812 CHEMISTRY OF RESPIRATION. 



v. SCHROTTER 1 found an average of 37.68 mm. These results do not 

 coincide with the investigations of BoHR, 2 who in many cases obtained 

 essentially higher figures for the oxygen tension in arterial blood. 



He experimented on dogs, allowing the blood, whose coagulation had been 

 prevented by the injection of peptone solution or infusion of the leech, to flow 

 from one bisected carotid to the other, or from the femoral artery to the femoral 

 vein, through an apparatus called by him an h?emataerometer. The apparatus, 

 which is a modification of LUDWIG'S rheometer (stromuhr], allowed, according 

 to BOHR, of a complete interchange between the gases of the blood circulating 

 through the apparatus and a quantity of gas whose composition was known at 

 the beginning of the experiment and inclosed in the apparatus. The mixture 

 of gases was analyzed after an equalization of the gases by diffusion. In this 

 way the tension of the oxygen and carbon dioxide in the circulating arterial blood 

 was determined. During the experiment the composition of the inspired and 

 expired air was also determined, the number of inspirations noted, and the extent 

 of respiratory exchange of gas measured. To be able to make a comparison 

 between the gas tension in the blood and in an expired air whose composition was 

 closer to the unknown composition of the alveolar air than the ordinary expired 

 air, the composition of the expired air at the moment it passed the bifurcation of 

 the trachea was ascertained by special calculation. The tension of the gases in 

 this " bifurcated air " could be compared with the tension of the gases of the blood, 

 and in such a way that the comparison took place simultaneously. Recently 

 KROGH 3 constructed an apparatus, called by him microtonometer, to be used 

 for the same purpose. 



BOHR found remarkably high results for the oxygen tension in arterial 

 blood in this series of experiments. They varied between 101 and 144 

 mm. Hg pressure. In eight out of nine experiments on the breathing 

 of atmospheric air, and in four out of five experiments on breathing air 

 containing carbon dioxide, the oxygen tension in the arterial blood was 

 higher than the " bifurcated air." The greatest difference, where the 

 oxygen tension was higher in the blood than in the air of the lungs, was 

 38 mm. Hg. 



HUFNER and FREDERicQ 4 have made the objection to BOHR'S experi- 

 ments and views that a perfect equilibrium had probably not been 

 attained between the air in the apparatus and the gases of the blood. 

 FREDERICQ, by new experiments, presents strong objections to the 

 acceptance of BOHR'S findings, while on the other hand BOHR not only 

 detends his experiments, but also finds errors in the experiments of his 

 opponents, while HALDANE and SMITH'S 5 experiments, making use of 



1 Strassburg, Pfliiger's Arch., 6; Falloise, Bull. Acad. Roy. Belg., 1902; Wolfberg, 

 Pfliiger's Arch., 4 and 6; Nussbaum, ibid., 7; Loewy and v. Schro'tter, cited by Loewy 

 in Oppenheimer's Handb., 4, 76. 



2 Skand. Arch. f. Physiol., 2, and Nagel's Handbuch der Physiologie. 



3 Skand. Arch. f. Physiol., 20. 



4 Hiifner, Arch. f. (Anat. u.) Physiol. 1890; Fre'dericq, Centralbl. f. Physiol., 7, and 

 Traveaux du laboratorie de Finstitute de physiologie de Liege, 5, 1896. 



5 Haldane, Journ. of Physiol., 18; Haldane and Smith, ibid., 20. 



