830 EXPERIMENTS OF EDWARDS. 



when raised to 108, they never lived above two 

 minutes. He also found that frogs could live in 

 a vessel containing \1\ pints of aerated water, 

 when changed every day, from the 4th of Decem- 

 ber till the 25th of February; showing that they 

 are really amphibious at temperatures from 32 

 to 51. He further ascertained that fishes live 

 much longer in water deprived of air, at tem- 

 peratures below than above 50. (Influence of 

 Phys. Agents, p. 17.) 



The above experiments prove only, that when 

 the circulation of frogs and other batrachians is 

 partially suspended by cold, they require less air 

 to maintain a low degree of vitality, than when 

 the circulation is increased by placing them in a 

 higher temperature. As a proof of this, Dr. Ed- 

 wards himself informs us, that frogs lived twice 

 as long under water at 50 on the 23rd of Novem- 

 ber, as when immersed in water of the same tem- 

 perature during summer, showing that when 

 the activity of their functions is greatly dimin- 

 ished by the coldness of approaching winter, 

 there is air enough in water to support their 

 feeble vitality for a long time ; but that when 

 their circulation, respiration, and general acti- 

 vity are augmented by the higher temperature 

 of summer, they require more air than water 

 contains ; therefore die in a much shorter time, 

 and, perhaps, in two minutes or less, when con- 

 fined under water at 108. 



