[CAMERON] HISTORY OF THE FROG 17 



The frog removed on May 14th, after complete immersion in water for 151 

 days, did not breathe for several seconds, then commenced to breathe feebly, trying 

 to touch the nares with its forelegs, as if they were choked up. The breathing 

 continued to be feeble and irregular until, after three minutes, the frog commenced 

 to be active, when breathing became normal. On the 15th its weight has fallen to 

 51 grams, and on the 29th to 46 grams. It was then very active and quite normal. 



(The actual absorption of water was therefore about 8 or 9 c.c.) 



These experiments show that frogs can survive throughout the 

 winter submerged under water. Also, that with increasing hardness 

 of water there is a greater tendency to the retention of nitrogen gas. 

 In the first experiment, early in the winter, this only occurred slightly 

 in two out of six cases. In the second experiment most of the frogs 

 died earlier, and contained large amounts of gas. It is uncertain to 

 what extent red leg was a contributing factor in producing death of 

 these frogs. 



It was noted in these and some preliminary experiments that 

 when the water in which the frogs were immersed rose above a certain 

 temperature absorption of water commenced. Further examination 

 indicated that a temperature above 16°C. produced a delayed ab- 

 sorption, the oedematous condition disappearing when the tempera- 

 ture fell distinctly below this figure. Even partial immersion of frogs 

 in one inch of water produced such effects, indicating that the pro- 

 duction of oedema is not due entirely to oxygen-deficiency. (The 

 rise of temperature was sometimes due to fall in water pressure in 

 the mains, so that the flow ceased, and the water in the immersion 

 vessel became stagnant and rose to room temperature.) 



That want of oxygen can also produce an oedema is shown by 

 the following experiment. 



A frog weighing 59.5 grams was immersed in a 350 c.c. conical flask, which 

 was completely filled with water, closed and kept at a temperature of 12 -14 . In 

 three hours about 3 c.c. of gas was given off, which was found to be nitrogen. After 

 14 hours the frog appeared to be dead. It was removed and weighed. The weight, 

 66 grams, indicated an absorption of 6.5 c.c. of water. It responded to all external 

 stimuli, even croaking. It recovered in five hours, in ten its weight had fallen to 

 63 grams, and in 33 hours to 61 grams. 



It was noted during these experiments that frogs can croak 

 under water even after immersion for some days, indicating separation 

 of nitrogen (and perhaps some carbon dioxide) as gas in the lungs. 

 From time to time in such immersed frogs bubbles of gas are given 

 oft' from mouth and nares. 



Freezing Experiment. 



While the experiments at low temperatures indicate that under 

 experimental conditions frogs can only be frozen to about one degree 



