345 
principally, but also by Gl. palpalis (?) and Gl. palli- 
dipes (?). 
The fly, after biting, remains infective from 
twelve to forty-eight hours, but not longer. It is 
possible, however, that it may become infective again 
much later. It has been known since Livingstone’s 
time that horses and cattle become diseased after 
passing through a 6 fly-belt.’ The flies transmit the 
trypanosomes which exist in the wild game. Trypano¬ 
somes have been found in wildebeest, kudu, bushbuck, 
etc. ; the wild game, though infected, are apparently 
healthy. Cattle and other animals suffering from a 
chronic form of the disease also give a constant supply. 
Cultivation. —Is difficult at first, but sub-cultures 
grow well and are fully virulent. 
3. E. evansi. —The cause of Surra and its varieties. 
It is known in India, Burma, Indo-China, Java, the 
Philippines, Mauritius, and the varieties in N. Africa. 
It occurs naturally in horses, mules, camels, etc. 
Cattle, as a rule, enjoy considerable immunity, yet 
in the outbreak in Mauritius twenty-five to one 
hundred per cent. died. 
Symptoms. —Are similar to those of Ngana, viz., 
(1) remittent fever, (2) progressive anaemia and 
emaciation, (3) oedema, (4) discharge from the nostrils 
and eyes, (5) muscular weakness and paralysis. Death 
occurs in some days, weeks, or even months. 
Blood Examination. —Parasites are found frequently 
with difficulty. They are particularly scanty during 
periods of apyrexia. Make a subinoculation in doubt¬ 
ful cases. 
Morphology. — 22-30/^ in rats, 35/* in horses. 
Laveran and Mesnil, who have made a comparison of 
E. brucei and E. evansi , state that E. hrucei is shorter 
and more compact than E . evansi. The movements of 
