866 RESPIRATION AND OXIDATION. 



place. The method of catheter! zing the lungs is, as shown by LOEWT 

 and v. ScHROTTER, 1 also applicable to man, and they found that the 

 carbon dioxide tension of human venous blood was equal to 6 per cent 

 of the atmospheric pressure in the lungs = 42.6 mm. Hg, while according 

 to LOEWY'S calculations the carbon dioxide tension in the respired lung 

 aveoli varied between 31.8 and 41.8 mm. Hg with an average of 37.3 

 mm. Hg for eleven cases. 



According to these investigations the giving up of carbon dioxide 

 may also be explained by physical laws; but BOHR, in his experiments 

 above mentioned (page 861), has arrived at other results in regard to 

 the carbon-dioxide tension. In eleven experiments with inhalation of 

 atmospheric air the carbon-dioxide tension in the arterial blood varied 

 from to 38 mm. Hg, and in five experiments with inhalation of air con- 

 taining carbon dioxide, from 0.9 to 57.8 mm. Hg. A comparison of the 

 carbon-dioxide tension in the blood with the bifurcated air gave in several 

 cases a greater carbon-dioxide pressure in the air of the lungs than in 

 the blood, and as maximum this difference amounted to 17.2 mm. in 

 favor of the air of the lungs in the experiments with inhalation of atmos- 

 pheric air. As the aveolar air is richer in carbon dioxide than the bifur- 

 cated air this experiment unquestionably proves, according to BOHR, 

 that the carbon dioxide has migrated against the high pressure. 



In opposition to these investigations, FREDERicQ, 2 in his above-men- 

 tioned experiments, obtained the same figures for the carbon-dioxide 

 tension in arterial peptone blood as PFLUGER and his pupils found for 

 normal blood. WEISGERBER, S in FREDERICQ'S laboratory, has made 

 experiments with animals which respired air rich in carbon dioxide, and 

 these experiments confirm PFLUGER'S theory of respiration. Recently 

 FALLOISE has made determinations of the carbon-dioxide tension of 

 venous blood by means of FREDERICQ'S aerotonometer. The carbon- 

 dioxide tension was found to equal 6 per cent of an atmosphere, hence 

 somewhat higher than the results found by PFLUGER'S pupils. To these 

 investigations BOHR has presented strong objections; he has demon- 

 strated the principles for the construction of the tonometer, and claims that 

 the earlier experiments with the tonometer are not conclusive, as a 

 complete equilibrium of the gas tension was not attained. 



A certain importance has been ascribed to oxygen in regard to the 

 elimination of carbon dioxide in the lungs, in that it has an expelling 

 action on the carbon dioxide from its combinations in the blood. This 

 theory, first advanced by HOLMGREN, has recently found an advocate 



1 1. c., footnote 2, page 861. 



2 See footnote 1, page 861. 



Centralbl. f. Physiol., 10, 482; Falloise, see Maly's Jahresber., 32. 



