In a memoir recently published, Salvin-Moore and Breinl state that when Trypanosoma gambiense is examined in the blood “it does not seem possible to detect any true dimorphism or trimorphism.” “The three forms often described and alluded to as distinct, consequently appear to be arbitrarily chosen examples in a continuous series of dimensions.” It has always seemed to me very remarkable that the great differences in form and structure, no less than in size, between the slender, ordinary, and stumpy forms of T. gambiense, differences noted by all competent observers, should have been denied by two authors who claim for their methods of technique a superiority over those employed by all other investigators.