34 HUMAN PHYSIOLOGY 



subjected to the action of the secretions provided by 

 the glands of the small intestine (intestinal glands) 

 which appear to play some part or other in digestive 

 action, the exact duty of the secretion of the bowel 

 being as yet imperfectly understood. We are now 

 in a position to review the general conception of the 

 digestive system which, as has just been stated, is a 

 longer or shorter tube possessing an expanded por- 

 tion known as the stomach. Digestion is the journey 

 of food along this tube, and is accomplished through 

 the action of certain secretions or fluids contributed 

 by the digestive glands placed at the sides of the 

 tube, such secretions being poured upon the food at 

 different stages on its journey. 



THE DIGESTIVE JOURNEY. Simplifying thus our 

 view of the process of digestion we may divide the 

 digestive journey into three stages. The first of 

 these concerns what happens to the food in the 

 mouth, the second deals with digestion in the 

 stomach, and the third and last stage notes the 

 changes which the food undergoes in the intestine. 

 Following upon digestion itself we find another 

 function or duty, that of absorption. This latter 

 action is devoted to the conveyance from the 

 digestive system into the blood of digested food 

 which remains in the intestine, although, as we shall 

 note, a certain amount of the digested food leaves 

 the digestive system and passes into the blood at a 

 stage considerably earlier than that representing 

 the close of the digestive work. 



DIGESTION IN THE MOUTH. That digestion 

 really commences in the mouth is a fact not 

 generally appreciated. Many persons speak of 

 digestion as if that function was discharged by the 

 stomach alone. As a matter of fact, and curious 



