THE GENUS TRYPANOSOMA 



265 



life was a second English sacrifice to this end, and his own obser- 

 vations, together with those of Todd, Koch, Brumpt, Greig, Gray, 

 Minchin, Nabarro, and a host of others, have made Trypanosoma 

 gambiense one of the best known of all mammalian trypanosomes. 



In the meantime other students of the protozoa were showing the 

 connections between different species of vertebrate trypanosomes and 

 invertebrate transmitting forms, so that today not only biting flies, but 

 mosquitoes, lice, and leeches are known to carry trypanosomes from 

 one vertebrate host to another, while only one case of direct trans- 

 mission from animal to animal has been demonstrated. This is of 

 considerable interest, as showing the power of trypanosomes to pene- 

 trate membranes, the organism Trypanosoma equiperduni being trans- 



FlG. 104 



A tsetse fly (Glossina longipeanis, Corti, from Somaliland) in resting attitude, showing 

 position of wings. (X3^-.) 



mitted by coitus, and thus giving rise to the disease dourine or mal 

 de coit. Koch and Doflein ('09) suggest that sleeping sickness may 

 be transmitted in the same way. 



Very great importance attaches to the happenings within the body 

 of the blood-sucking host, and here the matter is still in the whirl of 

 controversy. Bruce states that in the hundreds of tsetse flies examined 

 by him he has never found different stages of the parasite in the diges- 

 tive tract and no indication whatsoever of migration into the body 

 cavity of the fly. He regards the fly as a mere passive carrier of the 

 protozoon, transmitting the disease during a limited period, by inocu- 

 lating the victim with trypanosomes adhering to the proboscis either 

 inside or out. In this he is supported by Koch, Moore and Breinl, 

 Novy, Roubaud, and a host of others, who note that the organisms 



