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 c 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. T. 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., 

 (i) 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. Parasitesare 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 

 T. brucei and T. evansi, state that T. brucei is shorter 

 and more compact than T. evansi. The movements of 



