48 THE HOUSE FLY DISEASE CARRIER 



was surely one of the colors least visited, but on the 

 contrary azure was one of those most frequented. He 

 thinks that possibly after all it was only a chance, but 

 is of the opinion that Fe's observation should be the 

 basis of an experiment on a large scale with the same 

 ultramarine blue which he employed. It seems doubt- 

 ful, however, that a cold, hungry fly will be kept from 

 a warm, odoriferous kitchen by the bluest of blue col- 

 ors. 



Fly-specks 



Since, on account possibly of the simplicity of the 

 digestive processes just referred to, pathogenic bacteria 

 and other micro-organisms pass unchanged through 

 the alimentary canal of the typhoid fly, the question of 

 fly-specks becomes one of great importance. Every 

 casual observer knows that they are laid with great 

 frequency, and that when flies are abundant their 

 specks are to be found everywhere. Curiously enough, 

 few exact observations have been made upon the fre- 

 quency with which the fly deposits its excreta. Major 

 N. Faichnie, previously referred to, working in India, 

 found that when a fly is put in a clean paper box it passes 

 its excrement fifty times in twenty-four hours; that is 

 to say, about once every half hour; but he neglects to 

 state whether there was food in the box. Presumably 

 there was some food, and also presumably there was 

 not much of a semi-liquid character. Cobb (1910) 

 gives a table of the intervals between defecation of a 

 well-fed fly, together with notes on the spores in the 

 excreta. One naturally infers, from the title of the 



