BTIDS AND BLANCHES. 69 



the same law as that which governs the arrangement and 

 position of the leaves. If the leaves be opposite, the 

 branches will be opposite ; if the leaves be alternate, the 

 branches will be alternate ; and so on. This symmetrical 

 arrangement of the branches is interfered with and obscured by 

 the operation of the following causes : — 



The non-development of some of the axillary huds. — As the 

 primary plant is only called forth from seed by certain condi- 

 tions of heat, light and moisture favorable to its development, 

 without which it remains latent in the seed, so the branches 

 only protrude from axillary buds when circumstances are 

 favorable, otherwise the buds remain latent on the stem, and 

 no branches proceed from them. Now many of the buds in 

 the axils of the leaves do not grow ; because their growth is 

 checked by the rapid growth of some few leading buds, which 

 monopolize all the nutriment, leaving them only just sufiSoicnt 

 to carry them forward with the increasing thickness of the stem, 

 and to maintain their position on its surface, where they remain 

 ready for action in case the growth of the other buds is checked 

 by untimely frost, or other causes. In this manner, trees, 

 whose young and tender foliage and branches has sustained 

 injury by the cold in early spring, soon become re-clothed with 

 verdure. On this principle, also, trees are pruned and trained 

 against walls, or other supports. Certain leading shoots and 

 buds are cut, in order that the supply of sap they were mono- 

 polizing may flow to certain lateral and latent buds, and cause 

 their growth in the proper direction. In general the sap has 

 tendency to rise in greater force and abundance towards the 

 extremity of the branches, . the result of this is that the inferior 

 leaves are the first to become detached from the branches, and 

 their buds not receiving enough nourishment to bring them to 



7 



