100 



TRYPANOSOMES AND SLEEPING SICKNESS 



they attach themselves by their flagella (Fig. 2 ID) and, rapidly 

 multiplying, undergo a crithidial stage. As multiplication con- 

 tinues free-swimming trypanosome forms are again produced 



To cerebrospinal fluid causing steeping 

 sickness and death. 



Transmission by 

 bite of tsetse fly. 



Trypcmosomea 



in human blood causing 

 Trypcmpsome fevei* 



ransmisaion by bite 

 Man. Antelope , etc. I of tsetse fjy. 



Tsetse fly 



forms in salivary glands 

 ready for re- infection, 

 day) 



Crltbidfal forms in 

 salivary .glands 

 (.2 or a days later) 



iTrai 







Forms in midgur,(VS 

 a/ter infective meal). 



FIG. 21. 



newly arrived form in 

 aafivai 

 (12 th 



Lona Slender farms m proventriculus. 

 (about I0* h tol5 th day5) 



Life History of Trypanosoma gambiense. X 1500. 

 from figures by Miss Robertson.) 



(Constructed 



which very closely resemble the parasites in vertebrate blood 

 (Fig. 21 E) and which are now capable of infecting a vertebrate 

 host. The whole cycle in the fly usually occupies from 20 to 30 

 days. According to Kinghorn and Yorke the time required for 



