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852 RESPIRATION AND OXIDATION.
Oxygen is dissolved only in a small extent by the plasma, whose
absorbability for oxygen is 97.5 per cent of that of water, according to
Bohr. The greater part or nearly all of the oxygen is loosely combined
with the haemoglobin. The quantity of the oxygen which is contained in
the blood of the dog corresponds closely to the quantity which, from the
activity of the haemoglobin, we should expect to combine with oxygen
and from the quantity of haemoglobin contained therein. It is difficult
to ascertain how far the circulating arterial blood is saturated with oxygen,
as immediately after bleeding a loss of oxygen always takes place. Still
it seems to be unquestionable that it is not quite completely saturated
with oxygen, in life. The laws which regulate the binding of the oxygen
in the blood will be found in the discussion of the gas exchanged between
the blood and the air of the lungs.
The carbon dioxide of the blood occurs in part, and indeed, accord-
ing to the investigations of Alex. Schmidt,1
Zuntz,2
and L. Fredericq,3
to the extent of at least one-third in the blood-corpuscles, also in part,
and in fact the greatest part, in the plasma or serum. Bohr 4
claims
that about 30 mm. may be considered as the average pressure of the
carbon dioxide in the organism, and with such a pressure the quantity of
physically dissolved CO2 in 100 cc. of the blood amounts to 2.01 cc. As
the blood with this tension takes up about 40 vols, per cent CO2, there-
fore about 5 per cent of the total carbon dioxide is simply dissolved.
Under the assumption that the blood corpuscles make up about one-
third of the volume of the blood, of the physically dissolved CO2, 0.59
cc. exists with the corpuscles and 1.42 cc. with the plasma.
As the blood corpuscles in 100 cc. blood as above stated take up at
the above pressure about 14 cc. CO2, only a small part of its CO2 is physi-
cally dissolved. The chief mass of the CO2 is loosely combined and the
constituent of these cells which unites with the CO2 seems to be the
alkali combined with phosphoric acid, oxyhemoglobin or haemoglobin,
and globulin on one side and the haemoglobin itself on the other. That
in the red blood-corpuscles alkali phosphate occurs in such quantities
that it may be of importance in the combination with carbon dioxide
is not to be doubted ; and it must be allowed that from the diphosphate,
by a greater partial pressure of the carbon dioxide, monophosphate and
alkali carbonate are formed, while by a lower partial pressure of the
carbon dioxide, the mass action of the phosphoric acid again comes into
play, so that, with the carbon dioxide becoming free, a reformation of
1
Ber. d. k. sachs. Gesellsch. d. Wissensoh. math.-phys. Klasse, 1867.
•Centralbl. f. d. med. Wissensch., 1867, 529.
3
Recherches sur la constitution du Plasma sanguin, 1878, 50, 51.
4
In regard to the work of Bohr we will refer here and in future to Nagel’s Handbuch
der Physiologje des Menschen, Bd. 1.
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