CHOLERA 175 



by fly infection, and thinks that the fly "should be considered as 

 one of the most important agencies in the difl"usion of the 

 disease." Buchanan describes a jail outbreak which occurred at 

 Burdwan in 1896. P'lies swarmed, and outside the prison were 

 some huts in which cholera prevailed. A strong wind blew 

 large numbers of flies from the direction of the huts into the 

 prison enclosure. Only those prisoners who were fed at the 

 jail enclosure nearest the huts acquired the disease, whilst all 

 the others remained healthy. 



It will be noticed that most of the observations quoted were 

 made more than ten years ago, when the methods of bacte- 

 riological diagnosis were less perfect. Consequently further 

 bacteriological investigation during cholera outbreaks is necessary 

 before the exact part played by flies in the spread of the disease 

 is ascertained, though the evidence at present available seems to 

 indicate that flies are often responsible for infecting food with 

 the vibrios. 



CHAPTER XVI 



TUBERCULOSIS 



Experiments. 



Spillman and Haushalter (1887) seem to have been the first 

 to investigate the possible relation of M. doniestica \.o the 

 dissemination of B. tuberculosis. They found tubercle bacilli 

 in the intestinal contents and faeces of flies which had fed on 

 tubercular sputum. Hofmann (1885) fed flies on tubercular 

 sputum and found the bacilli in their faeces. He also inoculated 

 three guinea-pigs with emulsions of the intestines of these flies, 

 and one of them developed tuberculosis. He found, however, 

 that fly faeces six to eight weeks old gave negative results on 

 inoculation. Celli (1888) reported on some experiments by 

 Alessi who inoculated the faeces of flies which had fed on 

 tubercular sputum into rabbits. Some of these animals de^ 

 veloped the disease. 



