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that of any other bone of the body ; while the 

 muscles attached to it weigh more than all the 

 other muscles of the body put together ! Let us 

 compare with these the sternum and pectoral 

 muscles of man, in relation to the rest of his bones 

 and muscles, and learn to be contented with the 

 functions to which our structure is adapted. 



Turning from this to another function, I have 

 to remark, that many birds have a mode of tri- 

 turating their food, distinct from those employed 

 by most other animals. In the latter, this is ef- 

 fected by the teeth, which birds do not possess ; 

 and, therefore, it was necessary that other means 

 should be provided for them, of tearing and des- 

 troying the texture of their aliment, in order to 

 expose all parts of it to the action of the fluids 

 poured into the stomach, and thus to render it 

 fit to nourish and repair the body. The organ 

 for effecting this purpose is the gizzard, an im- 

 mensely strong hollow muscle, lined with a sub- 

 stance so thick and callous, as not to be hurt even 

 by grinding down glass, and always found to con- 

 tain small stones, or the hardest materials the 

 bird can procure. By the help of these stones, 

 and by means of the hard internal coat of the 

 gizzard, and its muscular force, the food is ef- 

 fectually ground down, and fitted for the offices 

 assigned to it. Spallanzani, arid others, have 

 denied that such is the use of these stones, and 

 have affirmed that they were picked up by mere 

 accident, the animals mistaking them for seeds. 

 This supposition, however, is easily disproved by 



2 n 



