The committee of the Royal Society came to the conclusion that the thing to be done was to get Colonel Bruce to consent to proceed to Uganda, and to recommend the Foreign Office to obtain from the War Office the temporary detachment of Colonel Bruce for this service. Accordingly Colonel Bruce arrived in Uganda in the middle of March, 1903. Dr. Low and Dr. Christy had already departed, but Dr. Castellani was still at Entebbe engaged in the study of his streptococcus. He mentioned to Colonel Bruce on his arrival that he had on more than one occasion seen a trypanosome in the cerebro-spinal fluid of negroes suffering from sleeping sickness; but, inasmuch as Dutton on the West Coast and Hodges in Uganda had described a trypanosome as an occasional parasite in human blood, he had not considered its occurrence in sleeping-sickness patients as of any more significance than is the occurrence of _Filaria perstans_. Castellani regarded the trypanosome, like the filaria, as a mere accidental concomitant of sleeping sickness, the cause of which he considered to be the bacterial streptococcus which he had so frequently found to be present. Naturally enough, Bruce was impressed by the fact that trypanosomes, of the deadly nature of which he had had ample experience, had been found, even once, in the cerebro-spinal fluid of sleeping-sickness patients; and he immediately set to work to make a thorough search for this parasite in all the cases of sleeping sickness; then under observation at Entebbe. He generously allowed Castellani to take part in the investigation, which resulted in the immediate discovery of the trypanosome in the cerebro-spinal fluid of twenty cases, out of thirty-four examined, of negroes afflicted with the disease; whilst in twelve negroes free from sleeping sickness the trypanosome could not be found in the cerebro-spinal fluid. Castellani returned to Europe three weeks after Bruce’s experiments were commenced, and announced the discovery, which has been, in consequence, erroneously attributed to him, although mainly due to Bruce.