DIGESTION AND THE DIGESTIVE AGENTS. 347 



but its validity is questioned. Just how it aids in the ab- 

 sorption of fats can not be told. The fact, however, remains 

 that in an animal in which none of the bile is allowed to 

 reach the intestine, which may be done easily by making 

 a biliary fistula, the fat is not so readily absorbed from the 

 intestine but accumulates there, and it may in large quan- 

 tities be actually lost from the body. By turning the stream 

 of bile back into the intestine and renewing the feeding of 

 fats, at once larger quantities of the fats are absorbed and 

 practically none are passed out. 



We know that the absorption of fat is not a physical 

 process, like the dialysis of sugar through the membrane, 

 but is a physiological process in which the epithelial cells 

 of the intestines actively pick up the fat, and it is probable 

 that the helpful action of the bile in the absorption of fats 

 is due to the direct stimulus which it exerts upon the epi- 

 thelial cells. A stimulus possibly not unlike the one which 

 it exerts upon the muscles of the intestine in arousing them 

 to greater peristaltic activity. 



Fifth. Bile is to a slight extent antiseptic, that is, it 

 destroys, or more properly, retards putrefying changes. 

 Such an antiseptic function has been assigned to it in the 

 intestine. But before calling attention to this antiseptic in- 

 fluence it will be desirable to explain more in detail the 

 reasons for the putrefying changes which occur here. Putre- 

 faction is a process of disintegration, a kind of fermenta- 

 tion caused by bacteria. Such bacteria, however, are not 

 dangerous ones; many are not only harmless, but actually 

 helpful. Such helpful bacteria live in untold numbers 

 normally and regularly in the human intestine. Here in 

 the nutritious contents of the intestine they induce putre- 

 factive changes, the important result of which is a soften- 

 ing and partial disintegration of the food. This softening 

 and partial disintegration no doubt aids materially in their 

 digestion, and without this disintegrating bacterial influence 

 the efficiency of the digestive changes would be very ma- 

 terially impaired. Digestion itself is a sort of disintegra- 



