CLEAVAGE PRODUCTS OF GASTRIC DIGESTION 



to the following table. Add a definite quantity of fibrin to each and note 

 the changes at intervals of 20 minutes. 



B 



5 c.c. gas- 5 c.c. neutral 5 c.c. alka- 5 c.c. boiled 5 c.c. gastric 

 Prepare. . . . trie juice at gastric juice line gastric gastric juice | juice at o C. 

 40 C. at 40 C. juice at 4oC. at 40 C. 



Note after 

 20 min- 

 utes. 



After 40 

 minutes. 



After 60 

 minutes. 



14. Cleavage Products of Gastric Digestion. Add 5 to 10 grams 

 of fibrin to 500 c.c. of artificial gastric juice in a flask and place in a water- 

 bath at 40 C. After one hour filter off 100 c.c. Exactly neutralize this 

 filtrate with i per cent, potassium hydrate. A precipitate makes its appear- 

 ance, and can be collected on the filter-paper, washed with distilled water, 

 and dissolved in i per cent, dilute hydrochloric acid, acid albumin. Test for 

 the protein reactions. 



After twelve hours or more filter the remaining 400 c.c., exactly neutralize 

 to remove any traces of acid albumin, and filter. The filtrate contains pro- 

 teoses and peptones. Concentrate the filtrate over a water-bath to one- 

 fourth its volume, add an equal quantity of saturated ammonium sulphate 

 solution, a sticky precipitate of primary proteases separates out. Collect on 

 a filter-paper, wash with half- saturated ammonium sulphate, redissolve in 

 very dilute salt solution, and test for protein reactions. The primary pro- 

 teoses are precipitated by nitric acid. 



To the filtrate from the half-saturated ammonium sulphate add crystals 

 of ammonium sulphate until complete saturation with the salt. Dentero- 

 albumoses separate out. Collect on a filter-paper, wash, dissolve, and test 

 for proteins. The secondary proteoses are not precipitated by nitric acid. 



Finally the filtrate contains peptone. It can be isolated and tested by 

 concentrating over the water-bath, adding barium hydrate to slight excess 

 to remove the sulphate, filtering, and precipitating the excess of barium by 



