150 GROWTH AND FOOD OF ANIMALS. 



in the stomach of a turkey, the circular plates were driven in, 

 and some of the tubes were broken, some compressed, and 

 some distorted, in the most irregular manner." 



' These smooth substances, although violently acted upon, 

 could not injure the stomach, and Spallanzani was therefore 

 induced to try the effect of sharp bodies. He found that the 

 stomach of a cock in twenty-four hours broke off the angles 

 of a piece of rough, jagged glass, without laceration or wound 

 A leaden ball, into which twelve strong tin needles were firmly 

 fixed, with their points projecting ^ibout a quarter of an inch 

 from the surface, was then covered with a case of paper, and 

 forced down the throat of a turkey. The animal discovered 

 no symptoms of uneasiness, and at the end of a day and a 

 half, when the stomach was examined, the points of the twelve 

 needles were broken off close to the surface of the ball, ex- 

 cept two or three, which projected a little. Two of these 

 points were discovered among the food: the other ten had 

 probably passed out of the body. 



' In another experiment, still more cruel than this, twelve 

 small lancets were fixed, in a similar manner, into a leaden 

 ball, and forced down the throat of a turkey cock. After 

 eight hours, the stomach was opened, but nothing appeared ex- 

 cept the naked ball, the lancets having been broken to pieces. 

 The stomach itself was found perfectly sound and uninjured 

 in both these experiments. 



' It is common, in the gizzards of many birds, to find small 

 stones, which have been supposed to assist in breaking down 

 grain and other hard substances into small fragments, to pre- 

 pare the way for their digestion. Spallanzani has endeav- 

 ored to prove that the muscular action of the gizzard is* 

 equally powerful without the stones. In a number of pigeons 

 which he had led from the egg himself, so as to prevent them 

 from obtaining stones, he found that tin tubes, glass globules, 

 and fragments of broken glass, were acted upon in the same 

 way as in ordinary circumstances; and this happened also 

 without any laceration of the stomach. It is the opinion, 

 however, of the best physiologists, notwithstanding these ex- 

 periments, that stones are extremely useful in the comminu- 

 tion of grain, and other substances which constitute the food 

 of fowls, though not absolutely essential. 



'2. In stomachs of an intermediate kind, such as those of 

 crows, ravens, &c., the power and action of their coats upon 

 substances contained within them, were found to be greatly 

 inferior to those of the strong muscular stomachs. But little 



