STOMACHS OF MAMMALIA. 



139 



gan. But in other cases, as we have already seen, the sto- 

 mach exhibits a division into two compartments by means 

 of a slight contraction; a condition which, as Sir E. Home 

 has remarked, is sometimes found as a temporary state of 

 the human stomach;* while, in other animals, it is the na- 

 tural and permanent conformation. The Rodentia furnish 

 many examples of this division of the cavity into two dis- 

 tinct portions, which exhibit even differences in their struc- 

 ture: this is seen in the Dormouse, (Fig. 306) the Beaver, 

 the Hare, the Rabbit, and the cape Hyrax, (Fig. 307.) The 

 first or cardiac portion is often lined with cuticle, while the 



306 



lower portion is not so lined; as is seen very conspicuously 

 in the stomachs of the Solipeda. The stomach of the Horse, 

 in particular, is furnished at the cardia, with a spiral fold of 

 the inner, or cuticular membrane, which forms a complete 

 valve, offering no impediment to the entrance of food 

 from the oesophagus, but obstructing the return of any part 

 of the contents of the stomach into that passage.! This 



* The figure given of tfte human stomach, p. 183, shows it in the state of 

 partial contraction here described. 



j- The total inability of a horse to vomit is probably a consequence of the 

 impediment presented by this valve. See Mem. du Museum d'Hist. Nat. viii. 

 111. 



