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 ffuid causing 3(eepin0 

 sickness and death. 



Transmission by 

 bite of tsetse fly. 



t 



Trypanosomea 



in human Wood causing 

 Trypanosome fcver- 



Transmission by bite 

 Man. Antelope, efc. of tsetse fly. 



Forms in salivary glands 

 ready for re- infection. 

 \20"--30"' diay) 



Tsetse riy 



Crithidial forms in. 

 salivacv slands 

 (s. or o days later) 



Forms in midgut,CVS/i 

 after infective meal}. 



newly arrived form in 

 3a(ivary aland. 

 lia^-toJofl-doys.! 



Long slender fbrms In proventriculus. 

 f about I0"'tol5«''days) 



Fig. 21. Life History of Trypanosoma gamhiense. x 1500. (Constructed 

 from figures by Miss Robertson.) 



which very closely resemble the parasites in vertebrate blood 

 (Fig. 21E) 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 



