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STRUCTURE, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY. 379 



their way into tlie ovaries, where they undergo autogamy 

 and infect the subsequent brood. 



In Madras Patton found that 100 per cent, of the flies were 

 infected with the flagellate ; Prowazek found it in 8 per cent, 

 of the flies at Rovigno. In the cold season in^the plains 

 (India) Lingard and Jennings (I.e.) found the flagellate in 

 less than 1 per cent, of the flies examined ; in the hills 

 (Himalayas), at an elevation of 7500 feet, the flagellates were 

 most numerous during the hottest season of the year, and 

 gradually decreased in number to October and November, 

 when none were discovered. 



One of the chief points of interest in connection with this 

 flagellate is its similarity to the " Leishmann-Donovan " 

 body, the parasite of kala-azar, as it was this resemblance 

 that prompted Eogers (1905) to suggest that the latter 

 parasite was a Herpetomonas, which I think Patton has 

 now conclusively proved to be the case, and he calls it 

 Herpetomonas donovani (Laveran and Mesnil). 



Crithidia Musca3-domestica3 Werner. 



This parasite has been recently described by Werner (1908), 

 who found it in the alimentary tracts of four out of eighty-two 

 flies. It measures 10-13 JJL in length, the length of the body 

 being 57 /u and the flagellum 5 6ju. As in other members 

 of the genus Crithidia, which is closely allied to Herpeto- 

 monas, the breadth of the body is great compared with the 

 length, and the kinetonucleus and trophonucleus are rather 

 close together. A short, staining, rod-like body lies between 

 the kiuetonucleus and the base of the flagellum. The flagellum 

 is single. Dividing forms undergoing longitudinal division 

 were frequently found. The kinetonucleus appears to divide 

 first, followed in succession by the flagellum and the tropho- 

 nucleus. Forms undergoing division and showing a single 

 trophonucleus and double kinetonucleus and flagellum were 

 also found. Cases occurred in which the fission began at the 



