500 VICTOR C. MYERS ~T 



ture of mucus, pus, blood and pathological products of the intestinal wall 

 may cause the total amount of feces to he markedly increased. 



Consistency. The form and consistency of the feces is dependent, in 

 large measure, upon the nature of the diet. Under normal conditions the 

 consistency may vary from a thin, pasty composition to a firmly formed 

 stool. Feces which are exceedingly thin and watery generally have a path- 

 ological significance. 



Color. The fecal pigment of the normal adult is hydrobilirubin, also 

 called stercobilin. It has its origin in the bilirubin of the bile, being 

 formed by the reducing action of certain bacteria. Hydrobilirubin is 

 probably identical with the urobilin of the urine. This pigment is pres- 

 ent in both the urine and feces, partly in the form of its chromogen, 

 urobilinogen. This is transformed to urobilin under the action of light. 

 Normally hydrobilirubin appears to be largely reabsorbed and converted 

 to bilirubin. In pernicious anemia the destruction of red cells is so rapid 

 that it cannot be reabsorbed, thus leading to a marked excretion of the 

 reduced pigment in the stool, a very valuable point in the differential 

 diagnosis of primary and secondary anemia. (It is not. increased in sec- 

 ondary anemia.) In certain liver diseases there is sometimes a breakdown 

 in the ability to reconvert urobilin to bilirubin, which leads to the appear- 

 ance of the pigment in the urine in abnormal amounts. Neither bilirubin 

 nor biliverdin occur normally in the feces of adults, although bilirubin 

 sometimes occurs in the stools of nursing infants. 



The diet is the most important factor in determining the color of the 

 feces. On a mixed diet the stools may vary in color from light, to dark 

 brown, on an exclusive meat diet the stools are brownish black, while on 

 a milk diet they are invariably light colored. Cocoa produces reddish 

 brown feces, while with certain berries the feces may be almost black. 

 Pathologically, absence of bile, or any condition producing a large amount 

 cf fat, gives clay colored stools; blood from the upper part of the ali- 

 mentary tract yields "tar feces." 



Odor. The odor of normal feces is generally stated to be due to skatol 

 and indol. However, these aromatic putrefactive substances are generally 

 found in such small amounts as to be an insufficient explanation on this 

 point. Hydrogen sulphid and methylmercaptan probably play a certain 

 part in the disagreeable character of the odor. The intensity of the odor 

 depends to a large extent upon the diet, being very marked in stools from a 

 meat diet, much less marked in stools from a vegetable diet y and often 

 hardly detectable on stools from a milk diet. The stool of the infant is 

 ordinarily quite odorless, and any decided odor may generally be traced 

 to some pathological source. 



A simple division of fecal material may be based upon the separation 

 afforded by the customary procedures, viz., the estimation of the total 

 nitrogen, ethereal extract, carbohydrate residues and ash. The results 



