THE EOOT. 3 



paradise apple, used as a stock for dwarf trees, and tlie 

 quince, are always quite fibrous, the former never, and 

 the latter seldom requiring root pruning. 



5th. Tlie spongioles are the extremities of the fibres, 

 porous and spongy, through which the food of trees de- 

 rived from the soil is mainly absorbed ; these points are 

 composed of soft, newly-formed, delicate tissue, and are 

 exceedingly susceptible of injury. The slightest bruise or 

 exposure to a dry or cold air is fatal to them ; and this 

 is the reason why trans23lanted trees receive generally 

 such a severe check and so frequently die. If trees could 

 be taken up in such a way that these spongioles could all, 

 or mostly, be preserved, trees would receive no check 

 whatever ; hence large trees are removed in midsummer 

 without a leaf flao-o^ina^. 



6tb . Growth of Boots. — The most popular theory at this 

 time is — that the growth of roots is produced by the pro- 

 longment of the woody vessels of the stem, wdiich descend 

 in successive layers to the extremities of the roots, and 

 thus promote their extension. 



When these descending layers are interrupted in their 

 course by some natural or accidental cause, or by art, as 

 when we cut off the ends of roots, they pierce the bark 

 and form new roots or new divisions of the root in the 

 same manner that branches are produced on the stem. 

 Thus the roots furnish food to the stem and branches for 

 their support and enlargement, and in return, the stem and 

 branches send down layers of young wood to increase and 

 solidify the root ; the one depending entirely upon the other 

 for its grow^th and existence. Practical cultivators are 

 familiar with many facts that illustrate the intimate rela- 

 tions and mutual dependency of the roots and stems. 

 For instance, where one portion of the head or branches 

 is much larger or more vigorous than the other, if the 

 roots be examined, it will be fomid that those immediately 



