des Agens Physiques sur la Vie. 145 



also been sealed up during similar periods without perishing. 

 Possibly some hole or crevice might have admitted a little 

 air. But, in Hevissant's experiment of 79, care seems to 

 have been taken to obviate this suspicion. 



Dr. Edwards, however, determined to put the question to 

 the test. He enclosed ten out of fifteen frogs in thick wooden 

 boxes, and filled the interstices with plaster, covering them over 

 with the same substance, the toads lying each in a central 

 hole or bed. The other five toads were at the same time 

 submersed in water, and at the expiration of eight hours they 

 were found to be dead. In sixteen hours more, one toad was 

 taken from a box and found to be lively, and was reconsigned 

 to its prison. On the sixteenth day the toads in the boxes 

 were discovered alive, and thus the fact was established that 

 these animals can live far longer in a state of asphyxy con- 

 fined in solid substances, than when submersed in water. 

 This was confirmed by repeated trials on salamanders, frogs, 

 and toads. The frogs perished quickest. 



Thus an extraordinary fact is established, as regarding 

 reptiles, since it affords an exception to the general rule that 

 all animals require a constant supply of fresh air for the 

 maintenance of their existence. 



Similar trials were repeated in sand, and with the same 

 results. 



Dr. Edwards found that although a certain quantity of air 

 enters the boxes and sand, yet that it is far too little to main- 

 tain life. His conclusion, therefore, stands, that animals of 

 the kind employed can live longer in solid substances than in 

 a limited quantity of dry air. 



It remains, however, to be considered in what manner these 

 animals have their lives extended beyond those exposed to 

 the action of a body of air. Dr. Edwards supposes the 

 moisture of the sand to be one cause, since in the dry air the 

 animals become desiccated, the cutaneous transpiration being 

 lost in one case, and retained in the other, by the exclusion of 

 air. A rapid and abundant transpiration from the body, 

 united with deficiency of air, seems to be a greater cause of 

 dissolution than confinement in solid substances wherein there 

 is no waste by transpiration. 



The author's inquiries are next directed to the influence of 

 temperature upon animals of cold blood, and two and forty 

 experiments are practised upon this subject, from the month 

 of July to September following, during which period frogs 

 were submersed in aerated water, with a view of settling the 

 duration of life, acted on by varieties of temperature. Th^ 



JULY— OCT. 1827. L 



