CLASSIFICATION OF PATHOGENIC TRYPANOSOMES 523 



without flagellum, long thin forms with flagellum, and intermediate 

 forms). 



T. gainbiense. — Does not show posterior nucdear forms in small labora- 

 tory animals. 



Size: Length 13 to 32 microns (average 22-5 microns); breadth 1*5 

 to 3 microns. 



Pathogenicity: When established in laboratory animals, very virulent. 

 Much less virulent at first inoculation from man, but monkey most sus- 

 ceptible. 



T. brucei {T. rhodesiense, T. pecaudi). — Shows posterior nuclear forms 

 in small laboratory animals. 



Size: Length 12 to 35 microns (average 21 to 23 microns); breadth 

 1-5 to 3-5 microns. 



Pathogenicity: Very virulent for laboratory animals, even at first 

 inoculation from man or other naturally infected hosts. 



(6) Development in the stomach and proboscis of tsetse flies. Mono- 

 morphic trypanosomes with no flagellum. 



T. congolense {T. nanum, T. pecormn). — Size: Length 9 to 18 microns 

 (average 14 microns); breadth 2 to 3 microns. 



Pathogenicity: Virulent for all laboratory animals. After passage 

 through goat loses virulence for laboratory animals, and then resembles 

 the natural strain, T. naniwi, which is not inoculable to laboratory 

 animals. 



T. smiicB. — Size: Length 14 to 24 microns (average 18 microns); breadth 

 1 to 2-75 microns. 



Pathogenicity: Not inoculable to small laboratory animals, but highly 

 virulent for monkeys and goats. 



(c) Development in the proboscis only of tsetse flies. 



Monomorphic trypanosomes with flagellum and characteristic swollen 

 posterior end. 



T. vivax (T. cazalboui). — Size: Length 15-5 to 30-5 microns (average 

 25 microns); breadth 2 to 3 microns. 



Pathogenicity: Not inoculable to laboratory animals as a rule, though 

 rabbits have been infected. 



T. unif or 7ne.— Size: Length 12 to 19 microns (average 16 microns); 

 breadth 1-5 to 2-5 microns. 



Pathogenicity: Not inoculable to laboratory animals. 



T. caprcB.—^ize: Length 18 to 32 microns (average 25-5 microns); 

 breadth 1-75 to 4-25 microns. 



Pathogenicity: Not inoculable to laboratory animals. 



