A fatal disease so rare that in the third of a century following the original description only 4 cases of it were reported should merit only a passing or academic interest. However, when 5 other cases of the disease, which is a definite clinical entity, appear in southern Michigan in the course of a few months a new diagnostic problem is unquestionably thrust on physicians. Darling,1in 1906, was the first to note in smears and sections taken at autopsy from the viscera of a Negro who had died at the Ancon Hospital in the Canal Zone a peculiar coccus-like organism which packed the endothelial cells. In the ten months after the first case he observed the same histologic picture in the cases of 2 other residents of Panama.2Clinically, the syndrome (splenomegaly, irregular pyrexia and leukopenia) resembled that of kala-azar, and the microscopic appearance was so similar