122 
BIG GAME AND TSETSE FLIES 
of reptilia and upon certain vegetable juices — such as that of 
sugar cane. 
3. The trypanosome of the disease nagana has been proved 
to be present in a large variety of warm-blooded animals. Its 
occurrence is not limited to the blood of any particular genera. 
The theory is sometimes held that it occurs in the blood of the 
kudu and the eland, but not in that of the bushbuck, the 
situtunga, or the inyala. This has been proved untenable. 
It is, of course, present in the blood of cattle, horses, sheep, 
goats, donkeys, and dogs infected with the disease, and from 
such may be conveyed by Glossina morsitans and G. pallipedes , 
or by inoculation, to other susceptible animals. 
4. Vegetation of large growth, giving a certain degree of 
shade, is necessary to the existence of the Glossina , and there is 
evidence to show that vegetation of a specialised character is 
particularly attractive to it. It has repeatedly been observed 
that the fly will not follow game into any large tract of country 
which is free from bush. It is not yet clear whether any 
particular class of vegetation is actually essential to the presence 
of Glossina morsitans and Glossina pallipedes. 
5. The absolute extermination (if such be possible) of large 
and small warm-blooded animals in a district where the climatic 
conditions favour the presence of tsetse fly will not avail to 
render such a district habitable by warm-blooded domesticated 
animals. Where the natural conditions favour the presence 
of tsetse flies they will be present even though the wild animals 
have been exterminated and replaced by domesticated animals. 
The result of such extermination would, so far as making the 
district habitable by domesticated animals, be absolutely nil. 
This has been shown by actual occurrence. 
6. The migratory habit of the fly is well known. Instances 
are on record of the fly abandoning a district where game was 
plentiful and returning to it after a lapse of several years. In 
the Eastern Transvaal one such area was regarded as so com- 
pletely and finally abandoned that farmers brought into it a 
large number of cattle. The fly reappeared, and immediately 
infected the cattle with nagana , with the result that most, if 
not all, died within a short space of time (Messrs. Hudson and 
Vaughan-Kirby). 
