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STRUCTURE, DEVELOPMENT, AND BIONOMICS OF HOUSE-PLY. 397 



ance of the epidemics were coincident with the fly-season." 

 Buchanan (1897), in a description of a gaol epidemic of cholera 

 which occurred at Burdwan in June, 1896, states that swarms 

 of flies occurred about the prison, outside which there were a 

 number of huts containing cholera cases. Numbers of flies 

 were blown from the sides where the huts lay into the prison 

 enclosure, where they settled on the food of the prisoners. 

 Only those prisoners who were fed in the gaol enclosure 

 nearest the huts acquired cholera, the others remaining 

 healthy. 



Bacteriological evidence. Maddox (1885) appears to 

 have been the first to conduct experiments with a view to 

 demonstrating the ability of flies to carry the cholera spirillum, 

 or, as it was then called, the " comma-bacillus." He fed the 

 flies C. vomitoria and Eristalis tenax (the " drone-fly") 

 on pure and impure cultures of the spirillum, and appears to 

 have found the motile spirillum in the fasces of the flies. He 

 concludes that these insects may act as disseminators of 

 cholera. During a cholera epidemic Tizzoni and Cattani 

 (1886) showed experimentally that flies were able to carry the 

 " comma-bacillus" on their feet. They also obtained, in two 

 out of three experiments, the spirillum from cultures made 

 with flies from one of the cholera wards. Sawtchenko (1892) 

 made a number of careful experiments. Flies were fed on 

 bouillon culture of the cholera spirillum, and to be certain 

 that the subsequent results should not be vitiated by the 

 presence of the spirillum on the exterior of the flies, he dis- 

 infected them externally and then dissected out the alimentary 

 canal, with which he made cultures. In the case of flies 

 which had lived for forty-eight hours after feeding, the 

 second and third cultures represented pure cultures of the 

 cholera spirillum. Simmonds (1892) placed flies on a fresh 

 cholera intestine, and afterwards confined them from five to 

 forty-five minutes to a vessel in which they could fly about. 

 Boll cultures were then made, and colonies of the cholera 

 spirillum were obtained after forty-eight hours. Colonies 

 were also obtained from a fly one and a half hours after having 



