576 XII. HEMOGLOBIN CATABOLISM, II 



the absorption band of the biHpurpurin zinc compound which was 

 found at 638 mfx, not at 623 m/x, the position of the band of the zinc 

 compound of mesobiHpurpurin. From these experiments it must be 

 concluded that very Httle or no conversion of mesohematin to bile 

 pigment has taken place. Unaltered mesohematin was found in the 

 bile and in the organs of the animals. 



The latter is in agreement with the observations of other workers. 

 Anderson and co-workers (5^,55) found that hematin injected into 

 dogs and monkeys was taken up by reticuloendothelial cells, but not 

 metabolized. Brown {352,353) showed that hematin remains for 

 weeks with but slight and slowly progressing alterations. Rigdon 

 (2254-) observed a slow breakdown of malarial hematin to an iron 

 pigment in the tissue's.* We have mentioned abov^e the long per- 

 sistence of methemalbumineinia after a single hemoglobin injection. 

 It is possible that hematin is finally converted into bile pigment but 

 this reaction is far slower than that of hemoglobin. 



Nothing definite is known yet about the mechanism of the forma- 

 tion of hematin and methemalbumin from hemoglobin. Duesberg 

 assumes that the damaged liver converts hemoglobin to hematin, 

 while Fairley and Watson ascribe to the liver only the function of 

 absorbing methemalbumin and converting it to bile pigment. Fairley 

 believes in a conversion of hemoglobin to methemalbumin in the cir- 

 culating blood as an additional pathway to its normal conversion to 

 bile pigment in the reticuloendothelial cells. This is supported by 

 the occurrence of methemalbumin in hemolytic conditions in which 

 there is little evidence of liver damage, and in hemoglobinemia. 

 Methemalbuminemia is found in rapid hemolysis, but is not neces- 

 sarily accompanied by hemoglobinemia. 



In hemolytic anemia splenectomy causes a simultaneous decrease 

 of methemalbumin and bilirubin in the blood. Fairley found forma- 

 tion of methemalbumin from hemoglobin and hemtglobin on incuba- 

 tion with plasma at 37° (734.)- These experiments cannot be consid- 

 ered, however, as a satisfactory model of methemalbumin formation, 

 since the conversion occurred only at an unphysiologically high pH, 

 caused by the loss of carbon dioxide from the plasma in vitro. Met- 

 hemalbumin in the plasma is found without hemoglobin being observed 

 in the corpuscles (c/. 2254)- 



Sight should not be lost of the fact that the amount of hematin 

 or methemalbumin found is usually very small if compared with the 



* Plumier {2158aa) found no increase of plasma iron after injection of hematin. 



