APPENDIX 491 



to make one liter. In 100 cc. of this acidulated water put 100 

 milligrammes of a 6000 pepsin, or 150 mg. of a 4000, or 300 

 of a 2000 pepsin. Any commercial pepsin maybe used. Pre- 

 pare the proteid by boiling an egg, and then cutting the white 

 into small cubes or shreds. In place of the boiled egg some 

 of Merck's prepared fibrin may be used. 



With litmus paper test the reaction of the artificial gastric 

 juice. It will turn blue litmus paper red, thus showing that its 

 reaction is acid. 



Fill a test tube about one fourth full of the artificial gastric 

 juice, and add a few pieces of coagulated white of egg or of 

 fibrin ; then set the tube in a warm place, as in a water bath 

 regulated to about 37 C., or near a stove. Examine the tube 

 from time to time. The cubes of egg will be seen to be disinte- 

 grating and dissolving. 



A quantity of digested white of egg may be prepared in a 

 cup or bowl and emptied into the inner jar of a dialyzer. After 

 a time the water in the outer jar will give the peptone tests, 

 showing that the digested albumen is diffusible. 



PANCREATIC DIGESTION 



Procure some of the commercial pancreatic preparations and 

 make an artificial pancreatic juice according to the directions 

 furnished with each preparation. Test the reaction with litmus 

 paper. It will be found to be alkaline. Try the effect of the 

 artificial preparation on starchy and on albuminous substances 

 in the manner given above for each. The pancreatic juice will 

 be, found to change starch to grape sugar and proteids to pep- 

 tones. Try its effect also on oil by adding a few drops of olive 

 oil to some pancreatic juice in a test tube. At first the oil will 

 float on the surface of the liquid. Shake the tube vigorously 

 to mix the two substances. The oil will be broken up into fine 

 droplets, giving the contents of the tube a milky appearance. 

 On standing for a time it will be seen that the oil does not 

 separate from the digestive juice and collect at the surface as 

 it would if shaken up with water, but the two fluids remain 

 intimately mixed, forming an emulsion. Under a microscope 



