PATHOGENIC TRYPANOSOMES IN TSETSE FLIES 



515 



Identification of Trypanosomes in Tsetse Flies. — As various pathogenic 

 trypanosomes undergo development in tsetse flies, it is of importance 

 to be able to identify them. Most observers have adopted the method 

 of identifying the trypanosomes which appear in animals after the flies 

 have been allowed to feed upon them. This is a laborious method which 

 entails considerable delay. Though it has been possible in many cases to 



Salivary glands. No phase. 



Hypopharynx. Preinfective forms 

 enter and become infective- In- 

 fective forms accumulate. 



Labial cavity. Only phase of 

 mill tiplicati on . Compact 



colonies of fusiform crithidia, 

 long free flagellum, produc- 

 ing free-flagelljte posterior- 

 nuclear preinfective forms. 



Mid gut. No phase. Blood forms 

 which enter disintegrate. 



Fig. 219. 



-Diagnostic Characters of Tnipanosoma vivax in the Tsetse Fly. 

 (After Lloyd and Johnson, 1925.) 



Salivary glands. No phase. 



Labial cavity 

 No phase. 



Mid gut. Only phase of multiplica- 

 tion. Large free-flagellated undu- 

 lant crithidia, long slender crithidia, 

 short - flagellated trypanosomes. 

 Complete life history not known. 



Fig. 220.— Diagnostic Characters of Trypanosoma grayi in the Tsetse Fly. 

 (After Lloyd and Johnson, 1925.) 



make a shrewd guess as to the species from what is known of the site of 

 development in the fly, there has been no certainty about the identification 

 apart from the trypanosomes of the polymorphic type (T. brucei, T. gam- 

 ble nse), which are known to be the only ones which invade the salivary 

 glands. Lloyd and Johnson (1924). however, after a careful study of the 



