CHEMICAL PHENOMENA OF RESPIRATION. 327 



the blood passes through the vessels of the lung, owing to the 

 expansion of the latter ; while others hold that its function is 

 entirely physical, and consists in cooling the blood by contact 

 with the air. This cooling does take place, as we have said, 

 but i t is a secondary process, and of scarcely any importance 

 (Cl. Bernard). Only a small proportion of the cold air which 

 enters the respiratory tree at each respiration penetrates as 

 far as the pulmonary lobules, and that only after it has been 

 warmed. The larger part of the air inhaled is confined to 

 the respiratory organs, the nasal chambers, the pharynx, and 

 the large bronchi. Lavoisier was the first to furnish any 

 certain knowledge as to the process of respiration ; confirm- 

 ing the ideas entertained by J. Mayow, 1 in regard to his 

 spritus igno-aereus. Lavoisier showed that respiration was a 

 process of combustion, but did not, however, determine the 

 exact seat of the combustion: Lagrange, Spallanzani, and 

 William Edwards proved that these oxidations take place 

 in the tissues, and that the lungs are only the place from 

 which the gaseous products of these interior combustions are 

 exhaled. 



It is not, however, sufficient to know that the blood in the 

 lungs simply evolves carbonic acid, and imbibes oxygen ; the 

 necessary conditions of this interchange must be distinctly 

 stated. First, in regard to the oxygen, we already know 

 that this gas is not dissolved by the blood, but is absorbed 

 by the red globules (Hematocrystalline). Neither is the 

 exhalation of the carbonic acid produced, as might be at first 

 supposed, simply by a diffusion of the gas, or by the evolution 

 of dissolved gas in an atmosphere containing very little of 

 the gas. The air of the pulmonary vesicles contains actually 

 8 per cent of CO' 2 , which is a condition unfavorable to the 

 evolution of the carbonic acid of the blood ; while, on the 

 other hand, a portion of the latter is, not dissolved, but com- 

 bined with the salts of the serum (carbonates and phosphates. 

 Emile Fernet. See p. 129). It is, therefore, probable, that 

 some process takes place in the lungs, the effect of which is 

 to forcibly expel the carbonic acid; this process is undoubt- 

 edly chemical in its nature, and some experiments seem to 

 show that it somewhat resembles that, by means of which 

 the acids evolve carbonic acid from the carbonates. These 

 facts gave rise to the theory formed by Robin and Verdeil as 



1 See Gavarret, " Les Phenomenes Physiques de la Vie." 

 Paris, 1869. 



