FUNCTIONS OF THE INTESTINAL JUICE. 181 



lated from the rest without injuring the mesentery or its blood- 

 vessels. One of the extremities of the isolated portion was closed, 

 and the other was retained by sutures at an opening in the ab- 

 dominal wall. The cut ends of the remainder of the intestine 

 were at the same time united, so that the continuity of the ali- 

 mentary 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 1011. 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 di- 

 gestive properties are very discordant, experiments giving opposite 

 results in different animals, and in the hands of different persons 

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

 testinal secretions it may be seen that the changes which the va- 

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



