286 THE BLOOD. 



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

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

 The question as to a special cyanmethsemoglobin is still disputed. 



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

 acids upon oxyhsemoglobin, which according to HARNACK 1 is not, as used to be 

 admitted, identical with methffimoglobin. 



Carbon-monoxide Haemoglobin 2 is the molecular combination between 



1 molecule of haemoglobin and 1 molecule of CO, according to HtJFNER, 3 

 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 oxyhsemoglobin 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, DOUGLAS and 



HALDANE. 4 



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 solu- 

 tion 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 5 ) . The above-mentioned behavior found by MANCHOT for 

 the absorption of oxygen, namely, that the amount of gas taken up 

 increases with the dilution of the blood so that for every atom of iron 



2 mol. of gas are absorbed applies also for the carbon-monoxide haemo- 

 globin as well as for the nitric-oxide haemoglobin, which will be discussed 

 further on. 



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 

 isomorphous with the oxyhaemoglobin crystals, but are less soluble and 

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



1 Zeitschr. f. physiol. Chem., 26. 



2 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. 



3 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. 



4 Hiifner, Arch. f. exp. Path. u. Pharm., 48; Douglas and Haldane, Journ. of 

 Physiol., 44. 



5 Journ. of Physiol., 22. 



