TRANSPIRATION. 157 



for pumping it up from the roots as land-plants 

 possess. 



The stomata are of course a great deal too small 

 to be seen without a microscope, but there is a 

 way in which we can tell on which side of any 

 leaf they are to be found. Dip the leaf in water, 

 and, after holding it there for some time, take it 

 out and shake it. Wherever a film of water 

 covers the leaf, there are no stomata ; but where 

 the leaf is dry, there they will be sure to be found. 1 

 It would be an injury to the plant to have its 

 breathing pores clogged with water. Therefore 

 the surface where the stomata are is protected in 

 various ways from the wet. Many leaves have 

 what we call "bloom" upon them. This is a 

 waxy coating which prevents the rainwater from 

 adhering to the leaves. It can be observed on the 

 leaves of Cabbage, Nasturtium, Castor Oil Plant, 

 Begonias, and Primroses. The beautiful Gold and 

 Silver Ferns in our conservatories have the lower 

 side of their leaves covered with a sort of yellow 

 or white meal, which answers the same purpose. 



Another mode of protection is through the help 

 of hairs. A countless number of leaves of our 

 common plants are covered with fine hairs, and 



i Pflanzenleben," Vol. I. p. 267. 



