262 APPLIED PHYSIOLOGY 



(1) traction upon the nerves which run beneath the 

 parietal peritoneum (the visceral peritoneum is insen- 

 sitive), or (2) from violent contraction of the muscular 

 coat, producing local anaemia, which stimulates the 

 nerves of the bowel. 



Thus, the separation of adhesions which do not 

 involve the abdominal wall is painless, but if they 

 exist between the intestine and abdominal wall their 

 separation produces pain. The pain of colic or of 

 violent peristalsis is probably produced in the second 

 method by an overcontraction of the muscular coat, and 

 resembles the pain of ' cramp.' 



Absorption. 



Absorption of the soluble products of digestion is 

 carried out almost entirely in the small intestine ; that 

 of water in the colon. Observations on cases of fistula 

 at the lower end of the ileum have shown that by the 

 time the contents of the bowel have reached that point 

 87 per cent, of the nutriment of the food has already 

 entered the blood. It can readily be understood from 

 this that in cases of diarrhoea due entirely to disease of 

 the colon a patient's nutrition does not appreciably 

 suffer. Even when the passage of the food through the 

 small bowel is accelerated, as in enteritis, absorption 

 is not interfered with so much as one might expect, 

 owing, apparently, to the enormous provision made for 

 it by the great length of the ileum. It is only, indeed, 

 in cases of severe disease of the intestinal mucous 

 membrane, such as amyloid degeneration, or where the 

 lymphatics leading from the bowel are blocked, as in 



