Lasting individual differences in the resistance of normal bloods to shaking

In previous papers observations have been recorded which indicate that the normal destruction of red cells is accomplished, in part at least, by a fragmentation of the elements while circulating 1 . It has seemed possible that the behavior of cells shaken in vitro may yield some indication of their resistance to the fragmenting process.

Marked differences in the red cells from different species have already been disclosed by the shaking method 2 . Further observations have now been made. Shaking which suffices to liberate 10-25 per cent. of the hemoglobin contained in a suspension of washed cells of the rat brings out only 4 per cent. of the pigment from an average specimen of rabbit cells, 1 per cent. from monkey blood, and a mere trace from human blood. Dog corpuscles are among the most labile, as many investigators can attest who have striven to obtain plasma untinted by hemolysis.

The variation in the resistance of individual bloods of a single species, the rabbit for example, are by no means inconsiderable.

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 percent. to 5.4 per cent. of their hemoglobin; in another set of 27 idividuals, 0.8 per cent. to 5.7 per cent. was set free. The range of resistance here exhibited was in striking contrast to the uniformity of the response to a specific hemolysin in graded dilution.