A photoelectric method is used to determine the degree of hemolysis produced by specific hemolytic serum on erythrocytes of dogs, taking as a standard the amount required for 50 per cent hemolysis. The requirement of the normal dog red blood cell is 1.2 cu. ml. (±0.7 cu. ml.) of hemolytic serum, under the conditions described in the method.
The red cells of dogs given a sufficient dose of acetylphenylhydrazine to produce a severe anemia, followed by an intense period of blood regeneration, required an amount of hemolytic serum about two to four times greater than in the normal animal (values from 3.0 to 4.8 cu. ml. of hemolytic serum are recorded). This result shows that the reticulocytes and young erythrocytes are much more resistant than the normal adult red cell to the action of hemolytic serum. It was possible by this technic to concentrate the reticulocytes in vitro, destroying selectively the adult erythrocytes of a sample of blood by an appropriate amount of specific hemolytic serum.
The relationship between these results and the high reticulocytosis observed during crisis in hemolytic jaundice is discussed.