XII. THE DIGESTION OF STARCH: TRANSLOCATION 



A. The Starch-content of Leaves During the Day and at 

 Night: 1 



Experiment 31. To find out if starch is present in 

 leaves gathered in darkness as well as in light. 



1. Dechlorophyllized leaves of clover (or of one of the 

 first five plants listed in the table in the foot-note 

 below), collected (a) in bright sunlight, (b) several 

 hours after sunset, will be tested by the instructor 

 for the presence of starch. . 



2. Did both leaves probably contain starch during 

 the day? From this experiment what do you 

 know has taken place in the leaf gathered at night? 

 Is starch soluble? What, then, must have occurred 

 to the starch? 



1 Miss ECKERSON (Bot. Gaz., 48: 224-228. 81909) recommends the 

 following plants for this study, since in them photosynthesis is very ac- 

 tive, starch disappears from their leaves in darkness with comparative 

 rapidity, chlorophyll is easily extracted, and the iodine reacts quickly: 



48 



