22 



COMPOUND ORGANS OF PLANTS. 



thus prepared will exhibit these pores, and the nature and 

 beauty of their mechanism will be seen and appreciated. 



The stomata are generally found on the under surface of the 

 leaves, the mechanism being too delicate to act well in direct 



Fig. 3. 



Epidermis of the lily, showing the stomata st, composed of two cells with an o; en- 

 ing or slit between them. 



sunshine. They are invariably absent from the parts of plants 

 growing beneath the water. The water-lilies (Nuphar and 

 Nymphrea,) and all plants whose leaves float on the water, 

 have the stomata on the upper surface of their leaves. If the 

 leaves of plants grow erect, the stomata. are equally distributed 

 on both sides. 



Stomata are more or less abundant on the cuticle of all 

 plants', and as these pores perform the functions of exhalation 

 in proportion to their number on different plants, it is neces- 

 sary to supply them with water. The plant called Hydrangea 

 quercifolia has on one square inch of its surface 160,000 pores, 



