EXPERIMENTS ON A CAGED CROW. 25 



until nearly twenty-four hours later that the teeth of the white-footed 

 mouse were ejected. Experiments made with various other articles of 

 diet containing hard parts showed conclusively that although the indi- 

 gesta were commonly disgorged in from one to four hours after eating, 

 some pieces were often retained for twenty-four hours or even longer, 

 and from the presence in Crow stomachs of bits of much worn bone, or 

 of seeds worn smooth by constant attrition, it seems certain that such 

 things are sometimes kept for even longer periods. It should be stated 

 farther that on several occasions well -grown mice were fed to the same 

 Crow, and the pellets subsequently disgorged showed no trace of bones, 

 but consisted solely of hair, teeth, and the inevitable sand. There is 

 no reason to doubt that the bones were ground up in the stomach and 

 completely digested. 



The amount of sand or gravel taken by an average Crow during cold 

 weather is almost beyond belief. When fresh sand was put into the 

 cage of the Crow he would put his head down close to the sand, turn 

 his bill sideways and half open, and swallow, time after time, all that 

 his bill would hold. In this way he frequently took the equivalent of 

 three or four tea-spoonfuls of clear sand in less than a minute, washing 

 it down immediately with copious drafts of water. After witnessing 

 this a few times, and finding that it was repeated at intervals all 

 through the day, usually soon after eating, the thick deposit of sand 

 and gravel which always occurs at Crow roosts was easily accounted for. 



