in regard to Respiration-. 261 



o:x\'gen by the lungs in comparison of that absorbed by the 

 skin, though it has been generally believed that in this class 

 of" animals, as in others which are higher, the destruction 

 of the oxvgen gas of the atmosphere ought to be referred 

 entirely tolhls organ. Some kinds of amphibia also which 

 •I deprived of their lungs lived much longer in the open air 

 than those which had lungs when I inclosed them in me- 

 phitic air, where they were entirely deprived of oxygen 

 gas. I discovered also that some of them die much sooner 

 when their skin is slightly covered with a spirit of wine 

 varnish. The cause of this difference is evident : by meanS 

 of this varnish these animals then not only cease to absorb 

 oxygen, but they can no longer free themselves from the 

 carbonic acid which ought to be exhaled, and its expulsion 

 is necessary to their existence; while in the mephitic g-ases 

 in which I placed these animals I always found carbonic 

 acid in its gaseous state. 



I was, however, able to ascertain the exact absorption of 

 oxygen by the cutaneous organ, without depriving amphibia 

 of their lungs : 1 confined their bodies in receivers in such 

 a manner that they had no communication with exterior 

 air, while at the same time they had their heads out in the 

 air, in which they could freely breathe. I thus clearly as- 

 certained, that the absorption made by these animals when 

 dead is only a continuation of that which they made during 

 life. 



Hitherto I have spoken only of the four classes of cold- 

 blooded animals; it therefore remains that I should say 

 something of birds and the mammalia : as the latter have a 

 greater relation to man, they ought to be more interesting to 

 our curiosity. Birds also absorbed oxygen in the experi- 

 ments to which 1 subjected them, both when living and 

 dead; and even their parts, such as the brain, muscles, in- 

 terior parts, and also the skin. I shut them up alive, like 

 the amphibia, in vessels in such a manner that they breath- 

 ed in the open air without these vessels; which furnished 

 ine with the means of ascertaining the quantity of the ab- 

 sorption bv the cutaneous organ. 



The mammalia, who are in the order of quadrupeds, gave 

 me results similar to those exhibited by birds; but I obtain- 

 fcd others of great importance from that singular species of 

 quadruped*; which are rendered lethargic by the air, or 

 which, as is conmionly said, sleep during the winter. 



1 observed that the phapnomcna of respiration change in 



these animals according to the different degrees of the ttm- 



perature ot llie atmosphere, and that similar phienomenaare 



K 3 remarked 



