THE GARDENER. 



11 



rating the ?ap, which, ascending in a crude state, is 

 exposed to the action of I'^glit and air in the lea^es. 

 Important changes are in consequence eifected as re- 

 gards the nature of the sap ; and it is then, in its 

 altered state, thrown into a different system of vessels, 

 by means of which it descends, prepared to add to the 

 organization and development of the plant. In some 

 plants the office of the leaves is performed by the rind 

 and epidermis. 



However obvious it must be to anj observer of ve- 

 getation, that light and air are indispensable to the 

 growth of plants, there are particulars respecting 

 those elements of vegetable life which must be pointed 

 out to the uninstructed mind. For instance, seeds 

 will germinate perfectly in the dark, but the plants 

 arising from them would soon decay if long deprived 

 of light, which, though its inlluence on vegetation is 

 unquestioned, acts in a manner that is mysterious and 

 unexplained. The same great influence causes the 

 colours of fiowers, imparts their perfumes, and gives 

 flavour to theu* fruits ; yet some plants avoid direct 

 light, and, though they cannot exist in darkness, 

 flourish only in the shade. 



Many seeds and buds do not succeed except under 

 a north aspect. Such is the bountiful provision of 

 Providence in organizing plants for every clime and 

 situation ; and is not the study of those peculiarities 

 of structure in vegetables and of their habits most in- 

 teresting to the inquirer, even though for common 

 practice he may dispense with it ? 



Then again as to the influence oi air^ which, after 

 moisture, heat, and light, is the most important agent 

 in forwarding vegetation, there are facts, however 

 plain they may appear, which are subjects of admira- 

 tion and study. Air, that affects the animal frame so 

 powerfully, has a corresponding effect on every blade 

 that grows. It contributes with light to produce 



