130 INSECTS AND MAN 



examination of a stained trypanosome, under a high power 

 of the microscope, shows that it is a single-celled organism, 

 pointed at either end, and possessed of a membrane ex- 

 tending the whole length of the cell. This membrane 

 terminates at its anterior end in a flagellum, arising from 

 a minute structure known as a blepharoplast. During life 

 the organism is exceedingly active, wriggling about in the 

 liquid portion of the blood, the plasma, by means of its 

 flagellum, which lashes like a whip and is controlled by 

 the blepharoplast, the while the membrane undulates, after 

 the manner of the dorsal fin of certain fishes. Some try- 

 panosomes are harmless, or, at any rate, are not the cause 

 of disease; they simply live as parasites in the blood of 

 certain hosts ; others are the cause of tsetse-fly disease, or 

 nagana, surra, dourine, and mal de caderas in cattle, and 

 to all these diseases, whether in man or animal, the general 

 term trypanosomiasis is applied. Sleeping sickness, with 

 all its distressing symptoms of lassitude, paralysis, and 

 eventual coma, is, in reality, the final stage of human 

 trypanosomiasis. 



As the African Continent was opened up for trade, sleep- 

 ing sickness spread over the tropical area from west to 

 east, like an all-embracing octopus. In 1908, the first cases 

 were reported from Nyasaland, and, in the following year, 

 Rhodesia came under the fatal spell; its appearance in 

 the latter colony caused considerable astonishment to the 

 medical profession, for the vector, Glossina palpalis, had 

 never been found in that part of Africa. The blood of an 

 European patient was examined, and was found to contain, 

 not Trypanosoma gambiense, which up to that time had 

 been looked upon as the sole cause of the disease, but a 

 new organism which was named Trypanosoma rhodesiense, 

 after the colony where it first came to light. The discovery 

 was startling in the extreme, and of such importance that 

 Drs Kinghorne and Yorke were at once dispatched to 

 North-East Rhodesia, by the Liverpool School of Tropical 



