248 Prof. Minchin, Lieut. Gray, and late Lieut. Tulloch. [July 10, 



first sight that any trypanosomes found in the bodies of these tsetse-flies 

 caught in a Sleeping Sickness area would be developmental stages of 

 T. gamhiense. We felt no doubt at the outset of our investigations that these 

 fresh fly trypanosomes were to be identified with T. gamhiense. Koch* 

 evidently worked on the same assumption, since in his comparison of the 

 supposed developmental stages of T. brucii and T. gamhiense there can be 

 no doubt that he has taken the form which has been called T. grayi for a 

 developmental phase of T. gamhiense. As we proceeded, however, with our 

 investigations we were gradually led to doubt any connection between 

 these " fresh fly trypanosomes " and Sleeping Sickness. In order to 

 determine this point we carried out a number of experiments on flies caught 

 on the island of Kimmi. This island was chosen because it swarmed with 

 these tsetse-flies, of which a high percentage contained trypanosomes, and 

 because it was, and has been for a very long while, quite uninhabited. 



Kimmi is a small island of the Sesse group, about two miles long by a 

 mile wide (see map). There is a narrow strip of sandy shore all round it, the 

 remainder of the island being covered with thick undergrowth and forest. On 

 the foreshore are many ambatch trees, where cormorants, other diving birds, 

 and weaver birds are very plentiful. This island is a regular feeding ground 

 for hippopotami and is crossed in all directions by their tracks. Crocodiles are 

 also very numerous. Kimmi is situated about 15 miles from Entebbe and 

 is two miles from Nsadzi Island in the one direction and from Kome Island 

 in the other. For more than a year this island has been quite uninhabited 

 and natives now never visit it. The whole island swarms with tsetse-fly 

 {G. palpalis). In spite of the total absence of human beings on Kimmi 

 Island, we found that more than 7 per cent, of the tsetse-flies caught there 

 contained trypanosomes of one or other of the two types mentioned, while 

 only 1'7 per cent, of the flies caught on the main land near Entebbe, a place 

 with a numerous population, among whom Sleeping Sickness is common, 

 contained similar parasites. 



Our method of experimenting with these flies was as follows : — Our camp 

 with our apparatus and experimental animals was placed on the neigh- 

 bouring healthy island of Nsadzi, in a region free from fly and where there 

 is no Sleeping Sickness. A steam-launch was placed at our disposal by the 

 authorities and by means of it batches of flies were brought back from 

 Kimmi, so that we were not obliged to take possibly infected native canoe- 

 men, a class among whom Sleeping Sickness is very common, to this island. 

 These Kimmi flies were divided into batches and each batch assigned to 

 a particular animal (monkey, rat, guinea-pig, or hen) on which the batch 

 * ' S.-B. k. pr. Akad. Wiss. Berlin, 1905, pp. 958—962. 



