CHAPTEK XI. 



THE FECES. 



I HAVE shown in the preceding chapters that the greater portion 

 of the ingested food is transformed in the gastro-intestinal canal 

 into material which can be utilized by the body for purposes of 

 nutrition, and is there absorbed. A certain proportion, however, 

 invariably escapes digestion, and is partly decomposed by the 

 bacteria of the intestinal canal into the various substances which 

 have been considered in the preceding chapter. These substances 

 in turn are in part absorbed, and are partly eliminated in the feces, 

 together with particles of undigested food and undigestible material 

 which have passed through the digestive tract as such. In addition 

 we find here the various native and decomposition -products of the 

 bile, the pancreatic juice, the enteric juice, in so far as they have not 

 been absorbed, together with intestinal mucus, desquamated epithe- 

 lial cells, and bacteria. 



Consistence and Form. The consistence and form of the feces 

 are principally dependent upon the amount of water that is present, 

 and vary in different animals. Generally speaking, they are softer 

 in the herbivorous animals than in the carnivora. In man they 

 usually occur in the characteristic plastic, cylindrical form, but they 

 may at times be mushy, or round and hard, even in health. 



Amount. The amount of fecal material which is eliminated in 

 the twenty-four hours depends primarily upon the amount and the 

 character of the food that has been ingested. In man it normally 

 varies between 100 and 200 grammes, but may diminish to 60 

 grammes or rise to 250 grammes, even in health, according to the 

 preponderance of animal food or of vegetable material, which has 

 entered into the composition of the diet. 



Odor. The disagreeable odor of the feces is largely due to indol 

 and skatol, but may be further increased by the presence of hydro- 

 gen sulphide, methane, and methyl-mercaptan. 



Color. The color varies with the character of the food ingested, 

 and is usually but little influenced by the decomposition-products 

 of the biliary pigments. In carnivorous animals the feces are almost 

 black, owing to the presence of hsematin and sulphide of iron. In 

 adult man the color normally varies from a light to a dark brown. 

 In infants in which the bile-pigments appear as such the feces are 

 of a bright-yellow or a greenish-yellow color. 



At times and apparently under normal conditions stools are also 

 passed which are grayish white in color and closely resemble the 

 so-called acholic stools which are observed in cases of biliary ob- 



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