HISTORICAL REVIEW
Brouardel is generally referred to as the first investigator who made studies of the blood in smallpox. In 1874 he published his observations on the behavior of the leukocytes in this disease and emphasized the presence of a leukocytosis "during the febrile remission between the period of eruption and of suppuration. He found them diminished during suppuration, an increase at this time or during desiccation signifying to him secondary pyogenic infection."1Corroboration of these findings and additional observations, particularly the studies of the morphologic changes of the leukocytes and the differential count, were made by a number of men; notably, Pick (1894), Rogers (1900), Courmont and Montagard (1900), Weil (1901), Ferguson (1902), Perkins and Pay (1903), Magrath, Brinkerhoff and Bancroft (1904), and others. Kammerer (1910) and Erlenmeyer (1913) and, more recently, Pantasis (1924) reviewed the literature extensively and reported the analysis of their own findings. Schilling, during an