctuations in Frogs. 



145 



per cent., while seventeen hours later (over night), the animal was 

 dead, and the loss of weight had increased to 56.4 per cent, of the 

 original weight. This is rather larger than loss in weight com- 

 patible with life hitherto reported, but as it is known that the 

 seasonal condition of the animals has an important bearing in such 

 experiments, 1 and since the frogs employed were in the "winter" 

 condition, the relatively great loss in weight before death is not 

 considered extraordinary. 



A frog in which the brain was pithed before placing in the dry 

 cage lost 60 per cent, of its original weight in twenty-three hours, 



The behavior of partially dried frogs when placed in hypo-, 

 iso- and hypertonic salt solutions is interesting. In one such 

 experiment, the original weight was 19 gm. and twenty-three 

 hours after placing in a dry cage 1 1 gm. The frog was then placed 

 in 0.2 per cent. NaCl solution. Fifty minutes later it weighed 18 

 gm., and seven hours later 25 gm. Twenty-four hours later 

 the weight was 24 gm., from which point, with slight fluctuations, 

 it gradually decreased until seventy-two hours after placing it in 

 salt solution it was 22 gm. The animal remained lively. 



Another frog weighing 18.5 gm. was allowed to dry until it 

 weighed 11.8 gm., which took place within twenty-three hours. 

 It was then placed in 0.6 per cent. NaCl solution. Fifty minutes 

 later it weighed 16 gm., and seven hours later, 22 gm. Fifty-five 

 hours after being placed in the solution, the weight was 28.2 gm., 

 but seventeen hours later it was 24.5 gm. At this time the frog 

 was alive and in good condition. 



Another frog similarly dried and placed in 0.7 per cent. NaCl 

 solution, showed a more gradual and less pronounced increase in 

 weight, and was active and in good condition seventy-two hours 

 later. Frogs dried and placed in 0.8 per cent., 0.9 per cent, and 

 I per cent. NaCl solutions barely regained their original weight, 

 and the process was much more gradual. They died soon after 

 being placed in the NaCl, but in the case of 1 per cent. NaCl the 

 animal lived for somewhat longer than seven hours. In stronger 

 solutions, body weight was not regained, and death soon occurred. 



Since it is known that water content influences tissue function, 

 this note is offered with the view of directing attention to the 



1 Donaldson and Schoemaker, Jr. of Comparative Neurology, 1909, X, 109. 



