1/4 PHYSIOLOGICAL CHEMISTRY. 



stools from a milk diet. Thus the stool of the infant is ordi- 

 narily nearly odorless and any decided odor may generally be read- 

 ily traced to some pathological source. 



A neutral reaction ordinarily predominates in normal stools al- 

 though slightly alkaline or even acid stools are met with. The 

 acid reaction is encountered much less frequently 

 FlG - 48 - than the alkaline and then commonly only fol- 



lowing a vegetable diet. 



The form and consistency of the stool is de- 

 pendent, in large measure, upon the nature of 

 the diet and particularly upon the quantity of 

 water ingested. Under normal conditions the 

 consistency may vary from a thin, pasty dis- 



CHARCOT-LEYDEN *-..'> 1 1 0,11-1 



CRYSTALS. charge to a firmly formed stool. Stools which 



are exceedingly thin and watery ordinarily have a 

 pathological significance. In general the feces of the carnivorous 

 animals is of a firmer consistency than that of the herbivora. 



It is frequently desirable for clinical or experimental purposes 

 to make an examination of the fecal output which constitutes the 

 residual mass from a certain definite diet. Under such conditions, 

 it is customary to cause the person under observation to ingest 

 some substance, at the beginning and end of the period in ques- 

 tion, which shall sufficiently differ in color and consistency from the 

 surrounding feces as to render comparatively easy the differentiation 

 of the feces of that period from the feces of the immediately pre- 

 ceding and succeeding periods. One of the most satisfactory meth- 

 ods of making this " separation " is by means of the ingestion 

 of a gelatin capsule containing about 0.2 gram of powdered char- 

 coal at the beginning and end of the period under observation. 

 This procedure causes the appearance of tuw black zones of char- 

 coal in the fecal mass and thus renders comparatively simple, the 

 differentiation of the feces of the intermediate period. Some 

 similar method for the " separation of feces " is universally prac- 

 ticed in connection with the scientifically accurate type of nutri- 

 tion or metabolism experiment which embraces the collection of 

 useful data regarding the income and outgo of nitrogen, and other 

 elements. 



Among the macroscopical constituents of the feces may be men- 

 tioned the following : Intestinal parasites, undigested food particles, 

 gall stones, pathological products of the intestinal wall, enteroliths, 

 intestinal sand and objects which have been accidentally swallowed. 



