762 APPENDIX TO THE DISEASES OF THE SPLEEN. 



cells in the spleens of animals, which some observers regard as phys- 

 iological, others as pathological, as well as the fact that in melanaemia 

 the pigment is almost always most abundant in the spleen, certainly 

 favors the idea that the pigment is chiefly formed in the spleen, but 

 does not prove that it is formed there only, and is not formed in other 

 organs at the same time. Frerichs describes a case where he found 

 no pigment in the spleen, while he found so much in the liver, that he 

 was obliged to regard this organ as the place where it was formed. 



The extensive occurrence of pigment in the blood presupposes 

 extensive destruction of red blood-corpuscles. Whether this takes 

 place exclusively in the spleen or whether it takes place in other 

 organs at the same time, all observations prove that it is due to the 

 influence of malarial infection. The milder forms of simple intermit- 

 tent fever do not, however, appear to cause the formation of pigment 

 hi the blood at all or else only moderately, and only the severe and 

 obstinate forms, but particularly the pernicious intermittent, appear to 

 cause the higher grades of melancemia in this country. The corre- 

 sponding reports of physicians in the tropics, about the dark color of 

 the different organs, particularly of the brain, in the bodies of patients 

 that have had remittent fever, render it very probable that this form 

 of malarial disease also constantly, or at least very frequently, causes 

 melanaemia. 



It is very probable that the dilatation of the blood-vessels and the 

 consequent retardation of the current of blood (see page 711) become 

 BO great in pernicious intermittent, and in remittent marsh-fevers of 

 the tropics, that the blood stagnates in the spleen. We might further 

 suppose that the corpuscles in the stagnating blood are destroyed, and 

 hence an altered pigment is developed from their hematin, processes 

 which we often observe in stagnating extravasated blood. This ex- 

 planation of the formation of pigment in a purely mechanical way is 

 refuted by the fact that in intermittent fever the enlargement of the , 

 spleen, and consequently the retardation of the current of blood 

 through it, may be very decided without the occurrence of melanaemia ; 

 and, on the contrary, melanaemia is found in cases where the spleen is 

 only moderately enlarged. Hence we must suppose that marsh miasm 

 has a pernicious influence on the red corpuscles in some other way 

 that we do not yet know ; and that in our country only in certain 

 epidemics, but in the tropics in the endemic fevers, this influence fre- 

 quently or constantly causes an extensive necrosis of the red blood 

 corpuscles, and the formation of pigment from its hematin (Grie 

 sing&r). 



Virchow's labors on the* subject of pathological pigments readily 

 explain why the pigment found in the blood appears not only as free 



