60 GROWTH OF PLANTS -^- GRAFTING. 



the new branches. These young shoots are, in general, protected 

 in their first growth by peculiar scales, and then constitute what 

 are called buds. They are ordinarily found at the base of the 

 petioles of the leaves, or at the extremity of the branches in 

 ligneous plants, and at the collum or neck of the root in perennial 

 herbaceous plants. Sometimes they are not apparent externally, 

 and are concealed even in the substance of the wood : but in 

 most instances they have the form of a small projecting tubercle, 

 which shows itself in the summer, and is known to farmers under 

 the name of eye; during the winter they enlarge, and in the 

 spring, when the sap begins to rise with strength, and to carry 

 towards the extremity of the branches the nutritive matters pre- 

 viously deposited in the roots or in the stem, they rapidly develope 

 themselves, their scales separate, and we see a young branch 

 spring from them, the leaves of which are at first variously 

 plaited and very close together ; this new shoot grows more 

 rapidly in proportion to the abundance of the sap, and during a 

 certain time is elongated throughout its length. But after the 

 first year it ceases to grow in this way, and it then forms laterally, 

 and particularly towards its upper part, new layers of vegetable 

 tissue which contribute to the increase of the length of its ex- 

 tremity, and, at the same time, to augment the diameter of its 

 base. 



68. In endogenous trees growth takes place very nearly in the 

 same manner, only the new parts do not form concentric layers, 

 but simply bundles (fasciculi) of fibres variously arranged, and 

 the buds are ordinarily developed at the extremity of the stem 

 and branches. 



69. We have said above that the cells of the cellular tissue, 

 when very young, tend to become united or soldered to each 

 other. This is so true that if we lay bare a portion of new 

 tissue of two neighbouring trees, and bring these parts together 

 and keep them in contact, they become so intimately united that 

 the two soon form a single body, and possess one life in common. 

 The art of grafting plants depends upon a knowledge of this 

 fact. * 



[Grafting is an operation by which one plant is joined to another in vital 

 union, in such a manner as to form one. The tree upon which grafting is 

 practised is called the stock, and the branch, or rudiment of a branch that 

 is fitted to it, is named the graft. The stock is ordinarily a wild shrub, 

 and the graft a cultivated variety of the same plant. In order to succeed, 

 the albur'num of the graft must accurately fit, through the greatest part of 

 its extent, that of the stock, that is, the tree upon which the graft is im- 

 planted ; then the junction, or, as it were, soldering of the two barks, is 



6. How does the growth of en'dogens differ from that of ex'ogens ? 

 69. tpon what does the art of grafting depend? What is grafting? 

 \Vhat are the modes of performing this operation ? 



