Leading Principles of the Growth of Trees. 19 



ceases to grow till new ones expand; and if often repeated it 

 perishes. When the leaves of young pear-stocks cease to act, in 

 consequence of leaf-blight, the tree no longer grows ; cambium 

 ceases to form, and they cannot be budded. An interesting illustra- 

 tion of the office of leaves occurred to the writer a few years since : 

 A yellow gage plum-tree set a heavy crop ; but when the fruit was 

 nearly grown, all the leaves dropped. The fruit remained green, 

 flavorless, and stationary, until a new crop of leaves came out. It 

 then finished growing, acquired a golden color, and a rich, excellent 

 flavor. 



Perfect fruit requires perfect leaves ; and thick, crowded, half- 

 grown leaves, give small fruit with poor flavor. The great object of 

 pruning, and of summer pruning especially, is to give plenty of 

 good, healthy, and not crowded foliage, and the crop will also be 

 good. 



The green bark of trees and plants performs an office similar to 

 that of the leaves ; and in connection with the cells adjoining, ap- 

 pears to fulfil sometimes an office which the leaves fail to accom- 

 plish. This is, preserving the identity of the species or variety. 

 For example, bud a^tetfr-tree on a quince. All the wood above the 

 place of union will be pear-wood ; all below will be quince. All the 

 supplies which come from the pear-leaves change to quince-wood 

 the moment they pass this point ; and if the budding is performed 

 when the quince-stock is smaller than a quill, yet all the wood 

 below, when it becomes a large tree, will still be perfect quince- 

 wood, as is shown when any chance shoots or suckers spring up 

 from below. Or bud, for example, the Northern Spy, which has 

 dark bark, with the Bellflower, which has yellow ; and again, bud 

 the snow-apple, which has dark-colored bark, on the Bellflower, and 

 the light-colored Sweet Bough on this each being an inch above 

 the last budding. Successive dark and light bark, the peculiarity of 

 each variety, will remain as long as the tree grows ; showing con- 

 clusively that the bark performs the finishing process in the manu- 

 facture of the new wood. 



FLOWERS. 



The object of the flower is the production of seeds, and through 

 them the reproduction of new plants. The protecting organs of 

 each are, the calyx outside, which is usually, not always, green ; and 

 the corolla, or flower leaves, of various colors, which are next within 



