490 RESPIRATION. 



paring the relative quantities of carbonic acid exhaled in the 

 twenty-four hours. According to this observer, the skin 

 performs from -^ to JL. o f the respiratory function. 



Asphyxia. 



The effects of cutting off the supply of oxygen from the 

 lungs are mainly referable to the circulatory system, and 

 have already been considered under the head of the influence 

 of respiration upon the circulation. 1 It will be remembered 

 that in asphyxia the non-aerated blood passes with so much 

 difficulty through the systemic capillaries, as finally to arrest 

 the action of the heart. It is the experience of those who 

 have experimented on this subject, that the movements of 

 the heart, once arrested in this way, cannot be restored ; but 

 that while the slightest regular movements continue, its 

 functions will gradually return if air be readmitted to the 

 lungs. 



A remarkable power of resisting asphyxia exists in newly 

 born animals that have never breathed. This was noticed by 

 Haller and others, and has been the subject of numerous 

 experiments, among which we may mention those of Buffon, 

 Legallois, and W. F. Edwards. Legallois found that young 

 rabbits would live for fifteen minntes deprived of air by 

 submersion, but that this power of resistance diminished 

 rapidly with age. 2 W. F. Edwards has shown that there 

 exists a great difference in this regard in different classes of 

 animals. Dogs and cats, that are born with the eyes shut, and 

 in which there is at first a very slight development of animal 

 heat, will show signs of life after submersion for more than 

 half an hour ; while Guinea pigs, which are born with the eyes 

 open, are much more active, and produce a greater amount 

 of heat, will not live more than seven minutes. 3 



1 See page 290. a See page 421, note. 



s W. F. EDWARDS, De I } Influence des Agern Physiques sur la Vie, Paris, 1824, 

 pp. 171, 172. 



