282 BOARD OF AGRICULTURE. [Pub. Doc. 



When fed less than eight ounces each they either did not in- 

 crease in weight or fell oft", and it was not until each crow 

 was fed ten or more ounces that their weight increased. If 

 the amount given the crows was largely reduced during any 

 one day there was a corresponding falling off in the weight 

 of the V)ird. On September 13 the larger crow weighed 

 eighteen and one-half ounces. On that day it was given 

 only two ounces of tomato, Hfty-six grasshoppers, twelve 

 crickets and a little grain, in all some three ounces of food. 

 The next morjiing it had lost one and one-half ounces in 

 weight. 



As a preliminary to the solution of some of the problems 

 which come up during stomach examinations, a knowledge 

 of the processes of digestion and their possibilities in the 

 species under consideration is indispensable. Crows swal- 

 low large quantities of sand, gravel, etc., to aid in the diges- 

 tive process. The muscular walls of the stomach contract 

 upon these hard substances, and thus the food is ground, 

 crushed and masticated, so to speak, in the stomach. 



To determine the length of time required for digestion, 

 two methods were used : first, feeding substances more or 

 less indestructible, such as the eggs of the gypsy moth 

 (^Porllieti'ia disjmr), and afterwards examining the excreta to 

 determine how soon the eggs were dropped ; second, an ex- 

 amination of the stomachs of the dead birds. Ten experi- 

 ments of the first class and two of the second were made 

 upon the two birds. 



From the time of the beginning of the feeding period to 

 the time when the first eggs were dropped in the excreta 

 averaged one hour, twenty-nine minutes and forty-five sec- 

 onds, or approximately one and one-half hours. The mini- 

 mum time was fort3-eight minutes and the maximum time 

 was an hour and fifty-four minutes. 



When we consider that the indigestible substances are 

 usually retained in the stomach much longer than those 

 w^hich are more readily digested, it will be seen that the di- 

 gestion of the bird is remarkably raj)id. The crow which 

 was accidentally killed had fed freely upon grasshoppers for 

 twenty minutes, and was killed ten minutes after the close of 

 the feeding period. An examination of the alimentary canal 



