ACTIVATOR FOR ENZYMIC ACTION OF RENNET 193 



How does a scarcity of alcohol influence the amount of 

 acid produced? An excess of alcohol? 



How may vinegar be prepared artificially? How adul- 

 terated? 



7. State the results of your experiment in detail and 

 draw conclusions. Point out any practical applications 

 that may be made. 



REFERENCES 



EULER-POPE: General Chemistry of the Enzymes, 60-61. 

 MARSHALL: Microbiology, pp. 135, 142, 448-451. 

 SADTLER: Industrial Organic Chemistry, pp. 266-272. 

 LAFAR: Technical Mycology, Vol. I, pp. 295-307. 

 Circular on " Vinegar " prepared by Bacteriological Laboratory, East 

 Lansing, Mich. 



EXERCISE 18. TO DEMONSTRATE THE NECESSITY 

 OF AN ACTIVATOR FOR THE ENZYMIC ACTION OF 

 RENNET (FROM CALF'S STOMACH) 



Apparatus. Four clean 200 c.c. Erlenmeyer flasks; 

 sweet skim milk (not over -f!5); rennet, fresh com- 

 mercial; two 1 c.c. pipettes; sterile saturated solution of 

 monobasic calcium phosphate (Ca(H2PO 4 )2+H 2 O); water 

 bath; thermometer. 



Method. 1. Place about 150 c.c. of skim milk in each 

 of two 200 c.c. flasks, plug these and sterilize them by the 

 Tyndall method. 



2. When ready to start the experiment, obtain 300 c.c. 

 of fresh skim milk and place 150 c.c. of milk in each of the 

 two remaining flasks. 



3. Mark the fresh milk flasks Nos. 1 and 2; the sterilized 

 milk flasks Nos. 3 and 4. 



4. Place all four flasks in a water bath and heat 

 the water to 35 C., not higher. (Steam cannot be sub- 

 stituted.) 



5. Mark the flasks as follows : 



