FLY TRANSMISSION. 65 



ganisms, after ingestion by the fly, then multi- 

 plied, and were deposited in larger numbers in 

 fly-specks. It is, indeed, a difficult point to deter- 

 mine whether or not proliferation of these micro- 

 organisms actually takes place in the intestines of 

 the fly. Observations by Spillman and Haushalter, 

 Hofmann, Celli, Hayward, Lord and others have 

 shown conclusively that house-flies ingest tubercle 

 bacilli from the sputum of patients and excrete 

 them in their feces. The observations of Lord 1 

 suggest, but do not actually prove, that the bacilli 

 multiply in the intestines. It has been demon- 

 strated several times, by inoculation into guinea- 

 pigs, that the bacilli in the fly-specks are virulent. 

 The specks dry quickly and there is little danger 

 of the organisms taking part in dust infection un- 

 less the specks are violently dislodged, and they 

 die in a few days. On the other hand, there may 

 be a real danger from the deposition of the specks 

 on food (Lord), which suggests a point in pro- 

 phylaxis. 



Similar questions are raised also in the relation 

 of the fly to typhoid, cholera, dysentery and plague. 

 The importance of the fly in the mechanical dis- 

 semination of typhoid bacilli, resulting in exten- 

 sion of epidemics, is now well established, as illus- 

 trated by the observations of Alice Hamilton, and 

 the inquir} 7 " into the prevalence of typhoid fever 

 in the American troops during the Spanish- Amer- 

 ican war. The conditions are similar in relation 

 to cholera. Concerning dysentery it is considered 

 probable that flies are a factor in distribution, al- 

 though the point has not been positively demon- 

 strated. It is uncertain whether the organisms of 



1. Reports of the Massachusetts General Hospital. 



