GASTRIC DIGESTION. 53 



forty minutes A is turbid, and the fibrin is dissolved. In 

 B and no change. At the end of an hour, filter A and 

 part of B and C. Keep the filtrates. 



(c.) Carefully neutralise the filtrate of A with dilute 

 caustic soda. The filtrate becomes turbid and gives a pre- 

 cipitate of parapeptones (antialbumose and hemialbumose). 

 Filter off this precipitate, dissolve it in 0'2 per cent, hydro- 

 chloric acid. It gives proteid reactions. 



(d.) With a solution of parapeptones (hemialbumose) 

 repeat the ordinary reactions for proteids. Hemialbumose 

 is soluble in water, and gives all the ordinary proteid 

 reactions. It is precipitated by nitric acid in the cold, but 

 the precipitate is redissolved with the aid of heat. 



(e.) Test the filtrate of (c.) for peptones. Repeat all the 

 tests for peptones (Lesson I., 10, VI.) Note that hemial- 

 bumose gives the ordinary proteid reactions. Note also the 

 differences between peptones and hemialbumose. Hemi- 

 albumose is precipitated by acetic acid and ferrocyanide of 

 potassium ; by acetic acid and a saturated solution of sodic 

 sulphate ; and by metaphosphoric acid : which peptones are 

 not. Like peptones, it is soluble in water. 



(f.) Neutralise part of the filtrates of B and C. They 

 give no precipitate, nor. do they give the reactions for pep- 

 tones. In B the ferment pepsin was destroyed by boiling, 

 while in C the ferment cannot act in an alkaline medium. 



(g.) If to the remainder of C acid be added, and it be 

 placed again at 40 0., digestion takes place, so that neutralisa- 

 tion has not destroyed the activity of the ferment. 



5. To prepare Hemialbumose and Gastric Peptones in Quantity. 



(a.) Place 10 grms. of fresh, well-washed, expressed fibrin 

 in a porcelain capsule, cover it with 300 cc. of - 2 per 

 cent, hydrochloric acid, and keep the whole at 40 C. in a 

 water-bath until the whole of the fibrin is so swollen up as 

 to become converted into a perfectly clear, jelly-like mass, 

 and it becomes so thick that a glass rod is supported erect 

 in it. 



(b.) Add 1 or 2 cc. of glycerin pepsin extract, and stir 



