380 SYLVA AMERICANA. 



the contents of wood which had been periodically formed by the 

 branch or branches thus separated from the stem. 



When branches are not allowed to perfect one year's growth, 

 but are pruned off annually within a bud or two of their origin 

 with the stem, they act rather as organs of waste than those of 

 increase of wood to the stem. But although the rate of periodical 

 increase of the diameter of a tree be thus lessened, in a certain 

 extent, by the loss of a full-grown lateral branch, yet the increase 

 of the stem in height or length is not thereby retarded, the ligneous 

 vessels of the root corresponding with those of the stem or wood, 

 probably act with but little diminished force in sending up 

 sap to the higher extremities of the tree. 



It is of great importance that branches which indicate an over- 

 luxuriant growth should never be suffered to become large, or to 

 exceed the medium size of the majority of the boughs of the 

 tree, but should be pruned off close to the stem when the general 

 interests of the plant will admit of it. These over-luxuriant 

 branches, which, when suffered to take the lead in growth of the 

 general boughs, become so hurtful to the perfection of growth of 

 the stem, are evidently produced and supported by the accidental 

 circumstance of a superior portion of soil being in the way of, 

 and into which the roots immediately connected with these 

 boughs penetrate and afterwards keep possession. By taking 

 off such branches early, therefore, the extra supply of nourishment 

 afforded by such local circumstance of soil is directed to the stem 

 and useful lateral branches. 



By depriving a tree, to a certain extent, of its side branches, 

 the growth of the stem in length is promoted, but the diameter, 

 strength, or thickness of it is not increased in the same proportion. 

 When the side branches are destroyed by natural causes, or by 

 the neglect of judicious thinning, the like injurious effects ensue 

 to the primary object here in view, that of obtaining the largest 

 quantity of timber of the best quality on a given space of land. 



When the lateral branches perish or cease to be produced, 

 except towards the top of the tree, from the want of pure air and 

 of the vital influence of the solar rays on the foliage, the existence 

 of the tree may continue for years, but the produce or increase 



