36 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



10 parts glycerin and allow to stand for three days. After 

 this time filter and precipitate the filtrate with alcohol and 

 wash with alcohol. On now dissolving the precipitate in 

 water we obtain a solution which has powerful digestive ac- 

 tion. (Heidenhain.) 



3. A watery infusion of the gland may be made only after it 

 has been exposed to the air for 24 hours, adding 5 to 10 parts 

 water for each part by weight of the gland. Salkowski sug- 

 gests the digestion of the finely divided gland at 40 0. with 

 water containing 5 to 10 c.c. chloroform per litre. After a few 

 days we obtain by this means an active solution of trypsin 

 which keeps. 



Properties. Trypsin is very soluble in water, but insoluble 

 in alcohol and glycerin. Its watery solution is not decom- 

 posed by long digestion at 40 C., and when evaporated it 

 yields a translucent, non-crystalline, yellowish solid residue. 

 Trypsin may be digested for a long time at 40 C. with caus- 

 tic soda without decomposing. 



Diastatic Ferment of the Pancreas (Amylopsin). 



Preparation. 1. Finely divided pancreas, best after ex- 

 posure for 24 hours to the air, is dehydrated first by being 

 placed in strong alcohol and afterwards in absolute alcohol, 

 the action of which should be continued for some time. The 

 dry solid, separated from the alcohol, is then macerated in 

 glycerin. The glycerin solution is precipitated by the addi- 

 tion of alcohol, filtered, washed with alcohol, dried over sul- 

 phuric acid, and then dissolved in water, (v. Wittich.) 



2. Precipitate the aqueous infusion of a pancreas which 

 has been treated with Mg 2 C0 3 with collodion, which carries 

 the proteids and the proteolytic ferment down with it in a 

 gelatinous form. The filtrate is concentrated by evapora- 

 tion in vacuo, and treated with strong alcohol, which throws 

 down a flocculent precipitate. Filter, and digest in a mixture 



