264 Journal of Agriculture. [8 May, 1908^ 



3. diastase called also amylo-psin which transforms starch and dextrins- 



into the sugar maltose, 



4. erefsin which transforms proteoses into amino-acids, 



5. frotryfsin a proferment which has in itself no action, but which, 



by coming into contact with a constituent of the succus entericus- 

 called enter oMnase, is transformed into trypsin a remarkably 

 powerful ferment, wliich changes proteins into amino-acids. 



The bile is a fluid of a yellow or greenish tint and with a characteristic 

 taste. It contains, besides some 92 per cent, of water and in most cases. 

 a little protein, the following bodies : — 



1. hilc salts, which are compounds of sodium and potassium with 



complex organic acids {glycocholic and taurocJiolic acids). The- 

 importance of these salts is to be found in their power of dis- 

 solving fatty acids which would otherwise be insoluble. These- 

 salts being alkaline also help in neutralising the chyme. 



2. pigments — to be looked on as excreta and probably due to the 



broken-down red colouring-matter of the blood, 



3. lipoid — probably from the corpuscles of the blood and to be looked 



on as waste matter. 

 The succus entericus of the duodenum and small intestines is a more 

 dilute fluid containing besides mucin: — 



1. enter okinase, which transforms protrypsin into trypsin, 



2. erepsin, which transforms proteoses into amino-acids, 



3. maltase, which transforms maltose into glucose, 



4. lactase, which transforms lactose into glucose and galactose, 



5. invertase, which transforms cane sugar into glucose and levulose. 

 The chyme, neutralised and mixed with bile and pancreatic juice, is; 



urged along the small intestine by peristalis, receiving succus entericus on 

 its way and having a certain amount of digested material absorbed from it. 

 The course of digestion here may be summarized as follows: — The un- 

 digested and semi-digested proteins of the chyme are attacked by trvpsin 

 and disintegration into amino-acids commences. The proteoses present 

 undergo the same change through the presence of erepsin. Fat is split 

 by the lipase into glycerine and fatty acids which latter are dissolved bv 

 the bile. Starch and dextrins are broken down into sugar by the diastase 

 and compound sugars are split into simple sugars by the ferments of the 

 succus entericus. The sojourn of the chyme in the small intestine is not 

 nearly long enough for these changes to be completed ; the ferments are 

 added and the action begun but the completion of the process takes place 

 in the lower tracts of the bowel. 



Absorption in the small intestine can be shown to be undoubted] \ 

 present and affecting all classes of food but especially the fats and sugars. 

 The fatty acids dissolved in bile, together with the glycerine, are absorbed 

 by the lining cells and recombined into fat. The fat in the form of small 

 globules is carried bv white cells capable of movement into the central 

 lacteals of the villi and thus sent into the circulation bv the lymphatic 

 system. A small portion does not do so, however, being either absorbed 

 directly in the blood stream and sent on to the liver, or retained as fat 

 in the gut wall. The simple sugars, dextrose, levulose and galactose, and 

 the products of protein digestion are absorbed as soon as they are 

 formed and come in contact with the villi of the mucous membrane. The 

 path of their absorption is undoubtedly through the blood vessels passing: 

 thence to the portal vein and liver, but the fate of these digested products, 

 is rather shrouded in mvsterv. The little that is known mav be brieflv 



