30 



To determine the length of time required for digestion, two 

 methods were used : first, feeding substances more or less inde- 

 structible, such as the eggs of the gypsy moth {Portlititria dispar), 

 and afterwards examining the excreta, to determine how soon the 

 eggs were dropped ; second, an examination of the stomachs of 

 the dead birds. Ten experiments 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 wlien the first eggs were dropped in the excreta averaged one 

 hour, twenty-nine minutes and forty-five seconds, or approximately 

 one and one-half hours. The minimum time was forty-eight min- 

 utes 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 which are more 

 readily digested, it will be seen that the digestion of the bird is 

 remarkably rapid. 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 showed the stomach to be quite full, but less 

 than fifty per cent of the contents were in a condition to be recog- 

 nized. These were more particularly the hard parts of the wings, 

 thoraces and legs. The strongly chitinized pronota and hind 

 femora of the grasshoppers offered the most resistance to the 

 digestive process. The other fifty per cent of the stomach con- 

 tents was so finely divided that one would hardly care to express 

 a positive opinion as to its identity. 



The second crow was killed thirty minutes after the close of the 

 feeding period, which lasted four minutes, in which time the bird 

 ate six crickets and eleven grasshoppers. Twenty-five per cent of 

 the stomach contents was unrecognizable. 



Mr. Kirkland, who made the examinations, says : " I think from 

 what we have seen that we would expect to find the stomach 

 emptied in about one to one and one-half hours." 



The softer or more liquid food must evidently be digested in a 

 very few minutes and rapidly assimilated. 



The Food of the Crow. 

 The investigation of the food of the crow, which was begun in 

 1885 by the direction of the ornithologist of the Department of 

 Agriculture, is by far the most important examination of this 

 bird's food ever undertaken. A preliminary statement of the re- 

 sults of an examination of ninety-eight stomachs (eighty-six of the 

 common crow and twelve of the fish crow) was published in the 

 annual report of the Department of Agriculture for 1888. 



