CHAPTER VIII 



THE INTESTINAL HORMONE 



We have already referred (page 4) to the work 

 of the English physiologists, Bayliss and Starling, 

 on secretin. This work is of such a fundamental 

 character, that it well deserves a chapter all to 

 itself. 



In the preceding chapter we have shown how 

 the glycogenic function is controlled by a hormone 

 developed by the pancreas. We shall now proceed 

 to show that the pancreatic juice in turn is con- 

 trolled by a hormone which has its origin in the 

 lining of the upper part of the small intestine. 



Digestion in the small intestine. Even at the 

 risk of repeating what was said in the introduction, 

 let us state what happens in the small intestine 

 during digestion. You will remember that when 

 the valve connecting the stomach and intestine is 

 opened, the food passes from the former into the 

 latter. Here the food is acted upon by three liq- 

 uids, each containing either enzymes or other sub- 

 stances that help to simplify the food to the point 

 where it can be absorbed by the blood and lymph 



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