80 LABOEATOKY MANUAL 



them on a white surface and cover them with a weak 

 solution of iodine. In what part of the leaf is starch 

 found? Has chlorophyll anything to do with starch 

 formation ? 



Exercise 50. Making of Food for Plants, continued. 

 Object: To determine the relation of sunlight to 

 starch formation. 



Apparatus 



Nasturtium Iodine 



Alcohol Beaker 



Bunsen burner Evaporating dish 

 Corn starch 



Directions: Place a nasturtium plant in the bright 

 sunlight and another in a dark room. On the after- 

 noon of the second day remove several leaves from each 

 plant, being careful to keep the two sets of leaves 

 separate. Kill them and extract the chlorophyll in the 

 same manner as directed in the preceding exercise. 

 Place the leaves on a white surface and test each for 

 the presence of starch. Is starch found in both sets of 

 leaves? What does this indicate concerning the rela- 

 tion of sunlight to starch making ? 



Exercise 51. By-Products in Food Making. 

 Object: To determine the gas given off when plants 

 make starch. 



Apparatus 



Green water plants Funnel 



Mushrooms Test tube 



Glass jar Pine splinter 



