192 GASTRIC DIGESTION : CHYMIFICATION. 



Chemists, render it probable that this change is of the nature 

 of fermentation. 



210. It is a fact of great practical importance, that a cer- 

 tain quantity of the gastric fluid can act only upon a limited 

 amount of alimentary matter ; so that, if more food be taken 

 into the stomach than the gastric fluid can dissolve, it remains 

 there undigested. Now it has been already mentioned, that 

 the quantity of the gastric fluid secreted at any one time, is 

 proportional, not to the amount of food in the stomach, but 

 to the wants of the system ; so that, if more food be swal- 

 lowed than is required to repair the waste of the body, it 

 lies for some time unchanged in the stomach, and becomes a 

 source of irritation which prevents the due discharge of its 

 functions ; and the evil goes on increasing with every addi- 

 tion to the contents of the cavity. This may not be felt by 

 the individual at the time ; but it leaves permanent effects, 

 which manifest themselves sooner or later in derangement of 

 the general health. The, habit of taking more food than is 

 really necessary, and of irritating the stomach by stimulating 

 substances or fluids (such as pepper, mustard, spirits, &c.), is 

 a fertile source of disease. The injurious effects of these are 

 manifested by the thirst which is the consequence of their 

 use, and which is a call (as it were) on the part of the stomach, 

 to prevent their irritating action by diluting them with water. 



211. By the solution of its albuminous portion, and the 

 separation of its other component particles, the food is re- 

 duced in the stomach to a kind of pulp, which is termed 

 chyme. The consistence of this will of course vary accord- 

 ing to the nature of the food, and the quantity of fluid in the 

 stomach ; but in general it is grayish, semi-fluid, and uniform 

 throughout. When the food has been of a rich character, the 

 aspect of the chyme resembles that of cream ; but when the 

 food has consisted of farinaceous substances (rice, potatoes, 

 &c.), the chyme is more like gruel. At the point where the 

 stomach opens into the intestinal canal, which is called the 

 pylorus, there is a kind of valve, which permits the chyme 

 to pass as fast as it is formed, but closes against the portions 

 of the food which are yet solid and undigested ; and thus the 

 chyme escapes from the stomach in successive waves, slowly 

 at first, but afterwards more rapidly, as the digestive process 

 approaches its completion. 



