S53 
i 
662. Besides this exhalation of carbonic matter 
by the respiratory organs of animals, many facts tend 
to prove, that, during the continuance of living ac- 
tion, a similar change is effected in the air by the 
skin. Spallanzani found that some insects, which 
possess no stigmata, consumed the oxygen gas of the 
air by the medium of their skin ; and the same of- 
fice must be performed by the skin in many worms 
and zoophytes, which possess no other distinct respira- 
tory organ. Spallanzani farther observed, that the 
skins of fishes effected changes in the air similar to 
those produced by the gills * ; and M. M. Proven- 
9 al and Humboldt found, likewise, that the water in 
which the bodies of these animals had been confined, 
afforded the same aeriform products as when they 
were permitted to breathe by their gills f. In the 
experiments of Spallanzani, the skins of serpents 
were found also to consume the oxygen of the air, 
and to produce carbonic acid like the lungs t; and 
frogs, after being deprived of their lungs, still lived 
and consumed oxygen gas, which they appeared to 
effect by the action of their cutaneous organ . 
Hence, then, the power of the skin to convert the 
oxygen gas of the air into carbonic acid seems to be 
possessed by all the lower animals. 
663. From the results of various experiments by 
De Milly, Cruickshank, Abernethy and Jurine, we 
were before led to conclude (147.)> that carbonic acid 
* Rapports, &c. torn. i. p, 187 
t Mem. d'Arcueil, torn. ii. 
: Rapports, &c, t. i, p. 250. Ibid. p. 469- 
z 
