MELANIN 475 



occurs in dark-coated horses, has not been explained. The frequent 

 occurrence of mehmuria and mehincniia in patients witli iiiolanosar- 

 coma is not duo to any peculiar property of sarcoma nichmin, but to 

 the enormous quantity of melanin that is prochKuul by the tumor and 

 set free in the degenerating; portions. Thus, while Abel and Davis'^ 

 estimate that there is only about 1 gram of melanin in the entire skin 

 of a negro, Nencki and Bordez have obtained from a sarc-omatous 

 liver 300 grams of melanin, and estimate that the entire body con- 

 tained 500 grams. Helman'^ states that the melanin may con- 

 stitute 7.3 per cent, by weight of the fresh substance of some 

 melanosarcomas. According to Lubarsch and to Helman, melanotic 

 tumors rarely contain glycogen. 



As mentioned above, Neubcrg found that a melanotic sarcoma of 

 the adrenal produced pigment from epinephrin and from /3-oxy- 

 phcnylethylamine, but he failed to get positive results with melano- 

 sarcomas of the eye and from the horse, but Alsberg-' succeeded in 

 finding in melanosarcoma from the liver an enzyme oxidizing pyro- 

 catechin and Jager- found that horse melanosarcoma extracts will 

 oxidize epinephrin to a pigment. The "dopa reaction" of Bloch,^^ 

 which depends on the presence of specific oxidizing enzymes in the 

 cells, may be exhibited by the connective tissues quite generally 

 throughout the body in some cases of melanosarcoma."" 



Eppinger-^ found that the urine of a patient with melanosarcoma 

 gave intense reactions for indole and tryptophane, and that when 

 tryptophane was fed to a patient there was a great increase in the 

 melanuria. He therefore concludes that the power of the body to 

 destroy the pyrrole ring is reduced, and instead it undergoes reduc- 

 tion, methylation and union with sulphuric acid, to form an ethereal 

 sulphate of methylpyrrolidine-hydroxy-carbonic acid (CH3-C5H9N2O4). 

 Abderhalden-'' also found a relation to tryptophane, for in the urine 

 of a melanuric was present a substance rich in tryptophane; and 

 Primavera" found the urine in a case of melanosarcoma containing 

 free tyrosine, fluctuating in amount with the pigment. 



Addison's disease is associated with the deposition of a pigment 

 in the skin that is generally considered to be a melanin, differing 

 from that produced normally in the skin only in quantity and not in 

 origin or composition. ^"^ No satisfactory explanation of the relation 

 of the adrenal to this pigmentation seems yet to have been made, al- 

 though it is natural to assume that when the function of the adrenal 

 is destroyed, substances accumulate in the blood that have a stimu- 

 li Jour. Med. Res., 1907 (16), 117. 



22 Virchow's Arch., 1909 (198), 62. 



•"" Matsunaga, Frankf. Zeit. Path., 1919 (22), 69. 



" Biochem. Zeit., 1910 (28 j, 181. 



2^ Zeit. physiol. Chem., 1912 (78), 159. 



" Giorn. Int. Scienze Med., 1908 (29), 978. 



-« Concerning histogenesis of the pigment see Pforringer, Cent. f. Path., 1900 

 (11), 1. 



