298 Dr. Edwards, De Vlnfiuence 



solved in the water to a lower standard than is requisite for 

 the proper aerification of their blood, thus renewing their 

 supply of o.z'yg'^n. 



The functions of this class of animals have always been 

 obscure, and their phenomena are different from those of 

 others. Different species of fish die at various periods when 

 deprived of water, some in a few minutes, others in a few 

 hours ; and it appears that their dissolution arises not so 

 much from incapability of atmospheric respiration (for the 

 experiments of Sylvester prove that they can respire pure 

 air), as from the different state of the air. :>nv> h^);; 

 • Some experiments on lizards, S7iakes, and turtles conclude 

 the researches among cold-blooded anim.als. The skins of 

 these, like those of the frogs and salamanders, received a 

 vivifying influence from the air, mainly acting, in conjunc- 

 tion with pulmonary respiration, to promote their existence. 

 Snakes and turtle, their pulmonary respiration being insu- 

 lated, from their skins being guarded from atmospheric 

 influence, were found alive ; but the lizards died in a few 

 hours, when the vivifying contact of the air was removed 

 from their bodies, and they breathed only by their mouths. 

 Animals naturally defended by scales transpire much less 

 than such as have their skins free. Thus frogs, toads, and 

 salamanders yielded more by perspiration than lizards, 

 snakes, and turtle, in a given time ; and the porosity of the 

 skin of course regulates the facility of transpiration in all 

 cases. 



With these experiments and remarks. Dr. Edwards con- 

 cludes the second part of his researches. The third part 

 includes animals of warm blood, in which will be found 

 some curious and interesting remarks on the heat of young 

 animals compared with that of adults. 



Dr. Edwards refutes the common notion of young animals 

 being necessarily hotter than adults. The heat of young- 

 puppies was very near that of the parent, or one or two 

 degrees less, but this variation was not constant. Some 

 new-born kittens and rabbits were also subjected to similar 

 trials, and the results led to a conclusion that the tempera- 

 ture of young animals is less than that of adults. 



According to these experiments, the power of resisting the 

 cooling influence of the air acquires force as the animal 

 grows up ; and those examples related, in which artificial 

 covering was adopted, show that nudity is not the only cause 

 ef the reduction of heat, which is, in fact, more referrible 



