THE FORMATION OF MELANINS OR MELANIN- 

 LIKE PIGMENTS FROM PROTEID SUBSTANCES.* 



BY R. H. CHITTENDEN AND ALICE H. ALBBO. 



THE brownish black animal pigments, collectively known as 

 melanins, occurring normally and pathologically in the body, 

 are characterized as a class by a somewhat high content of 

 carbon, a relatively low content of nitrogen, and a variable, 

 though usually high, percentage of sulphur. The presence of 

 the latter element in very appreciable amounts constitutes one 

 of the reasons for the belief that these substances have their 

 origin in some proteid antecedent, while the absence of iron, in 

 most cases, excludes the view that they originate from the 

 blood pigment. In a recent contribution by Schmiedeberg f 

 to the chemical composition and nature of melanins, emphasis 

 is laid upon the possible origin of these substances in antial- 

 bumid. This view is seemingly based upon the partial resem- 

 blance in chemical composition between the latter substance 

 and the melanins, a resemblance which is indeed somewhat 

 striking. As a cleavage product of the proteids, antialbumid 

 is characterized by a comparatively high content of carbon and 

 a low content of nitrogen, and Schmiedeberg concludes that 

 melanin may result from antialbumid by a process of hydrolytic 

 cleavage comparable to the method by which the latter body 

 results from albumin itself. He further points out that the 

 sulphur of the antialbumid may remain with the melanin, thus 

 accounting for the large amount of this element usually found, 

 while ammonia and water are split off according to the follow- 

 ing equation: 



C 120 H 187 N 27 S0 87 = C lao H 114 N 8 S0 29 + 19NH, + 8H 2 0. 

 Antialbumid. Melanin. 



Reprinted from the Amer. Jour, of Physiol., vol. ii. 

 t Schmiedeberg, Archir f. Exper. Pathol. u. Pharmakol., 1897, zzxiz, 

 p. 66. 



