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- 



