MEIvAN^MIA. BLACK PIGMENT IN BLOOD. 



Definition. Melanin, in normal tissues, abnormal. Melanosis. Bisul- 

 phide of carbon subcutem. Decomposition of hsenioglobin in leucocytes. 

 Coloration of tissue. 



Definition. Accumulation of granules and .scales of blood pig- 

 ment (melanin) in the circulating fluid, and in various organs 

 (spleen, liver, bone marrow, brain, etc). 



Melanin — C„. 2, H3, Ny.g, O.^.g — or black pigment (a close rela- 

 ative of haematin) occurs physiologically in epithelium (choroid, 

 retina, iris, in the deeper layers of epidermis, and on the surface 

 of the dog's lung and of the sheep's brain) and in connective tis- 

 sue corpuscles (lamina fusca of the choroid). 



Pathologically it is found in the blood of the victims of malarious 

 fever, often in great abundance, and in the spleen, liver, bone 

 marrow, brain, lymph glands and some other organs. It is form- 

 ed abundantly in the black pigment tumors (melanosis) of man 

 and animals, and in extensive melanosis is present in the blood of 

 both man and horse (Schimmeln). So far it has not been found 

 in connection with the extensive destruction of red globules which 

 takes place in anaemia. Schwalbe has developed malansemia ex- 

 perimentally by the hypodermic injection of bisulphide of carbon 

 in rabbits. 



According to one view the melanin is produced in connection 

 with the destruction of red globules in the liver, .spleen, etc., and 

 is thence carried into the blood. This is in keeping with 

 the local formation of the pigment in melanosis. Arnstein how- 

 ever urges that in malarious cases the destruction of the red cells 

 takes place in the blood, and that the haemoglobin, absorbed into 

 the leucocytes, is transformed into melanin, and finally deposited 

 in the tissues by the migrating white corpu.scle. Why the hae- 

 moglobin .set free in anaemia is not similarly transformed, does 

 not appear. The pigmented organ may be quite black in the im- 

 mediate vicinity of the blood vessels, and in its general aspect in 

 chronic ca.ses reddish brown, dark gray, or dark olive. 



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