50 PRINCIPLES OF GARDENING. [CH. 11. 



in the spring. Hence the reason that plants are 

 transplanted with most success during the season of 

 their decay : for, as the root almost exclusively im- 

 bibes nourishment by the mouths of these fibres, in 

 proportion as they are injured by the removal, so is 

 the plant deprived of the means of support ; that 

 sap which is employed in the formation of new 

 fibres, would have sensed to increase tlie size of 

 other parts. 



The quantity of root I have always observed to 

 increase with the poverty of the soil in which it is 

 growing. Duhamel found the roots of some young 

 oaks in a poor soil to be nearly four feet long, though 

 the stem was not more than six inches. Every one 

 may have noticed this familiarly instanced in Poa 

 annua growing on a gravel walk, its stem minute, its 

 root a mass of widely extending fibres. The cause 

 of this is evident : the nourishment which is required 

 for the growtli of the plant, can only be obtained by 

 an increased, widely extending surface of root, and, 

 to form this, more sap is often required than the 

 plant, owing to the poverty of the earth, can obtain 

 for itself ; in that case, a soil is sterile, for the plant 

 must evidently perish. 



A root always proceeds in that direction where 

 food is most abundant, and, from a knowledge of 

 this fact, we should be circumspect in our mode of 

 applying manures, according to the crop and object 



