A committee of that society had already undertaken the study of malaria at the request of the Secretary of State for the Colonies, and had sent out young medical men as a commission to make certain enquiries and experiments on that subject and report to the committee in London. The sleeping sickness enquiry was undertaken by the same committee; but unfortunately very insufficient funds were placed at its disposal. When the South African cattle-owners found their herds threatened six years ago by a new form of mortal disease--‘the East Coast fever’--the South African Government accepted the offer of Dr. Robert Koch, of Berlin, to undertake the investigation of the disease and the discovery, if possible, of a remedy, for the sum of £10,000. No such sum was at the disposal of the committee of the Royal Society. They were obliged to send out young and enterprising medical men, practically without pay or reward, to see what they could do in the way of determining the cause of, and, if possible, the remedy for, the terrible sleeping sickness raging in Uganda and destroying daily hundreds of British subjects. The committee set to work in the summer of 1902, and sent out Drs. Low, Christy, and Castellani to Entebbe, the capital of Uganda. The guesses as to the cause and nature of sleeping sickness at the time when this commission set forth were very various. Some highly capable medical authorities held that it was due to poisonous food. The root of the manioc, on which the natives feed, was supposed to become infected by some poison-producing ferment. A more generally received opinion was that it was caused by a specific bacterium which invades the tissues of the brain and spinal cord. Several totally different micro-organisms of this sort had been described with equal confidence by French and Portuguese investigators as the cause of the sleeping sickness studied by them in West Africa or on the Congo. Sir Patrick Manson, the head of the British Colonial medical service, an authority of great experience in tropical disease, had put forward the suggestion that the sleeping sickness was due to the infection of the patient by a minute thread worm (allied to the ‘vinegar-eel,’ and one of a great class of parasites) which he had discovered in the blood of negroes and had named _Filaria perstans_.