4 



GENERAL PEINCIPLES. 



under, or in direct connection with the largest branches, 

 will have a corresponding size and vigor. In cases where 

 one side of the top of a large tree is cut off, as in top 

 grafting, a large number of new shoots are produced on 

 the cut branch, and, if the roots be examined under or 

 in connection with this branch, a corresponding new 

 growth will be found there. It is quite obvious from 

 these and similar facts, that whatever affects the roots or 

 stems of trees favorably or unfavorably, affects the whole 

 tree. ' If the foliage of a tree be entirely removed in the 

 growing season, the absorbent action of the roots is sus- 

 pended ; and if the spdngioles or absorbing points of the 

 roots be cut off, the growth of the fop instantly ceases. 

 Those who have leisure should pm-sue the study of these 

 highly interesting and important points still further. 



Section 2. — ^The Stem. 



The Stem is that pai-t of a tree which starts from the 

 collar and grows upwards. It sustains all the branches, 

 and forms the channel of communication between the 

 different parts of the tree from one extremity to the other. 



Plants like the grape, with twining or climbing stems, 

 are called vines^ and such as have no main stem, but have 

 branches diverging from the collar, as the gooseberry, cur- 

 rant, &c., are called shrubs or hushes. Where the stem is 

 destitute of branches to some distance from the ground, 

 it is usually called the trunk. 



Different Parts of the Stem. — A stem or branch of a 

 tree is composed of the following parts, which are dis- 

 tinctly observable when we cut it across. Fig. 2 repre- 

 sents the half of a cross section of the stem of a young 

 tree five years old. 



1. The Bind or Outer Ba/rk {A) on shoots or young parts 

 of trees ; this is thin, smooth, and delicate, like tissue 



