290 THE BLOOD. 



and v. ZEYNEK 1 from haemoglobin and pyridine by boiling, or from 

 hsematin and hsemin and pyridine after the addition of hydrazin-hydrate. 



Haemochromogen also combines, as HOPPE-SEYLER first showed, with 

 carbon monoxide. This compound, which in aqueous solution gives 

 a spectrum similar to oxyhaemoglobin, has been obtained by PREGL 2 

 in the solid condition as a deep-violet powder which is insoluble in 

 absolute alcohol. In opposition to haemoglobin the hsemochromogen 

 combines with oxygen more firmly than with carbon monoxide. The 

 assumption of HOPPE-SEYLER, that this compound is a combination of 1 

 molecule hsemochromogen and therefore contains 1 molecule carbon 

 monoxide for 1 molecule of iron has been experimentally substantiated 

 by HUFNER and KUSTER and by PREGL. 3 



An alkaline haemochromogen solution has a beautiful cherry-red 

 color. It shows two absorption-bands, first described by STOKES (spec- 

 trum Plate, 6), one of which is dark and whose center corresponds to 

 X = 556.4 between D and E, and a second broader band, less dark, which 

 covers the FRAUNHOFER lines E and b. The middle of this band cor- 

 responds to X = 526 to 530 according to LEWIN, MIETHE and STENGER. 

 In acid solution haemochromogen shows four bands, which, according 

 to JA.DERHOLM, 4 depend on a mixture of hsemochromogen and haemato- 

 porphyrin (see below), this last formed by a partial decomposition 

 resulting from the action of the acid. 



MiLROY, 5 from an alcoholic solution of haematin containing oxalic 

 acid, after driving out the air by means of hydrogen gas, gradually obtained 

 an acid solution of reduced haematin (hsemochromogen) by means of 

 zinc dust. This solution showed one absorption-band between D and E. 



Haemochromogen may be obtained as crystals by the action of caustic 

 soda on haemoglobin at 100 C. in the absence of oxygen (HOPPE-SEYLER). 

 By the decomposition of haemoglobin by acids (of course in the absence 

 of air) we obtain hsemochromogen contaminated with a little haemato- 

 porphyrin. An alkaline haemochromogen solution is easily obtained by 

 the action of a reducing substance (STOKES' reduction liquid) on an 

 alkaline haematin solution. An ammoniacal solution of haematin on 

 reduction with hydrazine yields haemochromogen very easily. An alco- 

 holic, alkaline hydrazine solution is also recommended by RIEGLER 6 

 as a reagent for blood-pigments, converting them into hsemochromogen. 



Haematin, also called OXYH^EMATIN, is sometimes found in old transu- 

 dates. It is formed by the action of the gastric or pancreatic juices on 



1 E. Kalmus, Zeitschr. f. Chem., 70; v. Zeynek, ibid., 70. 



2 Ibid., 44. 



3 Hufner and Kuster, Arch. f. (Anat. u.) PhysioL, 1904, Suppl. Pregl, 1. c. 



4 Nord. Med. Arkiv., 16. 

 6 Journ. of Physiol., 32. 



6 Zeitschr. f. anal. Chem., 43. 



