XVII] AFRICAN PATHOGENIC TRYPANOSOMES 299 



B. Trypanosomes in which the flagellum does not become 

 free anteriorly. 



/Parasite distinctly dimorphic . . =dimorphon, Laveran and Mesnil. 

 \ Parasite monomorphic . . . . Q >I ,-' = 2 



f Monkeys, dogs, rabbits, etc., refractory to infection =nanum, Laveran. 

 Monkeys and goats susceptible ; dogs, rabbits, etc., refractory to infection 

 = simi(B, Bruce, Harvey, Hamerton, Davey, and Lady Bruce *. 

 I Monkeys, dogs, rabbits, etc., susceptible to infection 

 _ / congolense, Broden. 

 ~ \pecorum, Bruce, Hamerton, Bateman, and Mackie. 



The latter two species are distinguished by cross immunity reactions. In 

 addition T. pecorum is more virulent than T. congolense. 



C. Trypanosomes having forms with a free flagellum and 

 forms without a free flagellum. 



/Trypanosomes immobilised by human serum . . =pecaudi, Laveran. 

 \Trypanosomesunaffectedbyhumanserum .. .. .. =2 



fin rats, trypanosome shewing a variable proportion of forms with the 

 trophonucleus at the posterior end of the body 



= rhodesiense, Stephens and Fantham. 



I Trypanosomes never shewing any posterior nuclear forms 

 I =gambiense, Dutton. 



* In this species the extreme tip of the flagellum may sometimes become 

 free for a length of 2-3 microns. 



REFERENCES. 



Laveran and Mesnil (1912). Trypanosomes et Trypanosomiases , 2nd 

 edition. MassonetCie. Paris. (Contains a very complete account 

 of the literature on the subject.) 



