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. 
When 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, 
