INTESTINAL JUICE. 265 



Intestinal Juice. 



Of the three fluids with which the food is brought in contact in the intestinal canal, 

 namely, the bile, the pancreatic juice, and the intestinal juice, the last, the secretion of 

 the mucous membrane of the small intestine, presents the greatest difficulties in the in- 

 vestigation of its properties and function. If it be admissible to reason from the known 

 mechanism of secretion in other parts, it is fair to suppose that the normal secretion 

 from the mucous membrane of the small intestine can only take place in obedience to 

 the stimulus of food. The same cause induces the secretion of the pancreatic juice and 

 increases the flow of bile. As we have already seen, the food, as it passes from the 

 stomach into the duodenum, is to a great extent disintegrated and is mingled with the 

 secretions from both the mouth and the stomach. Under these circumstances, it is evi- 

 dently impossible to collect the intestinal juice under perfectly physiological conditions, 

 in a state of purity sufficient to allow of extended experiments regarding its composition, 

 properties, and action in digestion. 



Bidder and Schmidt experimented upon dogs and cats, shutting off from the intestine 

 the bile and pancreatic juice, and found that starch introduced into the canal became 

 transformed into sugar. They also observed that fat was emulsified to a considerable 

 degree, and that albumen and meat were partially disintegrated and digested. These 

 observers were unable to collect the intestinal juice in quantity sufficient for analysis. 

 That which they obtained was found to be colorless, very viscid, and strongly alkaline 

 in its reaction. 



As far as the composition and general properties of the intestinal juice are concerned, 

 the observations of Colin upon horses are the most definite, although it is questionable 

 whether he succeeded in obtaining the fluid in a normal state. To collect the fluid, an 

 incision was made into the abdominal cavity, and from four and a half to six feet of the 

 small intestine were drawn out. 

 This portion was emptied by gen- 

 tly pressing with the finger from 

 above downward, while, with the 



other hand, the upper portion was <,---, x *- 



kept closed. Without removing gaJ> XE=J^= -^ * <~3 



the fingers, two soft clamps were r 



. r FIG. 71. Clamp for isolating a portion of the ^ntest^ne. (Colin.) 



then applied, thus shutting off the ^ i owe r plate; *, upper plate; C, fixed screw; D, movable screw in 



exposed part of the intestine from P lace ' ^ screw turned so as to allow the clamp to be passed 



1 around the intestine. 



the rest of the canal. The gut was 



then returned and the wound in the abdomen closed. At the end of half an hour, the 

 animal was killed by bleeding, and the contents of the isolated portion of the intestine 

 were examined. The quantity of juice obtained was considerable, being from 1,235 to 

 1,852 grains for about six and a half feet of intestine. It was always found to be much 

 less when intestinal digestion had been suspended, and its quantity could be increased by 

 the injection into the loop of a little solution of manna, sulphate of soda, or aloes. The 

 fluid thus obtained was clear, slightly yellowish, with a saline taste and an alkaline re- 

 action. It was mixed with mucus, which formed a sediment when the fluid was allowed 

 to stand, and could be separated by filtration. Notwithstanding the care with which 

 these observations were conducted, it is not probable that the fluid thus obtained by 

 Colin was the normal intestinal juice ; and it certainly does not correspond in its gen- 

 eral characters with the fluids which have been studied by other experimenters. 



It becomes an interesting question, in this connection, to determine whether the soli- 

 tary and the agminated glands produce any secretion which is discharged into the intes- 

 tinal cavity. Although these follicles are closed, the observations of Colin have shown 

 pretty conclusively that they are capable of producing a secretion ; but the precise mode 

 of its formation is not so apparent. The experiment by which this was demonstrated 



