512 Colonel David Bruce [April 22, 



attention to what is revealed on a careful microscopical examination 

 of the blood of these cases. If the blood from a case of sleej^iug 

 sickness is examined under a high-power microscope, an active, 

 wriggling parasite may be seen, which is known by the name of try- 

 panosome. 



Here (Fig. 3) is a representation of the trypanosome found in 

 sleeping sickness. 



These blood parasites belong to the lowest group in the animal 

 kingdom, viz. the protozoa. The trypanosome consists of a single 

 cell, and in its best known form is a sinuous, worm-like creature, 

 provided with a macronucleus and a micronucleus, a long terminal 

 flagellum, and a narrow fin-like membrane, continuous with the 

 flagellum and running the whole length of the body. When alive 

 it is extremely rapid in its motions, constantly dashing about, and 

 lashing the red blood corpuscles into motion with its flagellum. It 

 swims equally well with either extremity in front. 



Among the first to draw attention to these blood parasites was 

 the late Surgeon-Major Timothy Lewis, F.R.S. R.A.M.C. ; he dis- 

 covered a trypanosome, in 1888, in the blood of rats in India, to 

 which was afterwards given the name of Trypanosoma Lewisi. This 

 rat trypanosome is found all over the world, and even in Uganda 

 the blood of the ordinary common wild field rat was often found 

 to contain myriads of these creatures. This trypanosome does not 

 appear to do any great harm, or to have any effect on the health of 

 the rats. The next important trypanosome was found also in 

 India, in the blood of horses suffering from surra. This disease, 

 surra, is closely related to the tsetse-fly disease of South Africa, or, 

 as it is called by the natives, nagana. 



The trypanosome which causes tsetse-fly disease lives in the 

 blood of the wild animals, such as the buffalo and various antelopes, 

 without evidently interfering with their health, but when trans- 

 ferred by the tsetse fly from the blood of these animals to that 

 of the domestic animals, it causes the death of the latter. Almost 

 all the domestic animals are highly susceptible to nagana, especially 

 horses, dogs and cattle, and even monkeys, but curiously enough 

 man himself is insusceptible. 



But now let us return to our examination of the blood of cases of 

 sleeping sickness (Fig. 4). The method of examination is simple: 10 c.c. 

 of blood are drawn, by means of a hollow needle, from one of 

 the veins of the arm, and this is then centrifuged to get rid, as far 

 as possible, of the red blood corpuscles. When this has been done 

 the clear fluid is decanted off and again centrifuged, and the 

 sediment now resulting is subjected to microscopical examination. 



I draw your attention to this table giving the result of the 

 examination of sixteen cases, and here you find that in every case, 

 with the exception of one, this trypanosome is found. In all 

 probability it would have been found in this case if there 

 had been an opportunity for further examination, but the man 



