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 sleeping 

 sickness and death. 



Transmission by 

 bite of tsetse fly. 



f 



Trypemosomes 



in human blood causing 

 Trypanosome fever. 



Transmission by bite 

 Man Antelope , etc. of tsetse fly. 



Tsetse fly 



{T 



Forms in salivary glands 

 ready for re. infection. 

 (-203O" 1 day) 



Crltbidial forms in. 

 salivacy Q lands 

 (2, or v3 dgya later) 



Forms in mt 

 a/fer infective meal) 



FIG. 21. 



newly arrived form in 

 aauvary aland. 

 (12 th to .20 th days.) 



Lona slender forms In pnoventriculus. 

 Cabout I0 ih tol5 tk days) 



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 



