LIFE HISTORY 31 



and, if after this the fly continues to feed, the food 

 may pass directly into the true stomach through the 

 chyle stomach. If the fly is disturbed before any of 

 the food has entered the stomach, the food which has 

 been sucked into the crop is gradually passed into the 

 stomach. Eventually the contents of the crop get into 

 the intestine. The proventriculus seems to act also as 

 a valve and be capable of closing the orifice into the 

 stomach so that the food shall all pass into the crop. 

 \Yhen the crop is fully distended it opens so that food 

 can pass directly into the stomach, and naturally also 

 opens later to allow the food to pass from the crop 

 forward and back. 



Careful observations made by this author indicated 

 the rate at which food passes from the crop into the 

 intestine, in which he showed that, using colored fluid, 

 after three minutes the crop was full of red fluid, but 

 none was found in the stomach or intestine. After ten 

 minutes the fluid was just beginning to pass into the 

 stomach. After fifteen minutes the crop was still full 

 and the upper third of the stomach was full. After 

 two hours in one case the crop was still full and the 

 upper three-fourths of the intestine was full. Other 

 observations indicated that the crop may remain full, 

 after a single feeding, for as long as four days, thus 

 acting as a storage reservoir against any possible scar- 

 city of food. 



Some interesting observations were also made by the 

 same author on the habits of flies after feeding on dif- 

 ferent fluids. These observations were made in cages, 



