ORGANS OF DIGESTION. 117 



ble of holding about three pints, when moderately dis- 

 tended. As already stated, under Fig. 74, a, is the 



Fig. 79. 



g 



esophagus, or passage from the mouth ; 6, the cardiac 

 portion ; c, the left extremity ; d, the small extremity ; 

 and e, the pylorus, tied ; g g, the omentum, or caul, 

 which is attached to the outside of the stomach, and 

 falls down from it like a curtain. 



Gastric Juice. The chief agent concerned in diges- 

 tion is the Gastric Juice, as already noticed. This fluid 

 is secreted by the inner coat of the stomach, and is sup- 

 posed to act chemically on the alimentary substances, 

 since in many instances, the appearance produced is 

 precisely like that which remains after the action of a 

 chemical agent. 



The effect of the gastric liquor on different substan- 

 ces bears no proportion to their mechanical texture, or 

 other physical properties ; for while in some animals it 

 speedily dissolves bone, and the hardest membranes, it 

 produces not the slightest effect on other substances of 

 the most delicate texture, as the fibres of cotton, or 

 the skins of fruits. 



What is the chief agent of digestion! In what manner is it suppos- 

 ed that the gastric fluid operates on the aliment ? 



