The publications of Arneth in 1904 came as the result of the impetus given to the study of hematology by the introduction of Ehrlich's blood stains. Up to his time morphologic studies had been more or less limited to hematologic conditions. While studying the nuclear structure of the neutrophils in infection, Arneth1 found that there seemed to be a constant relationship between the severity of the infection and the number of nonsegmented neutrophils. If the infection was very severe, neutrophils with three, four or five-lobed nuclei would disappear, to be replaced by others with nonsegmented nuclei. With the abatement of the infection, the nonsegmented neutrophils would rapidly be replaced by the mature forms. His later observations on the other leukocytes, though painstaking and correct, never received confirmation. Even his neutrophilic subclasses, though widely employed over an extended period of time, were never universally adopted. Schilling,2 finding this classification