XXVI 
FLIES AND SLEEPING SICKNESS 
Modern medical writers recognise the part played by 
flies in the dissemination of disease; they multiply 
upon organic refuse of every kind, and if the temperature 
be favourable for their development, refuse and dead 
animal bodies abundant, flies may become a plague. 
They lay their eggs in carcases at the very instant of 
death and the species of flies and beetles which infest 
dead bodies are so numerous that the phrase “ Fauna of 
Corpses ” is justified. Linnaeus is credited with the 
statement that three meat-flies by reason of their rapid 
multiplication would consume a dead horse quicker than 
a lion. Moses turned his Egyptian experience to good 
account, for he recognised the value of the prompt 
burial of organic refuse, and gave explicit instructions 
for the burial of excrement (Deut. xxiii. 12, 13). 
Apart from the irritation and annoyance caused by 
flies (and to this day Egypt is plagued with them), 
there are very serious diseases afflicting man and 
animals in which flies play a very active part. The 
one with which we are specially concerned is known as 
sleeping-sickness. 
The consideration of the stages by which knowledge 
has been gained concerning the part played by Tsetse 
hies in spreading this, at one time, mysterious disease 
is brimful of interest, and leads us to admire the energy 
of the skilful investigators who have devoted them- 
