upon the Animal System. 19 



long and slow inspirations. Having removed one of these 

 kittens instantly as it fell^ it was restored to life by warmth and 

 artificial respiration. The other, being kept about four minutes 

 under the glass, did not recover by similar means. The blood 

 was uniformly dark, and the circulation still. The lungs were 

 collapsed, and the vessels of the brain contracted. 



Animals immersed in carbonic acid gas appear to be de- 

 stroyed much slower than in other gases uncombined with 

 oxygen, the general difference being between about half a thi- 

 nute and three minutes, the latter being about the average 

 duration of suspended animation from drowning and hanging, 

 in cases of recovery. The cause of death may probably be the 

 same therefore, namely, the want of oxygenated air for the 

 circulation of the brain, for without the red particles of the 

 blood, the cerebral functions cannot go on, and insensibility is 

 directly brought about in animals of hot blood. It is remark- 

 able, that in the experiments with carbonic acid gas, the bodies 

 of the animals were very sensibly elevated in their temperature 

 throughout the whole inside, as if they had been exposed to 

 the influence of a fire. 



In reviewing generally the facts developed in the experi- 

 ments here detailed, it is observable, that all the gases em- 

 ployed are, in fact, perfectly capable of passing the epiglottis, 

 and do, more or less, enter into the circulation through the 

 air-passages of the lungs. And, excepting the carbonic acid 

 gas, each seems to destroy life much in the same manner, and 

 in far less time,^than from the mere exclusion of common air. 

 The phenomena attending the respiration of these gases appa- 

 rently lead to this supposition — that they act upon the prin^ 

 ciple of certain poisonous substances, which are known to 

 suspend the functions of the brain, and quickly destroy sen- 

 sibility, while the organic property of vital contractility survives 

 the animal life in most instances some time after all conscious- 

 ness has ceased. 



The comparison which may be drawn from the experiments 

 upon the oxgenated gases and those without oxygen, while it 

 shows the first to be ultimately destructive to sensibility, though 

 tending to prolong animal life to a degree far beyond any other 

 gases, displays the relations of oxygen to animal life in a very 

 striking point of view. This comparison suggests also some 



C2 



