AFRICAN TRVPANOSOMIASIS 



125 



iMinchin considers that encysted forms from fly dropjDings may be 

 ingested and cause infection. 



It is fairly conclusive that Tabanides convey it mechanically from 

 beast to beast in herds of cattle. 



Race does not affect infection. 



Occupation predisposes in so far as there may be exposure to the 

 flies near their breeding- places or cover areas. Hence those working 

 along the shores of rivers and lakes of infected regions are exposed to 

 the bites of infected Glossinaj, usually palpalis, while porters marching 

 through the bush are exposed to the bites of G. morsitans. 



THE PARASITE. 



As seen in Jrcsli bluod the trypanosome is an active wriggling 

 organism with a laterally compressed spindle-shaped body, provided 

 with a delicate undulating membrane. Fringing the dorsal edge of 

 the trypanosome and terminating in a free whip-like filament is the 

 flagellum. 



Stained specimens show a 

 nucleus, somewhat central, and a 

 minute deeply staining chromatic 

 mass, the blepharoplast, which is 

 nearer to one pole, e.g., the 

 thicker or aflagellum or anterior 

 end of the organism. Near to 

 the blepharoplast is a small non- 

 staining area, viz., the vacuole. 

 The thickened free border of the 

 undulating membrane springs 

 from the blepharoplast at one 

 end, and is continued as the 

 flagellum at the other. 



In some places the cytoplasm is homogeneous, while in others it is 

 faintly granular when stained. 



There is great diversion in the dimensions of the parasite in body, 

 nucleus and flagellum. 



Multiplication is bv longitudinal division, commencing at the 

 blepharoplast, which elongates and then divides. This is followed by 

 the duplication of the thickened margin of the undulating membrane 

 and longitudinal division of the whole body. The flagellum does not 

 divide. 



The complete separation of the two halves along the posterior 

 border does not take place until the new flagellum has been formed. 

 When separation takes place it is postero-anteriorly. 

 Sexual differences have not been decided upon. 



Trypanosoma gaiiibiense. 

 (After Dutton.) 



1,700. 



