DIGESTION, CIRCULATION, AND ABSORPTION 273 



Method. In No. 1 place minced white of egg + water. In No. 2 

 minced white of egg +.2% HCL. In No. 3 minced white of egg -f .2% 

 HC1 + pepsin. Numbers 4 and 5 as No. 3. Place Nos. 1, 2, and 3 near 

 the register or radiator, or in a water bath, so as to keep them at about 

 blood heat for a few hours. Place No. 4 in a vessel surrounded with 

 cracked ice, or in as cool a place as possible for a few hours. Place 

 No. 5 in boiling water for 15 or 20 minutes, then set it aside with Nos. 1, 

 2, and 3. 



Observation. Test No. 1 with the biuret l test for presence of peptone. 

 Result? 



Conclusion. What is your conclusion as to the action of water on 

 proteid ? 



Observation. Test No. 2 as No. 1 was tested. What do you observe ? 



Conclusion. Does hydrochloric acid change proteid into a soluble 

 state ? 



Observation. Test No. 3 as you tested Nos. 1 and 2. What do you 

 observe ? 



Conclusions. 1. What is your conclusion as to the effect of HC1 + 

 pepsin on proteid ? 



2. Is the resulting substance soluble or insoluble ? 



Note. If the proteid has been made soluble by the action of pepsin, 

 it is because it has been made into a soluble substance known as peptone. 



Observation. Test Nos. 4 and 5 as Nos. 1, 2, and 3 were tested. What 

 do you observe ? 



Conclusions. 1. What are your conclusions as to the effects of high 

 temperature and of low temperature on the action of pepsin on a proteid ? 

 Explain. 



2. Write a connected account of all your conclusions here. Try 

 tabulating your results. 



c. In the Small Intestine 



1. ACTION OF PANCREATIC JUICE (OPTIONAL) 



Materials. Pancreatin, sodium carbonate or baking soda, starch, pro- 

 teid, olive oil or butter, water bath. 



Note. Artificial pancreatic juice may be made by mixing 10 grains of 

 pancreatin with 20 grains of baking soda and adding 200 cc. of water. 



Method a. Add some dilute starch paste to a test tube half full of 



1 Biuret Test. Add caustic soda in concentrated solution. To this add a 

 few drops of solution of "copper sulphate. A rose-pink color shows the pres- 

 ence of peptones. Violet color indicates the presence of unchanged proteid. 

 SHARPE'S LAB. MAN. 18 



