of the Stomach. 221 



the mental powers are capable of being exerted to the 

 highest advantage. There are persons constitutionally 

 dull, stupid and phlegmatic, who possess great vigour of 

 body, and a rapid digestion. To these, the above observ- 

 ations are not strictly applicable. So, important an in- 

 fluence has a sound digestion upon the whole state of the 

 body and mind, that many Physiologists have very prop- 

 erly styled the stomach the laboratory of the system. 



The immediate cause or instrument of digestion is the 

 bame in all those animals with whose structure and econ- 

 om^y we are thoroughly acquainted, though the steps pre- 

 paratory to this process are in many instances exceeding- 

 ly different. Thus in the Gallinaceous Class of Birds 

 the latter process is the result solely of maceration and 

 muscular action ; while in man and many other animals it 

 is performed by the action of the teeth, aided by the ope- 

 ration of the saliva. But^he digestive process so far as 

 it takes place in the stomach, is accomplished chiefly by 

 the gastric liquor. Some aid is, however, rendered by the 

 muscular action, and heat of the stomach ; and the process 

 is completed in the duodenum, by means of the solvent 

 and saponaceous powers of the pancreatic liquor, and bile. /^ 



The Gastric Liquor possesses some very singular and 

 very important properties. Its solvent or corrosive pow- 

 er is totally unlike that of any other fluid, with which we 

 are acquainted. It not only dissolves every species of 

 food suited to the sustenance of man, but also the stone 

 in the bladder, and some other substances of an equal or 

 greater density ; while it produces no corrosive effect up- 

 on several kinds of worms, which not only often live, but 

 grow rapidlj^, in the stomachs of men, and many other an- 

 imals. Neither does it produce any corrosive effect up- 

 the stomach which secreted it, while the living principle 

 remains ; but, when the living principle has become ex- 

 tinct, especially if the person was previously in health, its 

 corrosive effects are in some instances so powerful, as to 

 eat through all the coats in a few hours. It possesses, al- 

 so, powers eminently antiseptic, or opposed to putrefac- 

 tion. Were it destitute of this property, the food taken 

 into the stomachs of the sick and debilitated would, in 

 many instances, become putrid, and destroy life. The 

 same degree of heat, which is e^cr found in the stomach 



