6 INTRODUCTION 



these investigations were proceeding much more informa- 

 tion came to light. The transmission of yellow fever 

 by the Stegomyia gnat, the transmission of Sleeping 

 Sickness by tsetse flies, that of Dengue or Dandy 

 fever by mosquitos, and three-day fever by Phlebotomus 

 flies was established; the transmission of the blood- 

 worm disease or Elephantiasis by mosquitos is probable 

 also, though still open to experimental proof. 



According to Dr. L. O. Howard, however, Chief of 

 the United States Bureau of Entomology, to whose 

 book, " The House-fly, Disease Carrier " I am indebted 

 for considerable information, some researches had been 

 carried out as early as 1888 by Celli, who showed that 

 virulent tubercle bacilli were found in flies which 

 had fed on the spittle of consumptives, and typhoid 

 bacilli in flies fed on pure cultures of that bacillus ; and 

 these observations were confirmed by Hayward, Lord, 

 Buchanan. Buchanan also demonstrated anthrax bacilli 

 in the intestines of flies which had fed on carcasses 

 of animals dead of that disease. Yersin, of Plague- 

 antitoxin fame, in 1894 found many dead flies in his 

 laboratory at Hong Kong, in which there were several 

 animals that had died of plague. He inoculated the 

 juices of one of these dead flies into other animals, and 

 they also died of plague. Dr. Graham Smith, in his 

 Report to the Local Government Board, New Series, 

 No. 40, quoted by Howard, states that Simmons in 

 1892 found the germs of cholera in flies caught in a 

 cholera mortuary ; and Macrae in 1894 in India showed 

 (Nuttall, " Insects and Disease ") that flies " should be 

 considered as one of the most important agencies in 

 the diffusion of this disease." Tsuzuki in 1904 culti- 

 vated the germs from flies captured in houses wherein 

 cholera had occurred in China. Nuttall states that 



