PROCESSES OF THE LARGE INTESTINE. 



337 



In addition, the color of the food has considerable effect. Thus the presence 

 of much blood in the food renders the feces almost brownish black, from hematin; 

 green vegetables render them brownish green, from chlorophyll; bones, in dogs, 

 render the feces white, from the calcium contained; bluish-red vegetable juices 

 render them bluish black; iron-preparations stain them black in part, from the 

 production of iron sulphid. 



The feces contain (Fig. 125): 



i. The secreted juice of the intestinal mucous membrane, together 

 with desquamated and digested epithelial cells. After almost complete 

 absorption of the digested food, the feces still contain from 8 to 9 per 

 cent, of nitrogen, from 12 to 18 per cent, of ethereal extract and from 

 ii to 15 per cent, of ash. Certain articles of food stimulate these excre- 

 tions more vigorously than others. 



If a loop of the lower portion of the small intestine and the upper portion of 

 the large intestine be excluded, as in a Thiry's fistula, and it be replaced in the 



FIG 125. Feces: a, muscle fibers; b, tendon; c, epithelial cells; d, leukocytes; e-i, various forms of plant-cells, 

 among which everywhere large numbers of bacteria (i) are scattered; between h and b are yeast-cells; *, 

 ammoniomagnesium phosphate. 



abdominal cavity after being closed by a circular suture, a mass of fecal char- 

 acter will be found in it. A loop of colon, thus excluded, will contain only a 

 watery transudate, rich in salts. 



2. The indigestible residue of the tissues of animal or vegetable food: 

 hairs, horny tissue, elastic tissue; most forms of cellulose, wood-fibers, 

 fruit-stones, spiral vessels from plant-cells, gum. 



3. Fragments of otherwise readily digestible substances, particularly 

 when they were ingested in excessive amount, or when not sufficiently 

 comminuted by mastication; thus, the remains of meat (up to i per 

 cent.), pieces of ham, shreds of tendon, bits of cartilage, flakes of fatty 

 tissue, small pieces of hard albumin; further, plant-cells, starch in 

 vegetable cells, firm-walled cells of ripe pulses, unground adhesive cell 

 of grain, and the like. The presence of meat and starch is suggestive 

 of an existing intestinal catarrh. 



Of all articles of food certain remnants pass over into the feces: of wheat- 

 bread, 3-7 Per cent.; of rice, 4-1 per cent.; of meat, 4.7 P^ cent.; of potc es, 

 9.4 per cent.; of cabbage, 14.9 per cent.; of rye-bread, 15 per cent.; of carrots, 

 20.7 per cent. 



