DIGESTION. 119 



and contributes to their solution by the soap which the alkalies of 

 the bile produce. The enmlsification of fat is a mechanical prepa- 

 ration of it, in order that lipase may act upon it. By thus rendering 

 the fats alkaline in part they are able to come in closer touch, with 

 the intestinal mucous membrane, and to be absorbed by it. Endos- 

 motic experiments have proved that the fats are imbibed and that 

 -they traverse more easily membranes that are impregnated with an 

 alkaline solution than those simply wet with water. Experimentally, 

 when the bile is turned out of its course, the chyliferous vessels are 

 not filled with white, milky fluid, since only one-seventh of the 

 normal amount of chyle is absorbed. 



When the chyme passes into the duodenum, the glycocholate 

 and taurocholate of sodium are broken up by the acid in the chyme 

 to form sodium chloride, at the same time setting the bile acids free. 

 Immediately they are precipitated, carrying down with them the 

 pepsin, making the chyme alkaline and more turbid, due to the 

 precipitation of the unpeptonized proteids. This thickening of the 

 stomach contents aids very materially in slowing the movements of 

 the digested products through the intestines, thus giving the villi 

 and blood-vessels more ample time to absorb nutritious substances. 



By rendering the chyme alkaline, it aids the action of the 

 pancreatic juice, which is most effective as a digestive agent in an 

 alkaline medium, at the same time favoring absorption, since alka- 

 line liquids permit of more ready osmosis. 



The bile itself easily becomes putrid on standing. How can it 

 prevent the putrescence, then, of the intestinal contents ? That it does 

 in some way diminish this degenerative process is very evident, for, 

 when the common biliary canal is ligated, the faeces are more foetid and 

 the intestinal gases more abundant. The bile's so-called antiseptic 

 powers must be accounted for by its hastening absorption and 

 assisting it to such an extent that the quantity of matter capable 

 of putrefaction is greatly diminished in quantity. Bile, as a rule, 

 increases peristaltic contraction of both the large and small intes- 

 tine. Taurocholic and glycocholic acid act in the same manner. 

 But bile also can at times retard the intestinal movements with or 

 without subsequent acceleration of the peristaltic act. 



. By this action the economy possesses a natural purgative. By 

 it, as a stimulus, the secretion of the glands of the intestinal 

 mucous membrane is increased, and more rapid peristaltic move- 

 ments of the intestinal muscles induced to aid in the propulsion 

 of their contents. 



