27 



and placed in 5-10 volumes of a saturated solution of salt. 

 The enzymes are dissolved and very active extracts are ob- 

 tained. The fat-splitting ferment is not active in this ex- 

 tract. This method is highly recommended by Harris and 

 Gow. (Jour, of Physiology, vol. XIII, 1892), but the solu- 

 tion putrefies after a time. 



115. Dilute alcoholic extract. Roberts recommends dilute 

 alcohol for obtaining an active solution of the pancreatic 

 enzymes. The fresh pancreas is freed from fat and chopped 

 up finely. Four times its weight of 25% alcohol is added 

 and the mixture is allowed to digest 4-5 days with occasional 

 agitation. It is then filtered through paper and is ready for 

 use. The alcohol assists in the preservation of the solution. 



116. There have been prepared for this exercise extracts 

 from the pancreas of the pig, ox and dog. Proceed in the 

 same manner with each extract and make notes of auj' dif- 

 ferences in their activity. Prepare three series of tubes ; 

 one series for the pig, another for the ox and another for 

 the dog. 



117. When ready to use, each test-tube is to be half filled 

 -with I % sodium carbonate and 30 drops of the pancreatic 

 extract added. To tubes prepared as above add the follow- 

 ing : I, a bit of fibrin ; 2, a small piece of dried albumin ; 3, 

 a piece of cooked meat; 4, a crumb of bread; 5, a bit of 

 ■cooked potato ; 6, a bit of cheese ; 7, a small amount of each 

 of the above .substances. Keep these in the water bath at 

 40° C. Note particularly any changes that may occur in 

 No. I , and compare with the fibrin digested with the gastric 

 juice. In those tubes which first show signs of digestive 

 action, test the contents for alkali-albumin by neutralization. 

 (Similar to the acid-albumin test the only difference being 

 the reaction of the digestive fluid). Te.st also for albumoses. 

 Place the tubes in the incubator until the next exercise and, 

 after filtering again te.st them for alkali-albumin, albumose, 

 and peptone, as with preceding tests. (104-107). Reserve 



