120 THE CANADIAN NATURALIST. [April, 



It is now easy to understand that forest-trees and other peren- 

 nial plants, growing slowly but continuously, year after year, and 

 possessing a comparatively vast expanse of foliage and of roots, can 

 thrive in soils less rich in mouldering humus, and therefore in 

 carbonic-acid gas, than is needful for certain annuals, — such as, 

 for instance, the wheat-plant, — whose term of existence is brief, 

 whose foliage scanty, whose roots small (especially during the ear- 

 lier stages of its development), and whose growing power is of a 

 proportionately delicate quality. In this latter case, art may use- 

 fully intervene to concentrate, within narrower limits of time and 

 space, the supply of carbon diiFused by nature over a more extend- 

 ed area and a longer term. This explanation justifies, in the case 

 of wheat and similar crops, additional supplies, not only of carbon, 

 but also of other forms of plant-food ; and it leads to the con- 

 sideration of " high farming," its objects, its dangers, and its 

 normal limits, — which may, however, be conveniently reserved 

 for brief elucidation further on. 



Supply of Water to Plants. — Meanwhile a few remarks 

 are due to the plant-food next in order of weight to carbon ; viz., 

 to hydrogen and oxygen ; which are supplied to plants in combi- 

 nation with each other, as water. 



The source of this aliment is too familiar to need even indication 

 here. Yet the natural mechanism by which water is distributed 

 to plants, in the form of rain and dew, is too wonderful and beau- 

 tiful to be passed in silence. Shakespeare, who always arrived at 

 truth through beauty, was struck with the all-pervasive difi"usion 

 of rain, and with the admirable tempering of its descent by the 

 atmospheric resistance. Its soft fall upon the unruffled foliage 

 symbolized for him Mercy's sweet grace and " unstrained quality," 

 whereof he savs, 



" It droppeth as the gentle rain from heaven 

 Upon the plants beneath."* 



Shelley too, personifying the Cloud, sings beautifully : 



" I bring fresh showers for the thirsting flowers 

 From the seas and the streams." 



A volume of prose could scarcely express with more precision and 

 completeness than these four lines the philosophy of the aqueous 



* This is commonly printed "upon the 'place, beneath."' But as 'place 

 cannot be effected bj the gentleness of rainfall, and plants can, the lat- 

 ter seems the more likely to have been Shakespeare's word. 



