ACTION OF THE INTESTINAL JUICE IN DIGESTION. 267 



end of the intestine, she soon improved in her nutrition and was then made the subject 

 of extended and interesting observations upon intestinal digestion. 



With regard to the general properties of the intestinal juice, the observations of Busch 

 upon his case of intestinal fistula agree with those of Bidder and Schmidt upon the lower 

 animals. He never, in the natural condition, found a large quantity of secretion in the in- 

 testine. The fluid was white or of a pale rose-color, consistent, and always strongly alka- 

 line. The maximum proportion of solid matter which it contained was 7*4 and the mini- 

 mum, 3-87 per cent. The secretion apparently could not be obtained in sufficient quantity 

 for ultimate analysis. No better opportunity than this could be presented for studying 

 the intestinal juice in its pure state. The nature of the case made it impossible that there 

 should be any admixture of food, pancreatic juice, bile, or the secretion of the duodenal 

 glands ; and, during the process of digestion, the lower part of the intestine undoubtedly 

 produced a fluid of perfectly normal character. When we come to consider the action 

 of the intestinal juice upon the various articles of food, our most reliable facts will be 

 drawn from the observations made upon this case. 



From what has been ascertained by experiments upon the lower animals and observa- 

 tions on the human subject, the intestinal juice has been shown to possess the following 

 characters : 



Its quantity in any portion of the mucous membrane which can be examined is small ; 

 but, when the extent of the canal is considered, it is evident that the entire quantity of 

 intestinal juice must be great, although, beyond this, no reliable estimate can be made. 



The intestinal juice is viscid and has a tendency to adhere to the mucous membrane. 

 It is generally either colorless or of a faint rose-tint, and its reaction is invariably alkaline. 



With regard to the composition of the intestinal juice, little of a definite character has 

 been learned. All that can be said is that its solid constituents exist in the proportion 

 of about 5 '47 parts per hundred. In most analyses of fluids from the intestine, there is 

 reason to believe that the normal intestinal juice was not obtained. 



The organs which secrete the fluid known as the intestinal juice are the follicles of 

 Lieberkuhn, the glands of Brunner, and possibly the solitary follicles and patches of Peyer. 

 The fluid, however, is chiefly secreted by the follicles of Lieberkuhn, which, as we have 

 seen, exist in the mucous membrane of the intestine in immense numbers. Although the 

 other organs mentioned do not contribute much to the secretion, they produce a certain 

 quantity of fluid; and the intestinal juice must be regarded as a compound fluid, like the 

 saliva, and not the product of a single variety of glands, like the gastric juice. 



Action of the Intestinal Juice in Digestion. 



The physiological action of the intestinal juice has been closely studied in the inferior 

 animals by Frerichs and by Bidder and Schmidt, but their experiments have been some- 

 what contradictory. All observers, however, are agreed that this fluid is more or less 

 active in transforming starch into sugar. We must turn finally to the observations of 

 Busch, on the case of intestinal fistula in the human subject, for the most satisfactory and 

 definite information on this subject. In many points, it is true, these observations sim- 

 ply confirm those which have been made upon the inferior animals, but they are of great 

 value, as they establish conclusively many important facts regarding the physiological 

 action of the intestinal juice in the human subject. 



In the case reported by Busch, starch, both raw and hydrated, when introduced into 

 the lower opening, where it came in contact only with the intestinal juice, was invariably 

 changed into glucose. Cane-sugar was not transformed into glucose but appeared in 

 the faeces as cane-sugar. This is important, with reference both to the want of action 

 of the intestinal juice upon cane-sugar and the fact that cane-sugar, as such, is not ab- 

 sorbed in quantity by the intestinal mucous membrane. 



Coagulated albumen and cooked meat were always more or less digested by the intes- 

 tinal juice. This fact coincides with the observations of Bidder and Schmidt. 



