343 
Encystation of E. grayi. —In the hind gut of one 
glossina Minchin found trypanosomes becoming 
encysted. The flagellum was withdrawn and absorbed, 
and the body then became surrounded by a definite 
cyst. 
With regard to the further development of a 
trypanosome taken into the stomach of a fly, several 
cycles are^ possible :— 
(1) It may develop in the fly and pass out through 
the proboscis as the malaria parasite does—this Minchin 
calls the inoculative cycle. 
(2) It may become encysted in the gut and pass 
out in the faeces, to be swallowed by another host. 
From the gut of this second host it may pass into the 
blood stream. This is the contaminative cycle. To 
what extent this occurs with any trypanosome, is at 
present unknown. 
(2) E. tullochi. —It resembles E. gambiense. The 
nucleus is rounded near the middle of the body, the 
blepharoplast is circular. 
These trypanosomes, natural to the fly, can be 
distinguished from E. gambiense (i) by their far greater 
activity, (ii) by their morphology, (iii) by adding a little 
goat’s serum ; the fly trypanosomes rapidly become 
immobile, whereas E. gambiense is uninfluenced. 
According to Koch, E. gambiense can occur in 
the salivary glands of Glossinae. 
2. E. brucei. —The cause of Ngana. This fatal 
disease or its varieties is widely spread throughout 
Africa. It occurs in horses, cattle, mules, and many 
other animals, excepting man. (The ‘ Jinja ’ cattle 
trypanosome of Uganda is probably the same as this). 
Symptoms. —(1) Remittent fever, (2) oedema vari¬ 
able in extent and sometimes fugitive in character, 
frequently affecting the belly and genitalia. (3) 
