PRINCIPLES OF OSMOSIS. 45 



5. Place in another test-tube a little minced 



white of egg ; add bile and set aside for a 

 day or two. Does the egg dissolve? 



6. State what kinds of food-stuffs are acted 



upon by bile, and what kinds of food- 

 stuffs are not acted upon. 

 F. The digestive -action of pancreatic juice. 



I-. Prepare some artificial pancreatic juice as 

 directed in J8 B, adding the sodium car- 

 bonate solution to make it alkaline. 



2. Shake up a little melted butter with some of 



this pancreatic juice. What kind of a 

 mixture is formed? Examine under the 

 compound microscope. 



3. What kinds of food-stuffs are digested by 



the action of pancreatic juice (compare 

 previous experiments), and what kind of 

 food-stuffs are not acted upon? 



23. PRINCIPLES OF OSMOSIS. (Dem.) 



Materials : Thistle-tube, beaker-glass, grape-sugar, starch, white 

 of egg, Fehling's solution, iodine, nitric acid, and ammonia. Procure 

 the intestines of a sheep;* clean and inflate them; tie at intervals, 

 and allow this animal membrane to dry. 



A. Hold a thistle -tube upright, closing the smaller 

 end with the thumb. Into the larger end pour 

 a thick solution of grape-sugar (honey will 

 answer) until the liquid has half filled the tube 

 and nearly filled the bulb. Slit open one of 



* See foot-note p. 46. 



