[Erythrocyte volume in man and various animals after the addition of glucose]

The optimal transmission of very diluted blood samples from 11 vertebrate species and man were measured. The red cells of 10 species reduced their volume when glucose or equi-osmotic amounts of sodium chloride were added. Only the erythrocytes of man and monkey (Japanese macaques) did not reduce their volume after addition of glucose or renormalized or overcompensated minor transitory changes. This increase of the volume of human red cells is, however, too low for noticeable viscosity changes of whole blood to be caused, if any. The different response of red cells to glucose makes a simple differentiation between animal and human blood samples possible, provided that primates other than man are excluded.