536 XI. HEMOGLOBIN CATABOLISM, I 



to other conditions, this need not necessarily be so. It is quite possi- 

 ble that some erythrocytes of increased fragility will be found to have 

 a normal span of life, as well as that erythrocytes of normal fragility 

 have a shorter span of life. Only a few investigations of the life span 

 of erythrocytes in anemias have yet been carried out. Witts and 

 co-workers {3^9,395) have shown that in some anemias, e.g., in 

 idiopathic hypochromic anemia, the linear decay curve of transfused 

 normal cells (c/. Section 3.3.) remains unaltered. In others, e.g., 

 hemolytic anemia, there is an exponential decay, indicating the work- 

 ing of a random process; there is thus evidence for an external lytic 

 factor. In addition to the exponential decay, the linear decay is 

 also more rapid. Since the transfused cells were normal, this is 

 ascribed to a decrease of the protective factor in the plasma (c/. 18^6) . 



6.2. Hemolytic Anemias 



The relative importance of external hemolytic factors and of internal 

 faults of construction of the erythrocyte in the different hemolytic anemias 

 is not yet clear. In sickle cell anemia and in acholuric jaundice, Case found 

 a large proportion of siderocytes, even up to 100% of the red cell count {Jt-15). 

 In these instances there is thus definite evidence for increased intracor- 

 puscular hemoglobin breakdown. The fact that the increased fragility of 

 the cells in acholuric jaundice remains after the clinical picture of anemia 

 has been symptomatically cured by splenectomy is an example of the inter- 

 action of both internal and external factors. 



Spherocytosis has been assumed to be a factor which predisposes to 

 hemolysis {220,1083,1109), although it is not found in paroxysmal hemo- 

 globinuria {375,1881), co\d hemoglobinuria, or march hemoglobinuria {1002). 

 Hemoglobinuria is, however, a rare phenomenon in hemolytic anemia. 



Bergenhem and F&hraeus {220) observed that when plasma was incubated 

 at 37°C. the sedimentation rate of added corpuscles diminished and sphero- 

 cytosis finally ensued. These changes were not observed in flowing blood. 

 They obtained a crude fraction from incubated plasma which showed some 

 of the characteristics of lysolecithin, and suggested that the process might 

 occur in the spleen, where Knisely {155Jf) observed the separation of cells 

 from plasma in the sinusoids. Mellgren {1903) found detectable hemo- 

 globinemia in the reservoir blood of the spleen, which was greatly increased 

 by allowing the splenic blood to stand in vitro {cf. also Ham and Castle, 

 1109). Mason {1881) has assumed that a factor is present in abnormal 

 erythrocytes which causes prolonged stasis in the spleen. It has not been 

 shown, however, that the latter observations are related to the phenomenon 

 investigated by Bergenhem and Fihraeus. Laser {1656) has isolated a lytic 

 substance from blood which shows properties quite different from those 

 reported for their crude substance by Bergenhem and F&hraeus. It is present 

 in an inactive form in normal plasma and may well be of significance in 

 hemolytic anemia. 



There is no doubt of the importance of the spleen, for Mellgren's experi- 



