4jJ VEGETATION. 



the valley, while others bud and bloom only on the 

 mountain's dreary summit. From water, air and the 

 soil, plants derive their food ; heat and light enabling 

 them to convert it to their own use. 



1. WATER. — Of the various substances by which 

 vegetables are nourished, water is perhaps the most 

 important. It preserves the vigour and freshness of 

 plants, which droop and wither when deprived of their 

 necessary supply, and it restores to health the leaf 

 that fades in consequence of its privation. * " Many 

 plants will grow, and thrive, and effect the develope- 

 mentof all their parts, if the root is merely immersed 

 in water, though not fixed in the soil. Lilies, Hya- 

 cinths, and a variety of plants with bulbous roots, may 

 be so reared, and are often to be met with, so vegeta- 

 ting ; and others will also vegetate, though wholly im- 

 mersed. Most of the marine plants are of this descrip- 

 tion. It can scarcely be doubted therefore, that water 

 serves for the purpose of a vegetable aliment. 



But if plants cannot be made to vegetate without wa- 

 ter ; and if they will vegetate, some, when partly im- 

 mersed, without the assistance of soil ; and some, even 

 when totally immersed, so as that no other food seems 

 to have access to them ; does it not follow that water 

 is the sole food of plants, the soil being merely the ba- 

 sis on which they rest, and the receptacle of their 

 food ? This opinion has had many advocates ; and the 

 arguments and experiments adduced in support of it, 

 were at onetime thought to have completely establish- 

 ed its truth. It was indeed the prevailing opinion of 

 the seventeenth century, and was embraced by sever- 



« This chapter is selected chiefly from the Physiological Bota- 

 nv of Mr. Koith. 



