296 DISTURBAXCES OF CIRCULATION 



b}^ the proteases of the leueoeytes, tissue-cells and blood plasma ; the 

 g'lobin is thus digested away and the soluble products carried off, 

 while the insoluble liematin remains.-^ The hematin gradually un- 

 dergoes further changes, forming an iron-free i)igment (hcinatoulin) 

 and an iron-containing pigment (hemosiderin) . 



Hematoidin is nearly or quite identical with the bile-pigment, hili- 

 rubin, and is absorbed from the hemorrhagic extravasation and elimi- 

 nated as bilirubin in the bile. Possibly some of the hematoidin un- 

 dergoes transformation into nrobiUn, and is then eliminated in the 

 urine. Hemosiderin seems to be relatively insoluble and, therefore, 

 is more slowly removed, so that it may be found at the site of a hem- 

 orrhage after the other evidences of blood extravasation have been 

 removed. It may be easily demonstrated by staining with potassium 

 ferrocyanide, the Prussian blue that is formed being readily dis- 

 tinguished. Unstained hemosiderin generally appears in the form 

 of brown or yellowish-brown granules, never as crystals. After a 

 time the hemosiderin is taken away, and probably is to a greater or 

 less extent deposited in the liver and spleen, either as hemosiderin 

 or as some other iron compound. Eventually it is probably utilized 

 to make new hemoglobin ; at any rate, the iron liberated by the breaking- 

 up of hematin within the body does not appear to be eliminated. "- 



The changes in the red corpuscles described above are not at all 

 peculiar to extravasated blood, but are quite the same as the changes 

 that are going on continuously and normally in the blood. Red cor- 

 puscles are short-lived, being but non-nucleated fragments of cells, 

 and they are continually disintegrating with the production of iron- 

 free pigments that are excreted as the coloring-matters of the bile and 

 urine, while the iron is worked over again into new hemoglobin 

 after a varying period of storage in the tissues, particularly in the 

 spleen and liver. The destruction of red corpuscles under normal 

 conditions seems to take place chiefly in the spleen, bone-marrow, 

 and hemolymph glands, where injured or decrepit c()ri)uscles are 

 taken out of the blood by the phagocytic endothelial cells, and de- 

 composed by intracellular enzymes. In hemorrhagic extravasations 

 the changes are essentially the same; some corpuscles are destroyed 

 by phagocytes, but more by extracellular enzymes. The products 

 of decomposition also seem to be no different from those formed dur- 

 ing normal katabolism of hemoglobin, and they meet the same fate in 

 the end. 



If the hemorrhages are very abundant, some hemoglobin may be 

 absorbed as such and appear in the urine, but this ])rol)nbly seldom 

 happens unless red corpus('le^'. are also being destroyed in tlie circu- 

 lating blood.--'' An increased amount of iron accumulates in the 



21 More fullv disciisscHl in tlie consideration of "Pitrnu'ntaiion." Clia|). xvi. 



22 See Morishima, Arch. f. cxp. Tath., 1898 (41), 2!)]. 



22a In cerebral lieniorrliase the blood serum niav be frreenisli and somewhat 



