OXYGEN TENSION IN BLOOD. 861 



globin in the arterial blood that the tension of the oxygen in the arterial 

 blood must be relatively higher. This is substantiated' by the earlier 

 observations of BERT and HUFNER, as well as by the determinations 

 of HERTER, FREDERICQ and others, 1 using aerotonometric methods, 

 which will be mentioned below in connection with the carbon dioxide 

 tension. HERTER found the oxygen tension in the arterial blood of 

 dogs to be equal, on an average, to a pressure of 78.7 mm. Hg and FRE- 

 DERICQ, by a better method, found that it was equal to 91-99 mm. Hg. 



The oxygen tension of the venous blood of dogs has been found by 

 aerotonometric means to be equal to 20.6-27.7 mm. (STRASSBURG, 

 FALLOISE), and by means of the lung-catheter (see below) equal to 25.5-27 

 mm. (WOLFBERG, NUSSBAUM). For human venous blood LOEWY and v. 

 ScHROTTER 2 found an average of 37.68 mm. Concerning the question 

 as to the mechanism of taking up oxygen in the lungs these figures are of 

 less interest than the oxygen tension in the arterial blood, that is, that 

 which has left the lungs, whose tension is estimated as 90 to about 100 

 mm. Hg as given above. 



These results do not coincide with the investigations of BOHR, S who 

 in many cases obtained essentially higher figures for the oxygen tension 

 in arterial blood. 



fle 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 hsemataerometer. 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 



1 Bert, La pression barometrique, Paris, 1878; Herter, Zeitschr. f. physiol. Chem. 

 3; Hiifner, 1. c.; Fredericq, Centralbl. f. Physiol., 7, and Travaux der laborat. de 

 1'inst. de physiol. de Liege, 5, 1896. 



2 Strassburg, Pfliiger's Arch., 6; Falloiso, Bull. Acad. Roy. Belg., 1902. Wolfberg, 

 Pfliiger's Arch., 4 and 6; Nussbaum, ibid., '/; Loewy and v. Schrotter, cited by Loewy 

 in Oppenheimer's Handb., 4, 76. 



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



