i6o 



MARTIN FROBISHER, JR. 



In order to control the effects of starvation and drought on 

 these flies, twenty-nine normal specimens were placed in a dry 

 empty flask, ten in a flask containing nothing but a pledget of 

 cotton wetted with distilled water, and thirty-four in a vessel 

 containing sterile agar. The fate of these flies is shown in 



Table II. 



TABLE II. 



FATE OF FLIES UNDER CONDITIONS OF DROUGHT, STARVATION, ETC. 



1 Number varied because of activity of flies. 



2 No observation. 



It appears that the flies die very rapidly as a result of drought 

 and the absence of anything but water. The more prolonged 

 survival of the flies on the sterile agar may be attributed either 

 to an ability to metabolize this or its impurities or, more likely, 

 to an automatic inoculation of the agar with the yeasts on their 

 feet and in their feces. 



It appears to be shown by this experiment that the sterile 

 flies survive in cultures of mold beyond the period within which 

 it would be expected that they would die of drought or starvation 

 and it therefore seems logical to assume that they eat the mold, 

 but that the mold finally grows w r ithin them and kills them. 



Some of the dead flies were imbedded in paraffin within an 

 hour after death and serial section made. Such sections show 

 that the mold may actually invade the tissues of the fly. 



It should be noted that error due to variation in longevity of 

 the flies is probably nil, since: 



i. The flies were all young (10-15 days old) progeny of 

 standardized stock, originally furnished by Dr. Raymond Pearl, 

 and deaths in these experiments always occurred well within the 

 minimum of longevity. 



