144 



PHYSIOLOGICAL CHEMISTRY 



per cent hydrochloric acid and keep at 38-4OC. for at least 24 hours. Filter 

 off the residue, consisting of nuclein and other substances, and use the filtrate 

 as an artificial gastric juice. This filtrate contains pepsin, rennin, and the 

 products of the digestion of the stomach tissues, i.e., acid metaprotein (acid 

 albuminate), proteoses, peptones, etc. 



PREPARATION OF A GLYCEROL EXTRACT OF PIG'S STOMACH 



Take the one-fifth portion of the mucuos membrane of the pig's stomach not 

 used in the preparation of the artificial gastric juice, cut it up finely, place it 



Acidity IZO 



C.C.%,NaOH., lo . 



100 

 90- 

 60- 

 70- 

 60- 

 50- 

 40- 

 30- 

 20 

 10- 







Time 

 Interval 

 -minutes 



Acidity 

 100 



90- 

 60 

 70- 

 60- 

 50 

 40- 

 30- 

 ZO- 

 10- 



10 20 30 40 50 60 

 500c.c. coo/(io-izc) city water 

 at 1 P.M. 6 hrs. after lax meal 

 Subject J.T.L. 



FI<J. 41. CURVES SHOWING STIMULATORY 



POWER OF WATER. 



(Bergeim, Rehfuss and Hawk: Journal Bio- 

 logical Chemistry, 19, 345, 1914.) 



P 



Time 

 Interval 



Pepsin 



.-- ?~ e s .'H._ 



10 tO 30 40 50 60 



minutes 



400c.c. water SZhours after an 

 Ewa/d meal- Subject O.B. 



FIG. 42. CURVES SHOWING STIMULAT- 

 ORY POWER OF WATER. 

 (Bergeim, Rehfuss and Hawk: Journal 

 Biological Chemistry, 19, 345, 1914.) 



in a small-sized beaker and cover the membrane with glycerol. Stir frequently 

 and allow to stand at room temperature for at least 24 hours. The glycerol will 

 extract the pepsinogen. Separate, with a pipette or by other means, the glycerol 

 from the pieces of mucous membrane and use the glycerol extract as required in 

 the later experiments. 



PRODUCTS or GASTRIC DIGESTION 



Into the artificial gastric juice, prepared as above described, place the protein 

 material (fibrin, coagulated egg-white, or lean beef) provided for you by the 

 instructor, add 0.4 per cent hydrochloric acid as suggested by the instructor and 

 keep the digestion mixture at 4OC. for two to three days. Stir frequently and 

 keep free hydrochloric acid present in the solution (for tests for free hydro- 

 chloric acid see page 156). 



