322 
EASTERN ETHIOPIA 
XXVI 
Usoga and along the east side of the lake to Kisumu. 
It spread to, and practically depopulated, the islands of 
the Sesse and the Buvuma Archipelagoes, and the 
lacustrine districts in the German sphere of interest. 
In Uganda it is very prevalent and no age is exempt. 
Race plays no important part, for many Europeans 
have contracted the disease. 
For a long time Sleeping Sickness baffled all attempts 
to determine its cause, but in 1902 Castellani examined 
the cerebro-spinal fluid from patients with this disease 
for organisms and detected the presence of trypano¬ 
somes in this fluid. This discovery was confirmed by 
Sir David Bruce, and Drs. Nabarro and Greig. 
The trypanosome is a protozoan parasitic in the blood 
of vertebrate animals. It lives freely in the serum of 
the blood, never within or attached to blood corpuscles, 
and possesses an undulating membrane which runs 
down one side of its more or less spindle-shaped body. 
At, or near, one extremity of the trypanosome is placed 
the blepharoplast, and from this structure, or in its 
immediate vicinity, the flagellum takes origin and runs 
along the free edge of the undulating membrane to 
the opposite end of the body, where it continues its 
course as a free flagellum. 
When these parasites obtain an entrance into the 
bodies of men, certain mammals, and birds, they 
flourish, multiply, and, certainly in the case of man, 
disturb the health : in the majority of instances they 
destroy life. Infection by these parasites is termed 
trypanosomiasis. So far as we know the chief disease 
resulting from their presence in the blood of man is 
known as Sleeping Sickness, or Negro Lethargy. The 
Baganda call the disease Kubongota “ to nod.” The 
species more particularly connected with man is known 
as T. gamhieiise. When tliese parasites colonise the blood 
they are carried in this medium through the “ natural 
gates and alleys of the body” so that when blood is 
extracted either from the trunk, the tip of the toe, finger, 
