2l8 TROPICAL MEDICINE AND HYGIENE 



trypanosomes are present, they can if they rapidly com- 

 plete their feed on a second person infect him with 

 trypanosomes. The more important method of convey- 

 ance is after a sufficient interval for the parasites to 

 develop and in the developed form to pass into the 

 proboscis. Some flies, as the Hippoboscidce, are truly 

 pupiparous, as they deposit the pupa and not larvas. 



Some of the important Orthorrhaphous flies deposit 

 eggs on vegetation at the edge of water or in the water 

 itself, as in Tabanus and Chrysops. The larvas which 

 hatch out are aquatic or semi-aquatic, living in wet sand 

 or earth, and the flies may, as in the case of Chrysops 

 dimidiate and Filaria loa, act as alternative hosts of 

 parasites, but we do not know so far if they act as 

 porters of disease. This action is not likely in these 

 instances to be important. 



For fuller information as regards " flies " the reader is 

 advised to study " Entomology for Medical Officers," by 

 A. Alcock, C.I.E., M.B., LL.D., F.R.S., Indian Medical 

 Service (retired), Lecturer on Medical Entomology, &c., 

 at the London School of Tropical Medicine. Gurney 

 and Jackson, 33, Paternoster Row, London. 1911. Price 

 95. net. 



