222 



PHYSIOLOGICAL CHEMISTRY 

 INFLUENCE OF DIET ON FECAL DRY MATTER 



The fecal pigment of the normal adult is hydrobilirubin This, 

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

 tine in the bile, the transformation from bilirubin to hydrobilirubin 

 being brought about through the activity of certain bacteria. Hydro- 

 bilirubin is sometimes called stercobilin 

 and bears a close resemblance to urobilin 

 or may even be identical with that pig- 

 ment. Neither bilirubin nor biliverdin 

 occurs normally in the fecal discharge of 

 adults, although the former may be de- 

 tected in the excrement of nursing in- 

 fants. If these pigments are found in 

 the feces of adults, they indicate an 

 abnormally rapid transit through the 

 large bowel thus preventing their trans- 

 formation into hydrobilirubin. Fre- 

 quently, in some way as yet unknown, 

 probably through the agency of certain bacterial processes, color- 

 less hydrobilirubinogen (leucohydrobilirubin) is formed which after 

 the passage of the movement and exposure to air is reconverted 

 into hydrobilirubin. This may explain in some cases the darken- 

 ing of the stool when exposed to the air. The most important 

 factor 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 brownish-black 

 stool, whereas the stool resulting from a milk diet is invariably light 

 colored. Certain pigmented foods, such as the chlorophyllic vegetables 

 and various varieties of berries, each afford stools having a characteristic 

 color. Certain drugs act in a similar way to color the fecal discharge. 

 This is well illustrated by the occurrence of green stools following the use 

 of calomel, of black stools after bismuth ingestion, and of yellow stools 

 following the administration of rhubarb, senna or santonin. The green 



FIG. 61. HEMATOIDIN CRYS- 

 TALS FROM ACHOLIC STOOLS. (v. 



Jaksch.) 



Color of crystals same as the color 

 of those in Fig. 56, page 205. 



