244 PHYSIOLOGY OF ALIMENTATION. 



and salts with but very little or no enter okinase. 1 When the 

 secretion is poured out upon food the intestinal juice is rich 

 in enterokinase. Apparently much more powerful than the 

 food itself in bringing about an intestinal secretion are the 

 pancreatic ferments which, under ordinary circumstances, 

 accompany the food along the intestine. An isolated loop 

 which is secreting little or no juice will become active very 

 soon after a few cubic centimeters of pancreatic juice are 

 put into it. If the pancreatic juice is previously boiled, this 

 property is lost. Which of the pancreatic ferments is active 

 in this direction is not yet known. 



Observers agree that the normal enteric juice is a thin, 

 slightly yellowish liquid, ordinarily said to be alkaline in 

 reaction. The fluid which collects in the course of a few 

 weeks in loops of intestine which are ligatured off from the 

 main tube probably does not represent a normal secretion. 

 Usually this is more or less gelatinous and represents no 

 doubt the inspissated intestinal juice plus the mucin and 

 other abnormal substances poured out by the loop in conse- 

 quence of the "catarrh" which arises in it. 



The nervous system no doubt influences the secretion 

 from the small intestine, but in just what way is not known. 

 The statements made by different observers contradict each 

 other in many points. A secretion of fluid occurs into the 

 intestine when all the nerves passing to the loop have been 

 severed. This so-called " paralytic secretion" contains, ac- 

 cording to MENDEL'S observations, all the ferments present in 

 the normal juice. A secretion of fluid into isolated loops of 

 intestine when entirely removed from the body also occurs. 

 All the structures necessary for secretion must therefore be 

 contained in the wall of the gut, and it would no doubt be 

 straining a point should we attribute this secretion to the 

 nervous plexuses found in the wall of the intestine, and not 

 solely to the mucous membrane. The fluid secreted into 

 loops entirely removed "from the body is not to be regarded 



1 See p. 240, 



