ORGANS OF DIGESTION 113 



ole of holding about three pints, when moderately distend- 

 ed As already stated, under fig. 74, a, is the esophagus 



Fig. 79. 



or passage from the mouth ; b, 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. 



327. Gastric Juice. The chief agent concerned in di- 

 gestion is the gastric juice, as already noticed. This fluid 

 \s 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. 



328. The effect of the gastric liquor on different sub- 

 stances 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 supposed 

 that the gastric fluid operates on the aliment ? 



10* 



