PATHOGENIC TRYPANOSOMES IN TSETSE FLIES 517 



Stomach.— T. brucei and T. gambiense : Trypanosomes of the blood 

 types which multiply and become transformed into long slender trypano- 

 somes with flagella. 



T. congolense : Trypanosomes of the blood type which multiply and 

 become transformed into long trypanosomes without flagella. 



T. vivax : Trypanosomes of the blood type which quickly degenerate. 



T. grmji : Long crithidia forms and long trypanosome forms with very 

 short flagella. 



Labial Cavity. — T. brucei and T. gambiense : Trypanosomes of the 

 blood type on their way to the stomach; long slender trypanosomes with 

 flagella which are passing from the stomach to the hypopharynx. 



T. congolense : Trypanosomes of the blood type on their way to the 

 stomach; long trypanosomes without flagella from the stomach; crithidia 

 forms without flagella. 



T. vivax : Trypanosomes of the blood type; crithidia forms with flagella. 



Hypopharynx. — T. brucei and T. gambiense : Long trypanosomes 

 with flagella on their way from the stomach and labial cavity to the salivary 

 glands; short stumpy metacyclic trypanosomes without flagella passing 

 from the salivary gland to the vertebrate. 



T. congolense : Crithidia forms without flagella from the labial cavity ; 

 metacyclic trypanosomes of the blood type. 



T. vivax : Crithidia forms from the hypopharynx; metacyclic trypano- 

 somes of the blood type. 



Salivary Gland. — T. brucei and T. gambiense : long slender trypano- 

 somes with flagella from the stomach; crithidia forms; short stumpy 

 metacyclic trypanosomes without flagella. 



There seems to be some doubt as to the path taken by trypanosomes 

 in their passage from the labial cavity to the hypopharynx. In the 

 diagrams given by Lloyd and Johnson (Figs. 217-220) they are represented 

 as passing through a slit in the wall of the hypopharynx. Authorities 

 are by no means agreed that such an opening exists. If the hypopharynx, 

 which is really a continuation of the salivary duct, is a closed tube, then 

 it must be supposed that the trypanosomes enter it at its open end at the 

 extremity of the proboscis. 



Experimentally Proved Vectors of Pathogenic Trypanosomes of Africa. 



Glossina brevipalpis: T. brucei, Bruce et al., 1914; Braun and Teichmann, 

 1914. T. congolense, Bruce et al., 1914; Braun and Teichmann, 1914. T. caprce, 

 Bruce et al, 1914. T. simice, Bruce et al, 1914 (dissection of flies only). 



Glossina fusca: T. gambiense, Ross (P. H.), 1908. TJndetermiyied, Greig, 1905 

 (? which fly). 



