232 PHYSIOLOGICAL CHEMISTRY 



While it is true that bacterial activity plays a considerable role in the 

 digestion of fats, a marked increase in fat usually indicates pancreatic 

 disease, or a disturbance in pancreatic function. This is, of course, the 

 case only when the amount of fat ingested is not in excess of that which 

 can be readily handled under normal conditions. In cases of pure 

 biliary obstruction without pancreatic involvement, fat-splitting takes 

 place in a normal way, but the fatty acids and soaps formed are not 

 absorbed owing to the absence of bile. Such a movement is full of 

 soaps and fatty acid crystals which on treatment with acetic acid show 

 a marked increase in total fat over normal. Failure of absorption 

 owing to extensive disease of the intestinal mucosa can produce a similar 

 picture but will usually give some cytological evidence of intestinal 

 disease. Pure pancreatic disease gives a marked increase in total and 

 neutral fat with the presence of bile. 



Undigested starches are readily recognized by their blue reaction with iodine. 

 This can be studied on the third slide. 



This phenomenon is the least frequent among the different forms of 

 pathological digestion and usually indicates food bolting, an excessive 

 ingestion of, or poor preparation of carbohydrate food, -or an infection 

 of the bowel with so-called "garungsdyspepsia" rather than an actual 

 disturbance of pancreatic function inasmuch as the amylolytic function 

 of the pancreas is the most persistent and the last to disappear. 



Disturbance in cellulose digestion, the presence of blood, leucocytes, 

 mucus, etc., can all be demonstrated by appropriate technic and represent 

 a chapter in the study of the feces of great diagnostic importance, but one 

 which is beyond the province of this volume. (For further discussion, 

 see page 228. For cuts of fecal constituents found microscopically, 

 see pages 230 and 231.) 



3. Reaction. Thoroughly mix the feces and apply moist red and blue litmus 

 papers to the surface. If the stool is hard it should be mixed with water before 

 the reaction is taken. Examine the stool as soon after defecation as is convenient, 

 since the reaction may change very rapidly. The reaction of the normal stools of 

 adult man is ordinarily neutral or faintly alkaline to litmus, but seldom acid. 

 Infants' stools are generally acid in reaction. Try the reaction to Congo red 

 paper. Also test the reaction of fecal extract to phenolphthalein. 



4. Starch. If any imperfectly cooked starch-containing food has been 

 ingested it will be possible to detect starch granules by a microscopical examina- 

 tion of the feces. If the granules are not detected by a microscopical examination, 

 the feces should be placed hi an evaporating dish or casserole and boiled with 

 water for a few minutes. Filter and test the filtrate by the iodine test in the usual 

 way (see page 45). 



5. Cholesterol, Koprosterol and Fat. Introduce about 5 grams of moist 

 feces into a 100 c.c. glass-stoppered cylinder. Add 30 c.c. of distilled water and 



