CLINICAL and laboratory studies have led me to believe that pemphigus vulgaris is a generalized infection.1Evidence to support this belief was sought by an examination of the blood picture and is presented in this paper. Generalized infections produce qualitative and quantitative alterations in the blood picture, which include (a) leukocytosis, which is generally due to an increase in the number of cells of the polymorphonuclear series; (b) changes in the polymorphonuclear leukocytes (these include an increase in the proportion of immature and a corresponding decrease in that of the mature cells; the severer the degree of infection or toxemia resulting from infection, the higher is the proportion of immature cells; in this paper the term "immature" is used to designate the polymorphonuclear leukocytes in which the nucleus is indented but not segmented and also Schilling's staff forms with unsegmented nuclei, which may be in the shape of a