55 Deutsche Klinik, 1850.
56 Virchow's Archiv, Bd. i.
There is still some difference of opinion as to the mode of origin of the pigment. Most writers hold that it results from the destruction of the red corpuscles in the spleen and liver, and from these situations the pigment gets into the blood; but more recently Arnstein57 and Kelsch58 have urged the view that the melanæmia is the primary process, the destruction of corpuscles going on in the blood itself, and the particles and coloring material taken up by the leucocytes are transformed into melanin, and then the cells collect in the spleen, liver, and bone-marrow, producing the condition of melanosis. It is probable that the older view is the true one, and we may regard the process as an exaggeration or intensification, under the stimulus of the malarial poison, of the normal process of blood-destruction which goes on in the spleen and bone-marrow, and under some circumstances in the liver and lymph-glands. We can often trace in the cells of these organs the stages of transformation from red corpuscles to melanin-granules, just as can be done in the tissues in the neighborhood of an extravasation, where also the process is chiefly intracellular (Langhans). On the other hand, in those very states in which the red corpuscles are destroyed in the blood and the hæmoglobin set free, we do not find melanæmia. It happens occasionally in fevers that we meet with colorless cells in the blood containing red blood-corpuscles, which in time would be transformed into pigment, but, so far as we know, such a condition has not been observed in the blood in malaria. The connection between the fever paroxysm and the appearance of the pigment in the blood depends, most likely, on changes in the volume of the organs under the influence of the fever, whereby cells containing the pigment are dislodged and get into the circulation. This explains, too, their rapid appearance in some cases with the onset of a paroxysm. No doubt, as Virchow originally taught and as well shown in Gussenbauer's59 observations, the pigment may result from the diffusion of the coloring matter and gradual precipitation of it in the granular form within the protoplasm of colorless cells; but of the occurrence of such a process in the circulating blood in malaria we have no satisfactory evidence, and we incline to the belief that the melanosis of the organs is the primary condition, while the melanæmia is secondary and inconstant.
57 Loc. cit., and ibid., lxxi.
58 Archiv de Physiologie, 1875.
59 Virchow's Archiv, lxiii.
Occasionally, in cases of extensive melano-sarcoma, pigment-granules may be found in the blood in large numbers, and even appear in the urine and be deposited in the organs and skin. In a few instances also free pigment has been observed in the blood in Addison's disease.
PROGRESSIVE PERNICIOUS ANÆMIA.
DEFINITION.—Extreme and progressive anæmia developing without evident or apparently adequate cause.