194 GENERAL MICROBIOLOGY 



Flask No. l=unheated milk + rennet. 



11 2 = unheated milk + calcium phosphate -f ren- 

 net. 



" ll 3 = heated (sterilized) milk + rennet. 

 " " 4 = heated (sterilized) milk + rennet + calcium 



phosphate. 



6.. Add 1 c.c. of the calcium phosphate solution to one 

 flask of fresh milk and mix. (Flask No. 2). 



7. To each flask of milk add a drop of rennet, shake 

 quickly, replace the flask in the water bath and leave for ten 

 to twenty minutes without disturbing. 



8. Add 1 c.c. of calcium phosphate solution to flask 

 No. 4. Shake quickly, return the flask to the water bath 

 and leave for ten to twenty minutes without disturbing. 

 Observe. If no curd appears, set the flasks at 37 C. and 

 observe after about twenty-four hours. What is the expla- 

 nation for the phenomena occurring in this flask? 



9. Observe the milk in all flasks for curdling. Which 

 flasks of milk curdled? Why? 



10. What are the various synonyms of "rennet?" 

 What is the specific action of this enzyme? 



What is the source of the enzyme used? How prepared? 



What living organisms produce coagulating enzymes? 



Does the rennet produced by various bacteria require 

 soluble calcium salts for an activator? How would you 

 determine this? 



What is an activator? To what property of an activator 

 is its action attributed? What are the different classes of 

 activators? Do all enzymes require activators? 



11. Give all results in full and draw any conclusions pos- 

 sible. What practical applications of the above may be made? 



REFERENCES 



LAFAR: Technical Mycology, Vol. I, pp. 185, 186. 



BAYLISS: Nature of Enzymic Action, pp. 120-121, 132-133. 



RICHMOND: Dairy Chemistry, p. 301. 



EULER-POPE: General Chemistry of the Enzymes, pp. 94, 106-109. 



