H^EMOCHROMOGEN. 281 



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

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

 haBmatin, and 1.44 per cent other bodies are produced in this decomposi- 

 tion. 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 coag- 

 ulum is readily soluble in acids. Because of these reactions it is con- 

 sidered as a hist one by SCHULZ. 



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

 to AiiDERHALDEN, 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 hoemochromogen, by other investigators (STOKES) 

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

 oxidized to haBmatin, and there is therefore obtained in this case hoe-matin 

 as a colored decomposition product. As haBmochromogen is easily 

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

 into haBmochromogen 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 haBmochromogen, and it is also this atomic group which binds in 

 the oxyhaBmoglobin 1 molecule of oxygen and in the carbon-monoxide 

 hemoglobin 1 molecule of carbon monoxide with 1 atom of iron. HaBmo- 

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

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

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

 brownish-red ammonia combination. 



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

 carbon monoxide. This compound, which in aqueous solution gives 

 a spectrum similar to oxyhaBmoglobin, has been obtained by PREGL 5 in 



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. 5 Ibid., 44. 



