38 



Scientific Proceedings (125) 



The method of washing and shaking the cells has already been 

 described. Healthy adult animals with bloods showing the same 

 general ratio of hemoglobin to corpuscle bulk were employed. 

 The amount of hemoglobin set free was read off as acid hematin 

 by comparison with a standard series of tubes containing graded 

 solutions of the substance. In one experiment washed specimens 

 from 20 rabbits, shaken at the same time, yielded from 1.2 per 

 cent, to 5.4 per cent, of their hemoglobin; in another set of 27 

 individuals, 0.8 per cent, to 5.7 per cent, was set free. The range 

 of resistance here exhibited was in striking contrast to the uni- 

 formity of the response to a specific hemolysin in graded dilution. 

 The resistance to hypotonic salt solution, while much less uni- 

 form than this latter, was still not so frequently variable as that 

 to shaking, though occasional instances of marked individual 

 susceptibility were encountered. Generally speaking, resistance 

 to the one means of cell injury yielded no indication of that 

 to the other. 



The individual blood differences disclosed by the shaking 

 method persisted throughout the period of our observations (43 

 days). They were independent of sex, weight, normal varia- 

 tions in bone-marrow activity as indicated by the percentage of 

 circulating reticulocytes, and of moderate intercurrent changes 

 in the hemoglobin percentage and in the number of red cells per 

 cu. mm. of blood. They did not tally with the individual varia- 

 tions in the rate of breaking down of artificial subcutaneous 

 extravasates. The spleens of the individuals with fragile cells 

 proved to be no larger, and erythro-phagocytosis was no more 

 marked than in the animals with resistant cells. The organs of 

 all were normal. 



It would be difficult to employ the resistance of the blood to 

 shaking as a clinical test. Pathological variations in the pigment- 

 stroma ratio, and in corpuscle size are among the more serious 

 complicating obstacles. 



