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866 RESPIRATION AND OXIDATION.
place. The method of catheterizing the lungs is, as shown by Loewy
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,3
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.
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