XXVI 
FLIES AND SLEEPING SICKNESS 
3^3 
or nose, and examined under the microscope, the minute 
wriggling parasite will be seen in the field. Careful 
observations also show that though the parasites swarm 
in the blood this is not their only, or, indeed their chief, 
habitat, but they occur in the lymph glands and the 
cerebro-spinal fluid. It was in this fluid that Castellani 
discovered them and laid the real foundations of our 
knowledge of the pathology of sleeping sickness. The 
chief lesions which lead to the fatal termination of 
trypanosomiasis and which secured for it the name 
Trypanosomes (highly magnified). 
sleeping sickness are associated with the membranes and 
superficial strata of the brain and spinal cord. For 
these facts we are indebted to the careful work of Mott. 
Having discovered that sleeping sickness was caused 
by trypanosomes, the next and most obvious step was to 
find out how the parasites obtained access to the bodies 
of men and women. It has already been mentioned 
that the early exploration of the interior of Africa was 
seriously hampered by the fact that transport animals 
acquired a disease due to the bite of a fly which was 
particularly fatal to horses, donkeys, and dogs. Bruce 
Y 2 
