278 THE BLOOD. 



by v. ZEYNEK. 1 It is immediately formed in the cold by the action of a hydro- 

 cyanic-acid solution upon methaBmoglobin, but is formed by its action upon 

 oxy haemoglobin only at the body temperature. The neutral or faintly alkaline 

 solutions show a spectrum which is very similar to the haemoglobin spectrum. 

 Acid haemoglobin is a coloring-matter produced by the action of very weak 

 acids upon oxyhsemoglobin, which according to HARNACK 2 is not, as used to be 

 admitted, identical with methaemoglobin. 



Carbon-monoxide Haemoglobin 3 is the molecular combination between 

 1 molecule of haemoglobin and 1 molecule of CO, according to HuFNER, 4 

 which contains 1.34 cc. of carbon monoxide (at and 760 mm. Hg) 

 for 1 gram haemoglobin. This combination is stronger than the oxygen 

 combination of haemoglobin. The oxygen is for this reason easily driven 

 out of oxyhaemoglobin by carbon monoxide, and this explains the poison- 

 ous action of this gas, which kills by the expulsion of the oxygen of the 

 blood. In regard to the division of the blood-pigments between the car- 

 bon monoxide and oxygen under different partial pressures of both gases 

 in the air, we must refer to the investigations of HUFNER, 5 whose results 

 are tabulated. 



The carbon monoxide can be driven out by a vacuum as well as by 

 passing an indifferent gas or oxygen or nitric oxide through the solution 

 for a long time, and in these cases haemoglobin, oxyhaemoglobin, or 

 nitric-oxide haemoglobin are formed. The carbon monoxide is also 

 expelled by potassium ferricyanide and methaemoglobin is formed 

 (HALDANE 6 ). 



Carbon-monoxide haemoglobin is formed by saturating blood or a 

 haemoglobin solution with carbon monoxide, and may be obtained as 

 crystals by the same means as oxyhaemoglobin. These crystals are iso- 

 morphous with the oxyhaemoglobin crystals, but are less soluble and more 

 stable, and their bluish-red color is more marked. For the detection 

 of carbon-monoxide haemoglobin, its absorption-spectrum is of the greatest 

 importance. This spectrum shows two bands which are very similar 

 to those of oxyhaemoglobin, but they occur more toward the violet 



1 Haldane, Journ. of Physiol., 25; Bock, Skand. Arch. f. Physiol., 6; Robert, 

 Pfliiger's Arch., 82; v. Zeynek, Zeitschr. f . physiol. Chem., 33. See also Leers, Biochem. 

 Zeitschr., 12. 



2 Zeitschr. f . physiol. Chem., 26. 



3 In reference to carbon-monoxide haemoglobin, see especially Hoppe-Seyler, Med.- 

 chem. Untersuch., 201; Centralbl. f. d. med. Wissensch., 1864 and 1865; Zeitschr. 

 f. physiol. Chem., 1 and 13. 



4 Arch. f. (Anat. u.) Physiol., 1894. On the dissociation constant of carbon- 

 monoxide haemoglobin, see ibid., 1895. In regard to the contradictory statements of 

 Saint-Martin and others and their disapproval, see Hiifner, Arch, f . (Anat. u.) Physiol., 

 1903. 



3 Arch. f. exp. Path. u. Phann., 48. 

 8 Journ. of Physiol., 22. 



