478 CONSERVATIVE ORGANS. [t,ECT. IX. 



verdant vale, and the massive luxuriance of the 

 darkened forest. The most beautiful flower loses 

 half its charms when it is displayed on a naked 

 stem; the miserable hovel becomes picturesque 

 when spread over with the foliage of the Vine ; 

 the ruins of former magnificence acquire more 

 reverence, and command a double share of our 

 respect, when seen through the tracery of the 

 Ivy; and the horrors of the frowning rock are 

 softened into beauty when mantled with pendent 

 creepers or with Alpine shrubs. Leaves are still 

 more important when we regard them as af- 

 fording food to man and the rest of the animal 

 creation; and supplying medicinal agents to re- 

 lieve their sufferings in disease. Notwithstanding, 

 however, the interest which they thus excite ; and 

 our familiarity with leaves, as objects of sight, from 

 our earliest years, it is impossible to form an un- 

 exceptionable definition of the leaf. This difficulty 

 arises from the great diversity of figure, substance, 

 surface, and colour which it assumes in different 

 plants. If we cannot, therefore, define it accu- 

 rately from its external characters, we must have 

 recourse to its functions; and perhaps the following 

 is the least exceptionable definition we can offer : 

 The leaf is, a temporary organ of plants., which 

 performs nearly the same function in the economy 

 of vegetable life as the lungs perform in that of 

 animal life : or, in fewer words, leaves are the 



