284 THE BLOOD. 



nitrobenzene, pyrogallol, pyrocatechin, acetanilide, and certain other 

 bodies on the blood an abundant formation of methsemoglobin takes place. 

 By the action of light, HASSELBACH, 1 especially by the use of rays hav- 

 ing a wave-light below 310 M M, obtained methsemoglobin from oxyhsemo- 

 globin, but not from haemoglobin in the absence of oxygen, and by this 

 behavior pure methsemoglobin can be prepared. 



According to the investigations of HUFNER, KULZ, and OTTO 2 

 methsemoglobin contains just as much oxygen as oxy haemoglobin, but 

 it is more strongly combined, a view which is accepted by most investiga- 

 tors. According to HUFNER and v. ZEYNEK we can admit in the methsemo- 

 globin formation of an expulsion of oxygen and a combination of two 



/OR 

 hydroxyl groups; methsemoglobin would then be Hb<^ . Accord- 



[b^ . 



N OH 



ing to others, HOPPE-SEYLER, KUSTER, LETSCH the methsemoglobin 

 contains less oxygen than the oxyhsemoglobin and is HbO or HbOH. 

 A methsemoglobin solution is converted into a hsemoglobin solution 

 by reducing substances. The reaction taking place in the forma- 

 tion of methsemoglobin from oxyhsemoglobin by the action of potassium 

 ferricyanide has been quantitatively followed by v. REiNBOLD. 3 He 

 found that one molecule of KsFe(CN)6 was necessary to transform 1 

 molecule oxyhsemoglobin or to drive off 1 molecule of oxygen from the 

 oxyhsemoglobin. The reaction takes place according to the equation: 



/O 



Hb< | ^K3Fe(CN)6+H20 = Hb.OH+K 3 HFe(CN)6+02 

 X) 



and from his investigations he gives the formula Hb.OH to methsemo- 

 globin, in correspondence to the views of KUSTER. 



According to HUFNER and REINBOLD 4 1 gram methsemoglobin can 

 take up 2.685 cc. nitric oxide. 



Methsemoglobin crystallizes, as first shown by HUFNER and OTTO, 

 in brownish-red needles, prisms, or six-sided plates. It dissolves easily 

 in water; the solution has a brown color and becomes a beautiful red 

 on the addition of alkali. The solution of the pure substance is not 

 precipitated by basic lead acetate alone, but by basic lead acetate and 



. Zeitschr., 19. 



2 See Otto, Zeitschr. f. physiol. Chem., 7; v. Zeynek, Arch. f. (Anat. u.) Physiol., 

 1899; Hiifner, ibid. 



3 Kiister, Zeitschr. f. physiol. Chem., 66; Letsche, ibid., 80; v. Reinbold, Zeitschr. 

 f. physiol. Chem., 85. 



4 Arch, f . (Anat. u.) Physiol., 1904, Suppl. 



