Chap. 31.] Stomach of the Lolfter, &j. 



rejecting another. Birds have alfo an evident inftinct 

 even to diftinguiih one kind of earth from another, as 

 may eafily be Teen in Canary birds j the hen, at the 

 time of her laying her eggs, requires a quantity of cal- 

 careous earth, otherwife fhe is frequently killed by the 

 eggs not pafling forward properly, as I have in many 

 inftances oblerved > to one fet of hens a piece of old 

 mortar was given, which they broke down and fwal- 

 lowed, certainly not miftaking it for Canary feed, or 

 any kind of food, but diftinguiihing it from a piece of 

 brick, which they did not either break down or ("wal- 

 low -, another fet at the fame time were kept without; 

 any calcareous earth ; many of thefe died, while the 

 others, although otherwife exactly in the fame circum- 

 flances, were none of them loft. It appears therefore 

 that birds have a neceffity for (tones being fwallowed 

 for digeftion, and earths for ether purpofes, and that 

 they have an inftinft which dilpofes them to choofe the 

 proper quantity and quality required. Moreover, as 

 Mr. Hunter obferves, the noife of the grinding may be 

 heard, and therefore there can be no doubt that this 

 ftomach is made to contain Hones for the fame pur* 

 pofes for which teeth are employed *.' 



The lobfter is furnilhed, for the comminution of 

 its food, with an apparatus which is fituated at the 

 pylorus. It confifts of two bony furfaces, formed into 

 ridges, which are applied to each other like thofe of 

 the molares. They are alfo' covered, like our teeth, 

 with enamel, and furnifhed with mufcles, by which the 

 action of -grinding is performed. 



In order to difcover the power of the gizzard, 

 Reaumur gave to a turkey fmall tubes of glafs, five 

 lines in length and four in diameter; thefe were 

 broken in' the gizzard in twenty-four hours. In the 

 place of glafs tubes he fubftituted tubes, of tinned 



* Fordyce on Digeftion, p. 24, &c. 



iron, 



