DISINTEGRATION OF THE DYING CELL 533 



In vivo such a rapid hemolysis is a rather rare phenomenon. If the concen- 

 tration of hemoglobin dissolved in the plasma reaches 100-140 mg. per 100 

 ml. corresponding roughly to 0.4% of the total circulating hemoglobin, 

 hemoglobin is excreted in the urine {3153). Hemoglobinemia has been 

 observed after intoxication with arsine, in blackwater fever, in paroxysmal 

 hemoglobinuria, in a few other hemoglobinurias, and in some cases of hemo- 

 lytic anemia. It has not been observed, however, in a great number of 

 hemolytic anemias or after administration of phenylhydrazine, in spite of 

 the rapid breakdown of corpuscles under these conditions. Fairley {735) 

 distinguishes three groups which indicate the degree qf rapidity of hemolysis: 

 (a) hemoglobinuria, methemalbuminemia, and hyperbilirubinemia; {h) 

 methemalbuminemia and hyperbilirubinemia; and (c) hyperbilirubinemia 

 alone. In the last case all the damaged corpuscles are phagocytized before 

 hemolysis occurs. 



It is not known if the cells in the reticuloendothelial system {cf. Section 7.) 

 ever phagocytose erythrocytes which have not been damaged, either by 

 their normal catabolic processes or by the action of external agents. If intra- 

 vascular hemolysis occurs, it appears certain that the greater part of the 

 pigment is destroyed by these cells, provided that the hemoglobin level does 

 not exceed the renal threshold, when the pigment is excreted. 



Corpuscles may undergo mechanical destruction by being thrashed to 

 bits in the circulation (for a review of the literature cf. Mellgren, 1903). 

 Many physiologists have assumed that this is the normal method of destruc- 

 tion. Hemoglobinemia has, indeed, been observed in a large proportion of 

 young athletes after long cross-country runs {1001). It is not known, how- 

 ever, whether the cells which are destroyed are a random fraction of the cell 

 population or whether they consist of aged cells. Hemolysis by fragmentation 

 would only be compatible with the shape of the normal decay curve if the 

 cells destroyed were, in fact, of the latter type. 



Soaps are hemolytic agents. It has been known for some time that inges- 

 tion of high fat diets causes an increase of the excretion of urobilinogen 

 {1009,im,lJfUM20). In a number of papers {9J^8M9,im,177Jt,1778, 

 1779) Johnson and co-workers have brought forth evidence for the hemo- 

 lytic action of fat in vivo. In dogs with bile fistulae bilirubin excretion was 

 found to be increased by high fat diet and also after intravenous injection of 

 fatty acids or soaps (8 mg. per kg. injected over a period of one hour). 

 Samples collected from the lacteals and thoracic ducts of dogs after fat 

 absorption were found to have marked hemolytic properties. Hemolysis 

 was not observed when the red cells were mixed with lipemic serum although 

 the cell fragility increased. Davis {5J^1) also observed a diminution of red 

 cells and hemoglobin in dogs fed lard and 10 mg. of choline per day. No 

 studies of the life span of the erythrocytes on these high fat diets are yet 

 available and would appear to be necessary before the significance of fat 

 hemolysis can be properly assessed. 



Considerable importance has been attributed to hemolysins arising from 

 the Bergenhem-F&hraeus effect {220; cf. also 729,1903 and Section 7.4.) in 

 normal erythrocyte destruction, while Laser {1656) has shown the presence, 

 in an inactive form, of a strongly lytic substance in normal plasma. It seems 



