Abstract
Some authors believe that melanin are responsible for occasional black appearance of g _??_ llstones and for brown pigmentation of the liver in the case of Dubin-Johnson syndrome. However, it should be doubtful if melanins are real-ly produced in the hepato-biliary system which is known to be devoid of melanophores in the normal condition. To dissolve the problem, black pigments were isolated from black-appearing gallstones and were chemically and physico-chemically compared with native and synthetic melanins. Although the gallstone pigments resembled melanins in general properties, a definite difference could be pointed out between both kinds of pigments in the infrared absorption spectra, indicating a probable difference in the structure of these substances.
