HSEMOCHROMOGEN. 289 



called globin (PREYER, SCHULZ), and a ferruginous pigment as chief prod- 

 ucts. According to LAWROW 94.09 per cent protein, 4.47 per cent 

 hsematin, and 1.44 per cent other bodies are produced in this decom- 

 position. The globin, which was isolated and studied by SCHULZ/ 

 differs from most other proteins by containing a high amount of carbon, 

 54.97 per cent., with 16.98 per cent of nitrogen. It is insoluble in water, 

 but very easily soluble in acids or alkalies. It is not dissolved by ammonia 

 in the presence of ammonium chloride. Nitric acid precipitates it in 

 the cold, but not when warm. It may be coagulated by heat, but the 

 coagulum is readily soluble in acids. Because of these reactions it is 

 considered as a histone by SCHULZ. 



On hydrolytic cleavage globin (from horse-blood) yields, accord- 

 ing to AEDERHALDEN, 2 the ordinary cleavage products of the proteins 

 and especially leucine, 29 per cent. It is also important to call attention 

 to. the large amount of histidine, 10.96 per cent, while the quantities of 

 arginine and lysine were only 5.42 and 4.28 per cent respectively. 



The pigment split off is different, depending upon the conditions 

 under which the cleavage' takes place. If the decomposition takes place 

 in the absence of oxygen, a coloring-matter is obtained which is called 

 by HOPPE-SEYLER hcemochromogen, by other investigators (STOKES) 

 reduced hcematin. . In the presence of oxygen, hsemochromogen is quickly 

 oxidized to hsematin, and there is therefore obtained in this case hcematin 

 as a colored decomposition product. As hsemochromogen is easily 

 converted by oxygen into hsematin, so this latter may be reconverted 

 into hsemochromogen by reducing substances. 



Haemochromogen was discovered by HOPPE-SEYLER. S It is, accord- 

 ing to HOPPE-SEYLER, the colored atomic group of haemoglobin and of 

 its combinations with gases, and this atomic group is combined with 

 proteins in the pigment. The characteristic absorption of light depends 

 on the hsemochromogen, and it is also this atomic group which binds, in 

 the oxyhsemoglobin, 1 molecule of oxygen and, in the carbon-monoxide 

 hsemoglobin, 1 molecule of carbon monoxide with 1 atom of iron. Hsemo- 

 chromogen is produced in an alkaline solution of hsematin by the action 

 of reducing bodies. By the reduction of hsematin in alcoholic ammoniacal 

 solution by means of hydrazine v. ZEYNEK 4 was able to obtain the solid 

 brownish-red ammonia combination. A crystalline combination between 

 pyridine and hsemochromogen can be obtained according to KALMUS 



1 Lawrow, ibid., 26; Schulz, ibid., 24; Preyer, Die Blutkristalle, Jena, 1871. 



2 Zeitschr. f. physiol. Chem., 37; with Baumann, ibid., 51. 



3 Ibid., 13. 



4 Zeitschr. f. physiol., Chem., 25. 



