into British East Africa,* nor, so far as has been reported, down the Nile. No curative treatment for the disease has yet been discovered; nor is there any authenticated instance of recovery.

The appalling mortality produced by this disease in Central Africa naturally caused the greatest anxiety to his Majesty's Government, which had but just completed the railway from the East Coast to the shores of lake Victoria Nyanza, and had established a prosperous and happy rule in that densely populated region. The official medical men on the spot, though capable and experienced practitioners, were unable to cope with this new and virulent outbreak. The Foreign Office, having no imperial board of hygiene and medical administration to apply to in this country, sought the assistance of the Royal Society of London.

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 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 three 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 10,000l. 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

* The disease has actually entered into the administrative area known as British East Africa, but has not made any rapid progress towards the coast. According to a recent report by Dr Wiggins, the disease is confined in British East Africa, as in Uganda, to those areas in which Glossina palpalis occurs.

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 microorganisms 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-eels,' and one of a great class of parasites) which he had discovered in the blood of negroes and had named Filaria perstans.

The occurrence of minute worms (true worms, not unicellular plants or protozoa) in the blood of man was first made known by Dr Timothy Lewis, who described the Filaria sanguinis hominis, as well as some other most important blood-parasites, some years ago (1878), when officially engaged in an enquiry into the cause of cholera in Calcutta. Subsequently, in China, Manson found that these little blood-worms were sucked up by mosquitoes when gorging themselves on the blood of a patient. It is, indeed, difficult to imagine how they should escape passing into the mosquito with the blood. Manson suggested that the minute worms (known to be the embryos of a worm which, when adult, is about one fifteenth of an inch long) are obliged to pass through a mosquito in order to accomplish their development; but no proof of this suggestion has ever been made. We know by abundant and repeated demonstration and experiment that another blood-parasite-the malaria parasite-must pass through a mosquito, in whose body it developes, and by which it is carried to a new victim of infection. This was suspected long ago by both peasants and doctors, and

experimentally proved by Ross; but no such proof has been given of the relation of Lewis' blood-worm to a mosquito. The so-called Filaria perstans, discovered by Manson in the blood of negroes, appears to be very different from the Filaria sanguinis hominis of Lewis. It is not known how it gets into the blood; and it is very astonishing, and much to be regretted, that none of the medical men who have had it under observation have given a proper anatomical account of it. It appears that this worm is very common in the blood of negroes in tropical Africa; and, as it was found in several cases in the blood of individuals attacked by sleeping sickness, Sir Patrick Manson was justified in entertaining the view that this parasite was the cause of the disease.

One of the first results obtained by the commission sent by the Royal Society committee to Uganda was the proof-which had, indeed, been already furnished by the resident medical officers of the Uganda Protectorate-that Filaria perstans, though remarkably abundant in the blood of the negroes of Uganda, can have nothing to do with sleeping sickness, since, though it often occurs in persons attacked with that disease, it also exists in districts where sleeping sickness is unknown; and, further, many cases of sleeping sickness have been observed in which no Filaria perstans has been discovered in the blood or other parts of the body.

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 despatch 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 enquirywould 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 twelve 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.

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.

Bruce continued his work in Uganda until the end of August 1903, having been joined there by Colonel Greig of the Indian Army, who has continued the work of the Royal Society's commission since Bruce left. Other valuable observations have been carried out by various medical men officially connected with the Uganda Protectorate. Bruce soon showed that in every case of sleeping sickness, when examined with sufficient care, the trypanosome parasite is found to be present in the cerebro-spinal fluid. He also showed that it is absent from that fluid in all negroes examined who were not