The theory that the larger wild mammals, commonly called “big game,” are solely and entirely responsible for the presence of tsetse-flies, has become so firmly fixed in the mind of the average “man in the street” in South Africa, that no amount of contrary argument or even proof, were such forthcoming, could ever have much effect in altering his opinion. The newcomer quickly assimilates the same idea, and after a time begins to voice it as assertively as his mentor. It is thus most difficult to obtain really reliable data. An investigator, beginning an enquiry with an open mind, finds himself flooded with such a mass of apparently well substantiated statements, provided by experienced and obviously sincere persons, that he can with difficulty keep his mind free from a certain amount of bias. Starting from the assumption that the presence of fly depends upon that of game, arguments against the continued existence of the latter quickly multiply in the public mind. I was talking to a friend the other day, and he mentioned that he had been replying to some questions upon this very subject. He was no partisan of the anti-game movement, but regretfully expressed his conviction that in order to get rid of tsetse-fly it would be necessary to abolish the larger animals. I ventured, to ask for some clear instance of this interdependence. He was unable to quote any first-hand evidence which might not have been explained away, and his main contention, in short, was, “Of course the fly is dependent upon the game, everyone with any experience knows that; ask any old hunter or native.” This, I think, about sums up the ideas of the majority of people, and, if further argument is deemed necessary, the assumed general disappearance of the fly after rinderpest is pointed to as affording conclusive proof. The presumption is, of course, that the fly, deprived of its means of subsistence, died of starvation. An acquaintance with some of the districts visited by the epidemic would however by no means indicate that this was the real cause of the phenomenon, where it occurred. A study of the effect of rinderpest upon the relations between fly and game, might indeed, were it possible always to obtain accurate data, shed some new and interesting light upon the whole subject.