While Drs. Low and Christy occupied themselves with settling this question as to the connexion of _Filaria perstans_ with the disease and carried out a careful study of its clinical aspects, Dr. Castellani examined the brain and spinal cord of those who died from sleeping sickness, for bacteria. He found again and again an extremely minute globular vegetable parasite--of the kind known as streptococcus--which he concluded to be the cause of the disease, although he had not produced the disease experimentally by inoculating an animal with this microbe. In the early part of 1903 these were the only results obtained by some six months’ work of the medical men sent out by the Royal Society’s committee; and it was felt that something more must be done. The investigation of a disease hitherto little known and studied is one of the most difficult tasks in the world, requiring the highest scientific qualities. Any serious attempt to deal with the sleeping sickness in Uganda would, it was at length recognised, require the dispatch of a man of proved capacity and experience, provided with full powers and with trained men as his assistants. No such men are provided by the public service of the British Empire. To detach a medical man of recognised insight and experimental skill from his practice--even were it possible to find one specially qualified for the present enquiry--would involve the payment of a large fee, which neither the Royal Society nor the Foreign Office could command. What, then, was to be done? Fortunately there was one man in the public service, recently appointed to be one of the chiefs of the educational arrangements of the Army Medical Department, who had shown himself to be especially gifted in the investigation of obscure diseases. This was Colonel David Bruce, F.R.S., who, some fifteen years ago, established the existence of Malta fever, as an independent disease, by his clinical observations and by the isolation and cultivation of the parasitic bacterium causing it; and who, further, when employed by the governor of Zululand a few years later (1895) to investigate the celebrated tsetze-fly disease of South Africa, had discovered, contrary to the assertions and prejudices of a large number of African sportsmen and explorers, that the horse and cattle disease known as nagana or tsetze-fly disease was due to the presence in the blood of the affected animals of a peculiar cork-screw-like animal parasite, the _Trypanosoma Brucei_. This is carried by the bite of the tsetze-fly from the blood of wild game, such as buffalo and antelope, where it does no harm, to the blood of domesticated animals, in which it multiplies and proves to be the source of a deadly poison causing death in a few weeks. The experiments by which Colonel Bruce demonstrated this relationship of tsetze-fly, trypanosome parasite, wild big game, and domesticated animals, were universally regarded as masterly both in conception and execution, and absolutely conclusive.