343 



Encystation of T. 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 The flagellum was withdrawn and absorbed, 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) T. tullochi. It resembles T. 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 T. 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 T. gambiense is uninfluenced. 



According to Koch, T. gambiense can occur in 

 the salivary glands of Glossinae. 



2. T. 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 c Jinja ' cattle 

 trypanosome of Uganda is probably the same as this). 



Symptoms. (i) Remittent fever, (2) oedema vari- 

 able in extent and sometimes fugitive in character, 

 frequently affecting the belly and genitalia. (3) 



