THE SLEEPING SICKNESS 167 



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 trypano- 

 some could not be found in the cerebro-spinal fluid. 

 Castellani returned to Europe three weeks after Bruce's 

 experiments were commenced, and announced the dis- 

 covery, 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 Pro- 

 tectorate. 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 

 afflicted with the disease, but made the very important 

 discovery that the trypanosome is present in the blood 

 (not the cerebro-spinal fluid) of twenty-eight per cent, 

 of the population in those areas where sleeping sickness 

 occurs, the persons thus affected having none of the 

 symptoms of sleeping sickness, but being either perfectly 

 healthy or merely troubled with a little occasional fever. 

 The subsequent history of all the cases thus observed 

 has not as yet been recorded. But in many such, even 

 in some Europeans, the earlier presence of the trypano- 

 some in the blood has been followed by its entry into 

 the cerebro-spinal lymphatics, and by the fatal develop- 

 ment of sleeping sickness. 



