100 



ANIMAL FUNCTIONS. 



282. Grinding Apparatus of the Lobster. This part in 

 the lobster is represented Fig 72 



by Fig. 72, which shows 

 the inside of the stomach, 

 together with the tritura- - 

 ting machinery at its en- 

 trance. There is a carti- 

 laginous frame-work, in 

 which the hard calcareous 

 bodies marked a, 6, and c, 

 are implanted. These have 

 the form, and perform the 

 office of teeth. The tooth, a, is situated in the middle of 

 this frame ; it has a conical rounded shape, and is small- 

 er than the others, b and c, are of the same size and 

 shape. 



283. When these three teeth are brought together by 

 the action of the surrounding muscles, they exactly fit into 

 each other, and are capable by the motion which is given 

 them, of completely pulverizing the small shells of mollus- 

 ca, which have been introduced into the cavity of the 

 stomach as food. 



284. Grinding Apparatus of Birds. But the internal 

 machinery for grinding is larger, and more completely 

 formed in the granivorous, or grain-eating birds, than in 

 any other animal. In carnivorous birds, as the owl and 

 eagle, this part is entirely wanting ; but is found in all the 

 tribes which live on the seeds of vegetables, as the hen, 

 goose, pigeon, swan, &c. In proper with the ancient no- 

 tion, that " every part helps a part," the grinding faces of 

 the gizzard are dried, ground, and taken to help digestion 

 to this day. 



285. This organ, called the gizzard, has, in its structure 

 and mode of action, some analogy to the corn-mill. It 

 consists of two powerful muscles of a hemispherical shape, 

 with their flat sides applied to each other, and their edges 

 united by a strong tendon which leaves an oval, vacant 



Describe the triturating machine in the stomach of the lobster. Wha 

 tribes of birds are furnished with gizzards ? 



