vin ENZYMES 163 



Conclusions : 



Invertine is an enzyme, and therefore not destroyed 

 by chloroform. 



The alcohol -producing ferment is a living ferment, 

 and as such is destroyed by chloroform. 



C. ACTION OF MOIST HEAT ON ENZYMES. 



(1) Prepare a suspension of yeast in lukewarm sterile 

 water. 



(2) Shake up a little of it with chloroform as above, and 

 allow the chloroform to settle. 



(3) Separate the supernatant liquid, and pour a little of 

 it into two test-tubes. 



(4) Heat one of them up to boiling point, leaving the 

 other for control. 



(5) Add some of the boiled suspension to two tubes con- 

 taining a dilute solution of cane sugar, and keep the tubes 

 at 38-5 C. 



Test one tube with Fehling's solution after four to 

 six hours : no reduction of copper and no alcohol. 



Test the other tube with Fehling's solution after 

 twenty-four hours : no reduction of copper and no 

 alcohol. 



(6) Add some of the suspension in the control tube to 

 two tubes containing a dilute solution of cane sugar, and 

 keep the tubes at 38 -5 C. 



Test one tube with Fehling's solution after four to 

 six hours : marked reduction of copper. 



