REACTION OF INTESTINAL CONTENTS W 



and feces as do the lining of the urinary tract and large intestine. 

 When urine is injected under the skin, or, through rupture 

 of the intestine, fecal matter makes its way into the abdominal 

 cavity, they come into contact with tissues which, though 

 alive, are not adapted to resist them, and so lead to serious 

 consequences. Very suggestive results have been obtained 

 with extracts from intestinal worms which spend their entire 

 lives in the digestive secretions. Such extracts contain sub- 

 stances, precipitable by alcohol, which inhibit the action of 

 either pepsin or trypsin as the case may be. Fibrin may be 

 impregnated with the precipitated " antienzyme," which then 

 becomes resistant to the digestive action of the alimentary 

 secretions. These experiments are very suggestive, even 

 though it has not been possible to obtain similar bodies from 

 the intestinal mucous membrane. The antitrypsin which is 

 present in the blood has the same properties as the anti- 

 trypsin of intestinal worms. Finally, there has been found 

 in the blood of some animals an antikinase, which inhibits 

 not the action of trypsin but of enterokinase. 



Reaction of Intestinal Contents. The many confusing re- 

 sults obtained by different observers in testing the reactions 

 of intestinal contents are due partly to the indicators used. 

 Methyl orange, which is the most stable of the indicators usually 

 employed, is not affected by^weak organic acids, but reacts 

 acid to inorganic and the stronger organic acids, like lactic, 

 acetic, and butyric acid, and alkaline to the salts of the weaker 

 acids, such as sodium carbonate and bicarbonate. Phenol- 

 phthalein is very sensitive to acids, even to weak organic acids 

 like fatty acids and to carbonic acid. Litmus lies intermediate 

 in sensitiveness as an indicator. 



The chyme which comes through the pylorus is acid and 

 mingles in the duodenum with the alkaline bile and pancreatic 

 secretion. In time, therefore, the acid reaction in the duo- 

 denum, as tested with litmus, becomes less or even weakly 

 alkaline. But it soon becomes acid again, and the acidity 

 increases again for a while as the food passes along the intestine. 

 In the region of the ileocecal valve the contents may be neutral 

 or actually alkaline. To phenolphthalein the reaction is acid 

 throughout the small intestine, while methyl orange shows 

 an alkaline reaction except at times in the duodenum. When 



