FECES. 



173 



FIG. 47. 



The fecal pigment of the normal adult is hydrobilirubin. This 

 pigment originates from the bilirubin which is secreted into the in- 

 testine in the bile, the transformation from bilirubin to hydrobili- 

 rubin being brought about through the activity of certain bacteria. 

 Hydrobilirubin is sometimes called stercobilin and bears a close re- 

 semblance to urobilin or may even be identical with that pigment. 

 Neither bilirubin nor biliverdin occurs normally in the fecal dis- 

 charge of adults, although the former may be detected in the ex- 

 crement of nursing infants. The most important factor, however, 

 in determining the color of the fecal discharge is the diet. A 

 mixed diet for instance produces 

 stools which vary in color from 

 light to dark brown, an exclusive 

 meat diet gives rise to a brown- 

 ish-black stool, whereas the stool 

 resulting from a milk diet is in- 

 variably light colored. Certain 

 pigmented foods such as the chlo- 

 rophyllic vegetables, and various 

 varieties of berries, each afford 

 stools having a characteristic 

 color. Certain drugs act in a 

 similar way to color the fecal dis- 

 charge. This is well illustrated by 

 the occurrence of green stools following the use of calomel and of 

 black stools after bismuth ingestion. The green color of the calo- 

 mel stool is generally believed to be due to biliverdin. v. Jaksch, 

 however, claims to have proven this view to be incorrect since he 

 was able to detect hydrobilirubin (or urobilin) but no biliverdin 

 in stools after the administration of calomel. The bismuth stool 

 derives its color from the black sulphide which is formed from 

 the subnitrate of bismuth. In cases of biliary obstruction the 

 grayish-white acholic stool is formed. 



Under normal conditions the odor of feces is due to skatole and 

 indole, two bodies formed in the course of putrefactive processes 

 occurring within the intestine (see page 162). Such bodies as 

 methane, methyl mercaptan and hydrogen sulphide may also add 

 to the disagreeable character of the odor. The intensity of the 

 odor depends to a large degree upon the character of the diet, being 

 very marked in stools from a meat diet, much less marked in 

 stools from a vegetable diet and frequently hardly detectable in 



CRYSTALS FROM ACHOLIC 

 STOOLS. (v. Jaksch.) 



Color of crystals same as the color of 

 those in Fig. 41, p. 153. 



