THE ANIMAL CARRIERS OF DISEASES 



Remarks.— 'It has been known for many years that flies can 

 carry micro-organisms on their legs. In 1888 Celli proved that 

 flies, fed upon pure cultures of typhoid bacilli, were able to transmit 

 virulent bacilli with their, excrement. Early observations also 

 proved that flies were capable of transmitting cholera. In the 

 Spanish-American War, in the Army Concentration Camps of 1898, 

 flies were found to be spreaders of typhoid. Lime was sprinkled 

 on the faecal pits, and the flies on the soldiers' mess-table were 

 noticed to have their legs whitened with the lime. 



Fig. 469. — B.-EAT> OF Musca domestica Fig. 470. — Leg of Musca 



LiNN^us: Female. domestica. 



(After C. J. Martin.) (After C. J. Martin.) 



ch., Pseudo-tracheae. - 



The flies which breed in human excrement in America are: 

 (i) Musca domestica, house-fly; (2) Drosophila ampelophila, fruit- 

 fly; (3) Fannia canicularis, little house-fly; (4) F. hrevis, little 

 house-fly; (5) Stomoxys calcitrans, stable-fly; (6) Phora femorata ; 

 (7) Sarcophaga trivialis. 



Of these the most common are the house and the stable flies. 

 The house-fly is 98 per cent, of all flies infesting houses. 



In the Boer War of 1900-02 flies were held to be great spreaders 

 of typhoid. In 1902 a paper, entitled ' An Inquiry into the Influence 

 of Soil, Fabrics, and Flies in the Dissemination of Enteric Infec- 

 tion,' was published by Firth and Horrocks in the British Medical 

 Journal, and they showed that the ordinary house-fly {Musca 

 domestica) can convey enteric infective matter from excreta or 

 polluted materials, or objects on which they may walk, rest, or 



