148 PHYSIOLOGICAL CHEMISTRY. 



starch paste. Be sure to introduce the starch paste into the tube last. 

 Why? Shake the tubes well and place them on the water-bath at 

 40 C. At the end of a half -hour divide the contents of each tube 

 into two parts and test one part by the iodine test and the other part 

 by Fehling's test. What are your conclusions ? 



4. Influence of Bile. Prepare five tubes as follows : 



(a) 2-3 c.c. of pancreatic extract + 2-3 c.c. of starch paste -f- 

 l / 2 -i c.c. of bile. 



(b) 2-3 c.c. of pancreatic extract +2-3 c.c. of starch paste + 

 1-2 c.c. of bile. 



(c) 2-3 c.c. of pancreatic extract + 2-3 c.c. of starch paste 

 + 2-3 c.c. of bile. 



(d) 2-3 c.c. of pancreatic extract + 2-3 c.c. of starch paste 

 + 5 c.c. of bile. 



(e) 2-3 c.c. of pancreatic extract + 2-3 c.c. of starch paste. 

 Shake the tubes thoroughly and place them on the water-bath 



at 40 C. Note the progress of digestion frequently and at the 

 end of a half hour divide the contents of each tube into two parts 

 and test one part by the iodine test and the other part by Feh- 

 ling's test. What are your conclusions regarding the influence 

 of bile upon the action of pancreatic amylase? 



5. Digestion of Dry Starch. To a little dry starch in a test- 

 tube add about 5 c.c. of pancreatic extract and place the tube on the 

 water-bath at 40 C. At the end of a half hour filter and test 

 separate portions of the filtrate by the iodine and Fehling tests. 

 What do you conclude regarding the action of pancreatic amylase 

 upon dry starch? Compare this result with that obtained in the 

 similar experiment under Salivary Digestion (page 58). 



6. Digestion of Inulin. To 5 c.c. of inulin solution in a test- 

 tube add 10 drops of pancreatic extract and place the tube on the 

 water-bath at 40 C. After one-half hour test the solution by 

 Fehling's test. 1 Is any reducing substance present? What do 

 you conclude regarding the digestion of inulin by pancreatic 

 amylase ? 



EXPERIMENTS ON PANCREATIC LIPASE. 



i. "Litmus-Milk" Test. Into each of two test-tubes intro- 

 duce 10 c.c. of milk and a small amount of litmus powder. To 

 the contents of one tube add 3 c.c. of neutral pancreatic extract 



1 If the inulin solution gives a reduction before being acted upon by the 

 pancreatic juice, it will be necessary to determine the extent of the original 

 reduction by means of a "check" test (see page 47). 



