LEAF-BUDS. 125 



8S. They are organs capable of propagating the individual from which 

 they originate. 



89. They are at first nourished by the fluid lying in the pith, but finally 

 establish for themselves a communication with the soil by the woody mat- 

 ter which they send downward. 



90. Their force of developement will be in proportion to their nourish- 

 ment ; and, consequently, when it is wished to procure a young shoot of 

 unusual vigour, all other shoots in the vicinity are prevented growing, so 

 as to accumulate for one shoot only all the food that would otherwise have 

 been consumed by several. 



91. Cutting back to a few eyes is an operation in pruning to produce the 

 same effect, by directing the sap, as it ascends, into two or three buds only, 

 instead of allowing it to expend itself upon all the others which are cut 

 away. 



92. When leaf-buds grow, they develope in three directions ; the one 

 horizontal, the other upward, and the third downward. 



93. The horizontal developement is confined to the cellular system of the 

 bark, pith, and medullary rays. 



94. The upward and downward developements are confined to the woody 

 fibre and vascular tissue. 



95. In this respect they resemble seed ; from which they differ physio- 

 logically in propagating the individual, while seed can only propagate the 

 species. 



96. When they disarticulate from the stem that bears them, they are 

 called Buds. 



97. In some plants, a bud, when separated from its stem, will grow and 

 form a new plant if placed in circumstances favourable to the preservation 

 of its vital powers. 



98. But this property seems confined to plants having a firm, woody, 

 perennial stem. 



99. Such buds, when detached from their parent stem, send roots down- 

 ward and a stem upward. 



100. But if the buds are not separated from the plant to which they 

 belong, the matter they send downward becomes wood and liber {66), and 

 the stems they send upward become branches. Hence it is said that wood 

 and liber are formed by the roots of leaf-buds. 



101. If no leaf-buds are called into action, there will be no addition of 

 wood ; and, consequently, the destruction or absence of leaf-buds is accom- 

 panied by the absence of wood ; as is proved by a shoot, the upper buds 

 of which are destroyed and the lower allowed to develope. The lower 

 part of the shoot will increase in diameter ; the upper will remain of its 

 original dimensions. 



102. The quantity of wood, therefore, depends upon the quantity of 

 leaf-buds that develope. 



103. It is of the greatest importance to bear this in mind in pruning 

 timber trees : for excessive pruning must necessarily be injurious to the 

 quantity of produce. 



104. If a cutting with a leaf-bud on it be placed in circumstances fitted 

 to the developement of the latter, it will grow and become a new plant. 



105. If this happens when the cutting is inserted in the earth, the new 

 ^lant is said by gardeners to be upon Us own bottom. 



11* 



