EXERCISE 54 



Problem. How does water get out of the leaf ? 



What to use. A compound microscope ; a coleus or geranium leaf ; slides ; cover glasses ; water. 

 What to do. Strip a small piece of the lower epidermis of the leaf, mount in water on a slide, place 

 a cover slip over the preparation, and examine both through low and through high power. 

 Record. Make a careful drawing of what you see ; 1 label all you can make out. 



Questions. 1. Can you suggest an advantage of the location of stomata on the under surface of 

 the leaf ? 



2. Where would you look for the stomata of a lily pad ? 



NOTE. Cross sections of leaves show enlarged spaces just inside the stomata. Water evaporates into these spaces from 

 the leaf cells, and the vapor diffuses out through the stomata. 



1 The special arrangement of cells leaving an opening in the skin is called a stoma, meaning mouth (plural stomata). The 

 large cells surrounding the stoma are called guard cells. The stomata allow air to pass in as well as water (vapor) to pass out. 



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