374 



FOOD AND DIGESTION 



acid is also formed. The phenols, after absorption, are in part con- 

 jugated with glycuronic acid which is formed by the incomplete oxida- 

 tion of dextrose and are eliminated into the urine. Experiments have 

 been performed to determine whether or not the intestinal bacteria are 

 necessary to normal digestion. The weight of evidence is in favor of the 

 view that they are not. 



The Feces. The contents of the large intestine, as they proceed toward 

 the rectum, become more and more solid, lose more liquid and nutrient 

 parts, and gradually acquire the odor and consistency characteristic of 

 feces. After a sojourn of uncertain duration in the sigmoid flexure of the 

 colon, or in the rectum, they are finally expelled by the act of defecation. 

 The average quantity of solid matter evacuated by the human adult in twenty- 

 four hours is about 200 to 250 grams, but the amount and character vary 

 exceedingly according to the food eaten. Vegetable foods contain much 

 indigestible matter, while meats and meat diets leave very little unabsorbed 

 material to be expelled in the feces. 



TABLE OF COMPOSITION OF FECES. 



The amount of water varies considerably, from 68 to 82 per cent, and 

 upward. The following table gives about an average composition: 



Water ................................. ................ 733 .00 



Solids, comprising: 



a. Insoluble residues of the food, uncooked starch, cellulose, 



woody fibers, cartilage, horny matter, mucin, seldom 

 muscular fibers and other proteins, fat, and cholesterin . 



b. Certain substances resulting from decomposition of foods, 



indol, skatol, fatty and other acids; calcium and mag- 

 nesium soaps .................................... 



c. Special excretion, excretin, excretoleic acid (Marcet), 



and stercorin (Austin Flint) ....................... 



d. Salts chiefly phosphate of magnesium and phosphate p 267.00 



of calcium, with small quantities of iron, soda, lime, and 

 silica ............................................ 



e. Insoluble substances accidentally introduced with the 



food ............................................. 



f. Mucus, epithelium, altered coloring matter of bile, fatty 



acids, etc ........................................ 



g. Varying quantities of other constituents of bile and se- 



cretions .......................................... J 



1000 .00 



Intestinal Gases. Under ordinary circumstances, the alimentary 

 canal contains a considerable quantity of gases. The presence of gas in the 

 intestines is so constant and the amount in health so uniform that there can 

 be no doubt that its existence is a normal condition. 



