For many years it has been known that intercurrent infections occurring in the course of leukemia are accompanied by a fall in the number of leukocytes. Indeed, it has been hinted in medical textbooks that long remissions may be produced by such complicating diseases. Neutra, 1 in 1903, collected twenty-one cases from the literature, in all of which there was a marked fall in the white cells. Dock, 2 in 1904, in a similar survey of reported cases, found thirty-three cases of leukemia in which intercurrent infections were accompanied by a fall in the leukocytes. Seven of these were miliary and four chronic tuberculosis. The remainder comprised sepsis, typhoid, erysipelas, influenza, empyema and streptococcus, colon bacillus and staphylococcus infection. In only three cases was there a rise in the leukocytes coincident with the infection. In one, the complication was bronchitis, in one, streptococcus infection, and in the third, peritonitis. Apparently