In the course of a study of the leucopenia and subsequent hyperleucocytosis that follow the intravenous injection into the rabbit of typhoid bacilli, either living or killed, it was necessary to examine a large number of stained spreads of blood taken before the injection and at various intervals thereafter. It was during these examinations that the present instance of phagocytosis of erythrocytes in the peripheral blood was observed.
In general the leucocytic response in the blood of our rabbits was analogous to that obtained by other workers after similar injections. This reaction consists of two phases; the first a marked leucopenia which appears within a few minutes after the injection and reaches its low point within two hours. The count of white blood cells may drop from normal to as low as 1000 per cmm. and differential counts made at this point show this leucopenia to be in chief part the result of the almost complete disappearance from the blood, as obtained from the ear, of the polymorphonuclear amphophiles.