LABORATORY MANUAL OF PHYSIOLOGY. 



the solution with ammonium sulphate. How is the presence of 

 proteoses indicated ? How are they differentiated from peptones ? 



(e) Filter portion (d) and test the nitrate for the biuret reaction. 

 If present, what does it indicate ? 



(/) Take a portion of the fibrin which has been acted upon by 

 the acidulated glycerin extract, neutralize the mixture with sodium 

 carbonate, and place in a dialyzer over night. The next day test 

 the dialyzant for albumin, proteoses, and peptones. 



Test the fluid remaining in the dialyzer in the same way. Re- 

 sults ? Conclusions ? 



5. Place some fresh milk in a test-tube, in a water-bath at 38 C., 

 and add a few drops of rennet extract. What is the action of the 

 rennin ? Remove the fluid part of the milk so far as possible, and 

 add some artificial gastric juice. Is the casein dissolved ? 



VI. INTESTINAL DIGESTION. 



1. Emulsification. (a) Shake up 5 c.c. of olive oil in a test- 

 tube with an equal quantity of water. The mixture will become 

 milky white because of the distribution of oil globules through it. 

 Do these oil globules remain in suspension ? 



(b) Repeat the procedure in (a), adding to the mixture, before 

 shaking, 5 c.c. of strained egg albumin. Do the oil globules remain 

 in suspension ? Set this to one side and observe again, some hours 

 later. Has any of the oil begun to separate out ? 



(c) Repeat (6), substituting gum acacia for the egg albumin. 

 Set aside and observe later for the separation of oil from the 

 emulsion. 



2. Saponification. To 5 c.c. of olive oil or cottonseed oil add 

 twice the volume of a 20-per-cent solution of NaOH or KOH. 

 Shake well. Continue to agitate the mixture at frequent intervals 

 for fifteen to twenty minutes. Now add an excess of water. Has 

 the oil been dissolved ? What chemical reaction has taken place 

 between the oil and the alkali ? 



3. Saponification as an Aid in Emulsification. (a) Mix 

 a small quantity of oil which has become slightly rancid, with a 



