PANCREATIC DIGESTION 197 



(b) 0.5 c.c. olive oil + 9.5 c c. water. 



(c) 0.5 c.c. olive oil + 8.5 c.c. water + i c.c. bile. 



(d) 5 c.c. neutral pancreatic extract -f- 0.5 c.c. olive oil + 3.5 c.c. water + 



i c.c. bile. 



(e) 5 c.c. neutral pancreatic extract + 3.5 c.c. water + i c.c. bile. 



Shake the tubes thoroughly, add a drop of toluene to each and place them 

 in an incubator or water-bath at 40 for 24 hours. At the end of this period 

 add a drop of phenolphthalein to each tube and titrate with N/2O NaOH to a 

 permanent pink color. Shake the tube during the titration. Record the 

 amount of N/2O alkali necessary to neutralize the contents of each tube. Which 

 tube required the most? Why? 



2. "Litmus-milk" Test. Into each of two test-tubes introduce 10 c.c. of milk 

 and a small amount of litmus solution. 1 To the contents of one tube add 3 c.c. 

 of neutral pancreatic extract 2 and to the contents of the other tube add 3 c.c. of 

 water or of boiled neutral pancreatic extract. Keep the tubes at 4OC. and note 

 any changes which may occur. What is the result and how do you explain it? 



3. Copper Soap Test for Lipase. Prepare a 2 :ioo agar-agar solution, mix 

 with an equal volume of 5 :ioo starch paste, incorporate in this mass about 

 1/40 of its volume of the neutral fat desired (butter, lard, etc.), heat with constant 

 agitation until a homogeneous emulsion is produced, pour into a Petri dish, and 

 cool rapidly. Distribute on the surface of the solidified mass with a fine pipet 

 small drops of the liquid to be tested, keep i hour at 38, pour a saturated aqueous 

 CuSO 4 solution over the surface, allow to stand 10 minutes, and rinse with 

 H 2 O. The presence of lipase is shown by the appearance of beautiful bluish- 

 green spots. These are copper soap. The addition of the starch, which is not 

 indispensable, produces a rather white opaque background against which the 

 spots appear very distinct. (Carnot and Mauban Compt. rend. Soc. Biol. 

 81, 98, 1918, Chemical Abstracts, 13, 457, 1919). 



4. Ethyl Butyrate Test. Into each of two test-tubes introduce 4 c.c. of water, 

 2 c.c. of ethyl butyrate, C3H 7 COO.C 2 H 5 , and a small amount of litmus powder. 

 To the contents of one tube add 4 c.c. of neutral pancreatic extract and to the 

 contents of the other tube add 4 c.c. of water or of boiled neutral pancreatic ex- 

 tract. Keep the tubes at 4OC. and observe any change which may occur. 

 What is the result and how do you explain it? Write the equation for the reac- 

 tion which has taken place. 



EXPERIMENTS ON PANCREATIC RENNIN 



Prepare four test-tubes as follows : 



(a) 5 c.c. of milk -f 10 drops of neutral pancreatic extract. 



(b) 5 c.c. of milk + 20 drops of neutral pancreatic extract. 



(c) 5 c.c. of milk + 10 drops of alkaline pancreatic extract. 



(d) 5 c.c. of milk -f- 20 drops of alkaline pancreatic -extract. 



Place the tubes at 6o-6sC. for a half hour without shaking. Note the 

 formation of a clot. 3 How does the action of pancreatic rennin compare with the 

 action of the gastric rennin? 



litmus-milk powder may be used if desired. To prepare it add i part of powdered 

 litmus to 50 parts of dried milk powder. For use in testing, i part of powdered litmus- 

 milk may be added to 9. parts of water (Hamilton: Jour. Bact., 6, 43, 1921). 



2 Commercial pancreatin may be used in this test if desired. 



3 This reaction will not always succeed, owing to conditions which are not well under- 

 stood. 



