THE WORK OP LEAVES 91 



Set the plant in the sunlight, and after it has been there 

 several hours, remove the leaves to which the corks are 

 attached. Remember that the exclusion of light from the 

 portions of these leaves between the corks has probably 

 put a stop to the work of starchmaking there. 



Place the leaves of the plants in a dish of water and 

 boil them for about one minute to break down the tissues. 

 Transfer them to a bottle of alcohol. Cork tightly and 

 set away for a day or more. If this does not remove 

 the green coloring matter, transfer them to a dish of al- 

 cohol and boil them in it until the coloring matter is dis- 

 solved and the entire leaf is white. In this case, use the 

 utmost care that your alcohol does not boil over, take 

 fire and bum up your leaves. 



Now put the leaves into some tincture of iodine, diluted 

 with water. Allow them to remain in this solution three 

 or four minutes. Remove and wash them with fresh 

 water and spread them out on clean sheets of paper. 



Test fine pieces of potato, crushed corn and powdered 

 rice or wheat flour for starch. Tell how and where this 

 starch was manufactured. 



Conclusion. — Describe fully the results secured with 

 the leaves and explain. If weeds, or other plants, cut off 

 the sunlight from growing plants, what part of the " mill " 

 indicated in Figure 29 is shut off? Why are plants which 

 are crowded often spindling in growth? Why do sprout- 

 ing potatoes in the cellar grow toward the light of the 

 window? 



67. How Other Foods are made. — The starch, manu- 

 factured in the green leaves, is one of the chief food mate- 

 rials of the plant, but it is of the utmost importance for 

 still another reason. With starch as a basis, the plant 

 makes many other kinds of foods, such as sugars, fats. 



