140 



THE VITAL FUNCTIONS. 



valve is shown in Fig. 3 11, which represents an inner view 

 of the cardiac portion of the stomach of the horse; o being 

 the termination of the oesophagus. 



The stomach of the Water 



311 .^W^^^ Rat is compos ed of two dis- 



tinct cavities, having a narrow 

 passage of communication: 

 the first cavity is lined with 

 cuticle, and is evidently in- 

 tended for the maceration of 

 the food before it is submit- 

 ted to the agents which are to 

 effect its digestion; a process 

 which is completed in the se- 

 cond cavity, provided, for that 

 purpose, with a glandular sur- 

 face. 



In proportion as nature allows of greater latitude in diet, we 

 find her providing great complication in the digestive appara- 

 tus, and subdividing the stomach into a greater number of ca- 

 vities, each having probably a separate office assigned to it, 

 though concurring in one general effect. A gradation in this 

 respect may be traced through a long line of quadrupeds, 

 such as the Hog, the Peccari, the Porcupine, (Fig. 308,) and 

 the Hippopotamus, where we find the number of separate 

 pouches for digestion amounting to four or five. Next to 

 these we may rank the very irregular stomach of the Kan- 

 guroo, (Fig. 309) composed of a multitude of cells, in which 

 the food probably goes through several preparatory processes: 

 and still greater complication is exhibited by the stomachs 

 of the Cetacea, as, for example, in that of the Porpus (Fig. 

 310.) As the fishes upon which this animal feeds are swal- 

 lowed whole, and have large sharp bones, which would injure 

 any surface not defended by cuticle, receptacles are provided, 

 in which they may be softened and dissolved, and even con- 

 verted into nourishment, by themselves, and without inter- 

 fering with the digestion of the soft parts. The narrow com- 



