MEI^AN^MIA. BIvACK PIGMENT IN BLOOD. 



Definition. Melanin, in normal tissues, abnormal. Melanosis Bisulr 

 phide of carbon subcutem. Decomposition of hsemoglobin 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— C44. 2, H3, Ng.g, O^^.g — or black pigment (a close rela- 

 tive of hsematin) 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 malari- 

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

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

 formed 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 

 malanaemia experimentally by the hypodermic injection of bisul- 

 phide 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. Arnsteiu, however, 

 urges that in malarious cases the destruction of the red cells 

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

 the leucocytes, is transformed into melanin, and finally deposited 

 in the tissues by the migrating white corpuscle. Why the haemo- 

 globin set free in anaemia is not similarly transformed, does not 

 appear. The pigmented organ may be quite black in the imme- 

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

 chronic cases reddish brown, dark gray, or dark olive. 



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