x METH.EMOGLOBIN 491 



the latter more acid according to Kiihne ; in methaemoglobin, which 

 shows different spectra according as to whether it is in an acid or in 

 an alkaline solution, a current of hydrogen acts like an alkali (? by 

 carrying off C0 2 ), while oxygen acts like an acid, according to Jader- 

 holm. Mention must also be made of Hoppe-Seyler's l observation 

 that oxy haemoglobin is converted into reduced haemoglobin on being 

 gently warmed with ammonia. These investigations deserve to be 

 repeated in the light of our present knowledge regarding the migration 

 of radicals in a molecule (see below). In coagulating haemoglobin 

 by heat and so denaturalising it, the larger amount of oxygen and 

 other gases present remain in the coagulum according to Hermann and 

 Steger; 2 similarly when oxyhaemoglobin is dissociated into globin. 

 and haematin, oxygen is bound up. 



Methaemoglobin 



That oxy haemoglobin readily changes into a new compound of 

 a brownish colour which possesses in addition to the bands of oxy- 

 haemoglobin an additional band in the red end of the spectrum was 

 first observed by Hoppe-Seyler, 3 who called this new substance 

 methaemoglobin. He was of the opinion that it resulted from a 

 partial reduction of oxyhaemoglobin, a view we now know to be 

 wrong. Gamgee 4 then showed that nitrites, including amyl-nitrite, 

 nitroglycerine, etc., were especially apt to give rise to methaemoglobin * r 

 and that methaemoglobin holds the oxygen so firmly that the latter 

 cannot be removed by boiling in vacua or by the action of carbonic 

 oxide, but that reducing agents instantly convert methaemoglobin into 

 oxyhaemoglobin, which latter then by the continued action of the 

 reducing substances is converted into reduced haemoglobin See,, 

 however, Haldane's view regarding the last point, on p. 493. 



Oxyhaemoglobin is so readily converted into methaemoglobin, that 

 if it be kept without special precautionary measures having been 

 taken, part of it becomes changed into methaemoglobin. It seems 

 likely that the diminution in the power of oxygen-dissociation which 

 ensues if alcohol be used for the preparation of oxyhaemoglobin 

 crystals is already the first step towards the formation of met- 

 haemoglobin ; the latter is further formed by the action of a great 



1 F. Hoppe-Seyler, Zentralbl.f. d. med. Wissenschaften, 1864, p. 817. 



2 L. Hermann and Th. Steger, Pfluger's Arch. /. d. ges. Physiol. 1O. 86 (1875). 



3 F. Hoppe-Seyler, ZentralU. f. d. med. Wissenschaften, 1864, No. 53, and 1865. 

 p. 65. See also Med. chem. Untersuch. Berlin, p. 378, and Zeitschr. f. physiol. Chem., 

 2. 150, 155 (1878). 



4 A. Gamgee, Fhilosoph. Trans. 158. I. 159 and 589 (1868). 



