INSECTS AND HUMAN DISEASE 125 



into Malta harbour, buc without communicating with the 

 shore, the flies returned in greater force, and the cholera 

 also, with increased violence. After more cruising at sea, 

 the flies disappeared gradually, with the subsidence of the 

 disease/ Various experiments and observations in more 

 recent times, notably those of Macrae and Buchanan in 

 India and Tsuzuki in China, present convincing evidence 

 that the house fly plays an important part in the dis- 

 semination of cholera. 



"The earliest experiments with anthrax in relation to 

 flies are those of Raimbert (1869), who placed house flies 

 and meat flies on infected material and afterwards tore off 

 their appendages and inoculated them, with positive results, 

 into animals. Experiments of a somewhat similar nature 

 were made by Celli (1888), Sangree (1899), and Buchanan 

 (1907), and they 'all agree in demonstrating that flies pick 

 up anthrax bacilli when they walk about and feed on 

 infected material. It remains to be determined how long 

 flies may harbour the bacillus on its spores, and whether 

 the virulence of the bacillus in the vegetative stage i6 

 modified by passage through the intestines of flies.' 



"The part played by non-biting flies in the spread of 

 ophthalmia is well recognised to-day. Budd, as early as 

 1862, considered it was fully proven that flies serve as 

 carriers of Egyptian ophthalmia. Laveran (1880), writing 

 of Biskra, says the same. Howe (1888) stated that (1) 

 the number of cases increases rapidly from the moment 

 when flies are present in large numbers; (2) eye trouble 

 occurs in the same places where flies are numerous (Delta 

 of the Nile) ; where there are a few flies (the Desert) there 

 are also a few cases of illness ; (3) natives, and especially 

 children, are remarkably indifferent to the attacks of flies : 

 they allow the flies to settle in crowds about their eyes, 

 sucking the secretions, and never think of driving them 

 away; (4) examination of the flies captured on diseased 

 eyes revealed bacteria on their feet which were similar to 



