NATURAL ENEMIES 71 



of a single stout filament. In this stage it elongates 

 and divides later by simple longitudinal division. In 

 the postflagellate stage the organism shortens in length 

 and eventually loses its filament. 



Whether the presence of these intestinal parasites 

 affects the vitality of the fly is not mentioned, nor is it 

 understood whether they can be transmitted to any 

 other animal. 



Since the typhoid fly does not bite, it seems likely 

 that such a transfer does not take place. It is inter- 

 esting to note, however, that a parasitic flagellate of 

 the same genus, namely, Herpetomonas donovani, is 

 the causative organism of the tropical disease known 

 as kala azar, characterized by an enlargement of the 

 spleen, by irregularly recurrent fevers, anaemia and 

 emaciation, usually resulting in death, and that Cap- 

 tain Patton has discovered that the same parasite un- 

 dergoes a transformation in the intestine of a bedbug 

 (Cimex rotundatus) in India, confirming a suggestion 

 made with reasons by L. Rogers, who had previously 

 discovered the flagellated stage of the parasite. When 

 the blood of a kala azar patient is sucked into the ali- 

 mentary canal of the bedbug the parasites are liberated 

 by the digestive process and begin to develop from 

 the second to the fifth day. There is no evidence that 

 the bedbugs are infected except from human beings, 

 and there is no scientific proof that human victims ac- 

 quire the disease from the bugs. 



Another flagellate genus, Crithidia, is found in the 

 intestinal tract of certain flies, and one of them has 



