STRUCTURE, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY. 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 pi’ison 
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 faeces of the flies. He 
concludes that these insects may act as disseminators of 
cholera. During a cholera epidemic Tizzoni and Cattaui 
(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 sjiirillum. 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 
