DIGESTION OF NITROGENOUS SUBSTANCES. 41 



(2) Are all three ingredients of 



gastric juice necessary for 

 proteid digestion or not? 



(3) To what, therefore, may some 



cases of indigestion be due? 

 b. Compare tests 4 and 5. 



(1) In which tube is digestion more 



complete ? 



(2) What do you learn in regard 



to the effect of thorough 

 mastication of food? 



(3) What provisions within the 



stomach, however, might 

 accomplish the digestion 

 of even poorly masticated 

 food? 



B. Action of pancreatic juice. 

 i. Experiments. 



a. Into a test-tube put some of the 



minced egg; half fill the tube with 

 water and add pancreatin; add to 

 the mixture a little baking-soda or 

 other alkali. Label Test No. 6, 

 minced egg + water + pancreatin + 

 alkali. 



b. In a seventh tube mix the same quan- 



tity of minced egg, water, and pan- 

 creatin as was used in Test No. 6 ; 

 pour in a few drops of hydrochloric 

 acid. Label Test No. 7, minced 

 egg + water + pancreatin + acid. 

 . Put both tubes in a warm place (98 F.) 



