ANALYSIS OF THE BLOOD FOE GASES. 461 



taken into the lungs, it is absorbed by and becomes fixed in 

 the corpuscles, effectually preventing the consumption of oxy- 

 gen and production of carbonic acid, which normally takes 

 place in the capillary system, and which is one of the indis- 

 pensable conditions of nutrition. We have already referred 

 to the mechanism of poisoning by the inhalation of this gas, 

 by its fixation in the blood-corpuscles, their consequent par- 

 alysis, and the arrest of their function as respiratory organs. 

 As it is the continuance of this transformation of oxygen into 

 carbonic acid, after the blood is drawn from the vessels, which 

 interferes with the ordinary analysis of the blood for gases, 

 we might expect to extract all the oxygen, if we could imme- 

 diately saturate the blood with carbonic oxide. The prelim- 

 inary experiments of Bernard on this point are conclusive. 

 He ascertained that by mixing carbonic oxide in sufficient 

 quantity with a specimen of fresh arterial blood, in about 

 two hours, all the oxygen which it contained was dis- 

 placed. Introducing a second quantity of carbonic oxide af- 

 ter two hours, and leaving it in contact with the blood for an 

 hour, a quantity of oxygen was removed, so small that it 

 might almost be disregarded. A third experiment on the 

 same blood failed to disengage any oxygen or carbonic acid. 1 



The view entertained by Bernard of the action of car- 

 bonic oxide in displacing the oxygen of the blood is, that the 

 former gas has a remarkable affinity for the blood-corpuscles, 

 in which nearly all the oxygen is contained, and when 

 brought in contact with them unites with the organic matter, 

 setting free the oxygen, in the same w r ay that the acid enter- 

 ing into the composition of a salt is set free by any other 

 acid which has a stronger affinity for the base. There is 

 every reason to suppose that this view is correct ; as carbonic 

 oxide is much less soluble than oxygen, and as it only has the 

 property of disengaging this gas from the blood, leaving the 

 other gases still in solution. 



As carbonic oxide only displaces the oxygen, it is neces- 



1 BERNARD, Liquidcs de VOrganisme, tome i., p. 373. 



