4-8 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 
