BLOOD AND LYMPH. 563 



It is highly probable that hemoglobin not only occurs in the red blood- 

 corpuscles, but in the muscles as well. The latter likewise contain a red 

 pigment which cannot be washed out by way of the vascular system, and 

 which, according to its entire behavior, is certainly closely related to 

 hemoglobin. The relation of this pigment to hemoglobin has never been 

 satisfactorily explained. 



Hemoglobin is decomposed by gentle attack into its two components, 

 globin and hemochromogen. The separation can be effected, for ex- 

 ample, by adding a few drops of dilute acid to a hemoglobin solution which 

 is free from salts. Acid hemoglobin is formed as an intermediate product. 

 It shows an absorption spectrum similar to that of methemoglobin. By 

 more energetic action of the acid, hemochromogen is split off, but only 

 when the solution is kept out of contact with the air. In the presence 

 of air, hematin is always formed; from the latter, by reduction, hemo- 

 chromogen may be obtained. The digestive juices of the stomach and 

 pancreas are also capable of effecting this separation of hemoglobin into 

 its two constituents. 



Hematin, whose reduction product, hemochromogen, plays such an 

 important part in allowing the blood to combine with oxygen, has been 

 carefully studied in recent years. Although its constitution has not been 

 established positively, still we are now able to explain certain relations 

 existing between it and other compounds of similar construction. The 

 most important work in this field has been that of Nencki 1 and that of 

 William Kiister. 2 According to Kuster, the empirical formula of hema- 

 tin is C34H 3 4N4FeO 5 . Nencki and Sieber assume its formula to be 

 Cs2H32N4FeO4. The starting-point of these investigations was not 

 usually hematin itself, but its hydrochloric acid ester, hemin, or Teich- 

 mann's crystals as it is sometimes called. Several different formulae 

 have been proposed for this ester. 



It is questionable whether hemin is actually to be regarded as the 

 hydrochloric acid ester of hematin. Nencki in his work stated that 

 it was not formed by merely annexing the hydrochloric acid to the 

 hematin molecule, but that there was a replacement of an OH group by 

 chlorine : 



3 + H 2 O. 

 Hematin Hemin 



1 Nencki and Sieber: Arch, exper. Path. Pharm. 24, 430 (1888), and Monatsh. 9, 

 115 (1888). Nencki and Rotschy: ibid. 10, 568 (1889). Nencki and Zaleski: Z. 

 physiol. Chem. 30, 384 (1900); Ber. 34, 997 (1901). 



2 Ber. 27, 572 (1894); 29, 821 (1896); 30, 105 (1897); Z. physiol. Chem. 28, 1 

 (1899); 29, 185 (1900); Ber. 32, 678 (1899); 33, 3021 (1900); 36, 1268, 2948 

 (1902) ; Ann. 315, 174 (1900). Z. physiol. Chem. 44, 391 (1905) ; Ann. 345, 1 

 (1906). 



