DIGESTION OP BIKD9. 



55 



faces, the mill-stones, the intestine receiving the grain 

 in its divided state. It is a mill too, which acts with no 

 ordinary power, as you have seen in the case of the 

 ostrich. Spallanzani, the Italian physiologist, whose 

 bold and ingenious experiments often astonish while 

 they convince the reader, has published on this subject 

 sorhe very curious and interesting facts. He found that 

 balls of glass, and other brittle substances, when swal- 

 lowed by some of our domestic fowls, were speedily re- 

 duced to powder. Tubes of tin-plate were also found 

 to be crushed and broken down. Several leaden balls, 

 each furnished with twelve sharp needles, the points of 

 which projected one fourth of an inch beyond the sur- 

 face, were introduced into the stomach of a turkey and 

 common fowl. At the end of a day and a half, the ani- 

 mals being opened, the needles were observed to be 

 broken off close to the surface of the ball. In another 

 experiment, he forced down the throat of a turkey, a 

 leaden ball armed with twelve sharp lancets. The crea- 

 ture betrayed DO uneasiness, and being opened eight 

 hours after, the lancets were gone, leaving nothing but 

 the naked ball which presented some marks of impres- 

 sions. The coats of the stomach in all these cases were 

 perfectly unhurt. 



Emily. Our common fowls seem to manifest a strik- 

 ing fondness for such indigestible materials, for I have 

 frequently seen them swallow pebbles, and it is a com- 

 mon notion that they do not thrive when prevented from 

 obtain ing them. 



Dr. B. In these animals, they are undoubtedly es- 

 sential to healthy digestion. The quantity that is some- 

 times found in them is truly astonishing. Two hundred 

 have been found in a turkey- hen, and a thousand have 

 been taken from the stomach of a single goose. But 

 we must return to the food which we left changed into 

 chyme. 



Emily. You have not yet told what change liquids 

 ondergo when introduced into the stomach. The gas- 



