236 LECTUKE IX. 



The muscular action of a fish's stomach consists of vermicular 

 contractions, creeping slowly in continuous succession from the cardia 

 to the pylorus ; and impressing a two-fold gyratory motion on the 

 contents : so that, while some portions are proceeding to the pylorus, 

 other portions are returning towards the cardia. More direct con- 

 strictive and dilative movements occur, with intervals of repose, at 

 both the orifices, the vital contraction being antagonised by pressure 

 from within. The pylorus has the power, very evidently, of con- 

 trolling that pressure, and only portions of completely comminuted 

 and digested food (chyme) are permitted to pass into the intestine. 

 The cardiac orifice appears to have less control over the contents of 

 the stomach ; coarser portions of the food from time to time return 

 into the oesophagus, and are brought again within the sphere of the 

 pharyngeal jaws, and subjected to their masticatory and commi- 

 nuting operations. The fishes which afford the best evidence of 

 this ruminating action are the Cyiwinoids, (Carp, Tench, Bream,) 

 caught after they have fed voraciously on the ground-bait previously 

 laid in their feeding haunts to ensure the angler good sport. A Carp 

 in this predicament, laid open, shows well and long the peristaltic 

 movements of the alimentary canal ; and the successive regurgitations 

 of the gastric contents produce actions of the pharyngeal jaws as 

 the half-bruised grains come into contact with them, and excite the 

 singular tumefaction and subsidence of the irritable palate, as portions 

 of the regurgitated food are pressed upon it. The Eel is, also, a 

 good subject for studying the movements of the stomach ; and, 

 besides at the cardiac and j)yloric orifices, the direct constrictive 

 action of the circular fibres may be seen in this fish at the beginning 

 of the short pyloric division ; regulating the passage of the food from 

 the long cardiac sac. These observations throw light on the functions 

 of the pharyngeal teeth in the predatory Fishes, (the Pike, for ex- 

 ample,) in which one sometimes finds a recently swallowed fish in the 

 stomach : it may show, for example, a few marks of the large mandi- 

 bular canine teeth ; but it has undergone no sub-division by the 

 pharyngeal rasp-teeth. It would seem, at first sight, that these took 

 no other part in the mechanical operations of digestion, than to aid 

 in the act of swallowing : the analogy, however, of the ruminant or 

 regurgitant function of the stomach of the Carp, suggests that the 

 phaiyngeal teeth take a more important share in digestion, and 

 indicates the nature of their operations. As the gelatinous integu- 

 ments and intermuscular aponeuroses of the swallowed fish are dis- 

 solved by the gastric juice, masses of the myocommata become 

 detached, and these fibrous portions are most probably carried by 

 the regurgitating power of the stomach to the pharyngeal teeth. 



