In the course of a conversation in November 1917, Mr. E. Hutchins, the Chief Veterinary Officer, Uganda Protectorate, drew my attention to an outbreak of rinderpest in the Northern Province of the Protectorate, which first manifested itself in the buffalo of the Chopi Country. The disease was then rapidly spreading through the game in the Glossina morsitans area between Masindi Station and the Kafu River. He pointed out the excellence of the opportunity for investigating the alleged relationship between rinderpest and fly. As I had worked from May till September 1914 in the Northern Province fly belt in association with Mr. W. F. Fiske, I was in a particularly advantageous position to estimate any alteration in the fly distribution which might have occurred as a result of the epidemic. The question had a special local significance, as, should the disease prove fatal to the fly, the introduction of rinderpest among the situtunga on the Islands of Lake Victoria would simultaneously remove the reservoir and the carrier of the mammalian trypanosomes. My release from military duties was duly sanctioned in November 1917, but unfortunate circumstances over which I had no control postponed its fulfilment until April 1918. By this time the disease had almost worked itself out in the fly area, and, what is more to be regretted, the long-deferred rains had commenced throughout the district. The heart of a unique opportunity was thus lost.