190 THE INCOME OF ENERGY 



Eed cuprous oxide or its yellow hydrate will 

 separate. 



The germinating barley causes the starch to 

 take up water, thus changing to a reducing sugar. 

 In this instance the agent is a living cell, or 

 some substance or " ferment " secreted by the 

 cell. It is now necessary to inquire whether 

 ferments are separable from living cells. 



Conversion of Starch to Sugar by Salivary Dias- 

 tase (Ptyalin). To 10 c.c. of starch paste 1 col- 

 ored blue with iodine (blue iodide of starch) add 

 about 2 c.c. of filtered saliva and keep the mixture 

 at 35-40 C. 



The starch paste will liquefy and become sweet. 

 The blue color will become lighter and finally 

 disappear. 



Test with Fehling's solution. Eeduction will 

 take place. 



Saliva hydrolyzes starch to a reducing sugar. 



Saliva is secreted by the cells in the salivary 

 gland, placed some distance from the mouth. 

 The saliva itself contains no secreting cells. 

 There are ferments, then, which act at a distance 



1 Starch paste. Rub 1 gtn. potato starch in a mortar with 

 25 c.c. cold water. Pour the mixture into an evaporating dish. 

 Wash the remnant from the mortar and pestle into the dish with 

 75 c.c. water. Heat the mixture to boiling point with constant 

 stirring. The starch paste will turn blue upon addition of iodine 

 (iodide of starch). 



