71 



CHAPTEE X. 



THE LEAVES OF PLANTS. 



The chief Ornament of Spring. Internal Structure of Leaves. The Cuticle. 

 Stomata and Air-Cells. Opening and Closing of the Stomata. Pliability and 

 resisting Powers of the Leaves. Their Stems. Dionsea Muscipula. The 

 Mimosas. Enemies of the Leaves. Their Defences. Hairs. Prickles. 

 Secretions. Harmonies between Leaves and Insects. 



How beautiful the lively verdure of spring, how it refreshes 

 the eye after the gloom of winter, and where shall we find in 

 summer a more delicious shade than under the green canopy of 

 the woods ? As the year declines, the autumn tinges the forests 

 with the richest colours ; and even in winter, the dark evergreens 

 form a picturesque contrast with the dazzling snow, so that at 

 all seasons of the year the landscape is adorned by the foliage 

 of the trees. 



Were the leaves restricted to a few simple forms, to a small 

 number of tints, they would still be one of the chief ornaments 

 of Nature ; but their decorative power is wonderfully enhanced 

 by their endless varieties of shape, by their infinite shades of 

 colour. Of all the herbs we may gather on our excursions, not 

 one is like the other ; every new species of tree that meets our 

 eye has its own peculiar foliage, and were we to wander through 

 all the zones of the earth, every new plant on our way would 

 greet us with a new form of leaf. 



Thus, the delicate organs of vegetable life have been made, 

 not only to minister to the wants of the plants of which they 

 form a part, but also to afford a constant gratification to our 

 sense of the beautiful, and to raise the mind by the delight 

 which their every varying contrasts afford, to Him who made 

 them. 



Conjointly with the roots, the leaves serve to nourish the 

 plant ; they inhale and elaborate the gases and vapours of the 



