648 Mr. Spencer U. Pickering [Feb. 21, 



the trees cannot be made to take these shapes without assistance by 

 pruning ; and this brings us to a sul)ject on which many experiments 

 have been made at Woburn. We will not, however, start quite so 

 far back as the pruning which is necessary to make a tree take the 

 form of a standard, but begin at the point where the tree has been 

 removed from the nursery to the plantation, generally at an age of 

 two to four years. During such removal many of the roots are 

 destroyed, and nearly all of them are injured. The seat of growth 

 of a root is situated at the extreme tip of the root, the power of 

 multiplication being confined to a few meristematic cells which are 

 centred there, these being protected only by some layers of outer 

 cells, known as the root-cap, which are continually being rubbed off, 

 and reproduced from the meristematic cells, as the root forces its 

 way through the earth. [Slide shown.] The whole root-tip is very 

 minute, and when it is destroyed, growth becomes impossible ; but 

 there are certain cells situated at intervals along the roots which are 

 capable of becoming modified and giving rise to new root-tips, just 

 as there are cells in the branches capable of developing into buds 

 if all the visible buds of a tree are destroyed. 



When a tree is removed from the soil, most of the root-tips will 

 inevitably be broken off, and the rest will become dried up by expo- 

 sure to the air, so that the damage to the roots must be serious. 

 But the well-being of a tree depends on the balance between roots 

 and branches, both of which supply certain, but different, elements 

 necessary for growth, and this serious damage to the roots can only 

 be counterbalanced by damaging the branches to a corresponding 

 extent. This is done by severely pruning the branches, cutting them 

 back, as it is termed, to about one-third of their length. The effect 

 of omitting this operation is often disastrous ; the tree may become 

 permanently stunted, and even, in the case of plums, which tend to 

 bear heavily after moving, it may be fatal. The general effect is to 

 arrest all growth for the first year, while the branches bear leaves 

 little more than half the size they should be, and incapable of 

 functioning properly. [Slide shown.] 



Though good horticulturists agree as to the necessity of cutting 

 back after transplanting, they differ as to the time when this should 

 be done, some advocating its being done at once, others deferring it till 

 the spring, and others, again, postponing it till one year after planting. 

 The results of our experiments on a large number of trees show that 

 the time of cutting back makes little difference to the ultimate size 

 of the tree so long as it is not performed while the tree is in active 

 growth. If it is done in the summer, however, the tree receives a 

 serious check from which it does not recover for at least the next 

 seven years. [Slide shown.] Deferring the cutting back till the 

 following winter does not give the tree any such check as regards its 

 growth, but it affects its fruiting. Such deferred cutting back is 

 generally followed in tne second year by vigorous growth, the tree 



