HABITS OF THE ADULT FLY 
51 
warm incubator. He fed three lots of flies on syrup, 
milk, and sputum, respectively, for several days, and 
noted that those fed on syrup produced an average of 
four and seven-tenths deposits per fly per day, those 
on milk eight and three-tenths and those fed on sputum 
twenty-seven. In the latter case he states that the feces 
were much more abundant and liquid than usual, and 
that in fact the flies seemed to suffer from diarrhea. 
In another series of experiments ten flies were given 
a single feed of milk and then transferred to fresh 
cages. They deposited either by regurgitation or as 
excrement forty-one spots in the first hour, sixteen in 
the second and third, twenty-four in the fourth, twenty- 
four in the fifth, and fifty-nine in the prolonged inter¬ 
val between the sixth and twenty-second hour. With 
another series of eleven flies, milk was always present 
in the cage so that the flies could feed as often as they 
wished, and here thirty-two spots were made in the 
first hour, forty in the second and third, ten in the 
fourth, eighteen in the fifth, and 134 in the sixth to 
the twenty-second hour; making a total of 164 spots 
from the ten flies that had had but one feeding and 
224 from the eleven flies which had the milk contin¬ 
uously in their cage. 
Distance of Flight 
Prof. S. P. Langley, the late Secretary of the Smith¬ 
sonian Institution, was, as every one knows, greatly 
interested in the problem of aeronautics, and his ex¬ 
periments with flying machines heavier than air prac- 
