188 MANUAL OF PHYSIOLOGY. 



was retained by sutures at an opening in the abdominal wall. 

 The cut ends of the remainder of the intestine were at the same 

 time united, so that the continuity of the alimentary tract was 

 preserved. Thus, a limited piece of gut formed a cul-de-sac from 

 which the fluid could be collected through a fistulous opening. 



Characters of the Secretion. The fluid obtained from 

 such a fistula is a thin, opalescent, yellowish fluid with a strong 

 alkaline reaction and a specific gravity of 101 1. It contains some 

 proteid and other organic material, a ferment and inorganic salts 

 in which sodium carbonate preponderates. 



Mode of Secretion. The secretion flows but slowly from 

 such a fistula, but the amount increases during digestion, showing 

 that the secretion of the intestine is under the control of some 

 nerve centre which can call the entire tract into action when one 

 part is stimulated. Moreover, the local stimulation of the mucous 

 membrane makes it red, and causes it to pour out a more abundant 

 secretion. Beyond this little is known of the nervous mechanism 

 or the local cell changes which accompany the formation of the 

 secretion. 



Functions of the Intestinal Juice. All the properties 

 of the secretion of the pancreas have been accorded to the intes- 

 tinal juice. It is said to have a ferment, capable of being ex- 

 tracted with glycerin, which can convert cane sugar and starch 

 into grape sugar, and bring about lactic fermentation. It dis- 

 solves fibrin very slowly and still less easily other proteids. It is 

 also said to emulsify fats. However, the observations as to its 

 digestive properties are very discordant, experiments giving oppo- 

 site results in different animals, and in the hands of different per- 

 sons even in the same animal. From the foregoing account of 

 the intestinal secretions, it may be seen that the changes which 

 the various kinds of food undergo on their way through this part 

 of the alimentary tract are numerous ; a short review may there- 

 fore be useful. 



When the acid gastric chyme flows into the duodenum, a flow 

 of bile takes place from the gall bladder, and at the same time 

 the secretions of the pancreas, Brunner's glands, and Lieberkuhn's 

 follicles are poured copiously into the intestine. The bile meeting 



