NODES AND INTERNODES. BUDS. 95 



internodes appear, and by their elongation separate them, and so 

 carry upward the stem. To have a good idea of this, we have 

 only to observe the gradual evolution of a germinating plant, where 

 each internode developes nearly to its full length, and expands the 

 leaf or pair of leaves it bears, before the elongation of the succeed- 

 ing one commences. The radicle, or internode which preexists 

 in the embryo (118) elongates, and raises the seed-leaves into the 

 air (Fig. 107) ; they expand and elaborate the material for the 

 next joint, the leaves of which in turn prepare the material for the 

 third (Fig. 102-104), and so on. The internode lengthens princi- 

 pally by the elongation of, its already formed cells, particularly in 

 its lower part, which continues to grow after the upper portion has 

 finished. 



144. Buds. The apex of the stem, accordingly, at least of every 

 stem capable of further terminal growth, is always crowned with 

 an undeveloped portion, the rudiments of parts similar to those 

 already unfolded, that is, with a BUD (113). The embryo itself 

 may be rightly viewed as the fundamental bud borne on the apex 

 of the radicle or original internode, from which the whole plant is 

 developed ; just as an ordinary bud of a tree or shrub developes 

 to form a year's growth. Except that, in the latter case, the differ- 

 ent steps follow each other more closely ; for the bud usually 

 has a considerable number of parts ready formed in miniature be- 

 fore it begins to grow, and has a full store of assimilated sap accu- 

 mulated in the parent stem to feed upon. Such buds, which 

 appear at the apex of a stem when it has completed its growth for 

 the season, often exhibit the whole plan and amount of the next 

 year's growth ; the nodes, and even the leaves they bear, being 

 already formed, and only requiring the elongation of the inter- 

 nodes for their full expansion. The structure is shown in the an- 

 nexed diagram (Fig. 126), which represents the vertical section of a 

 bud (like that which crowns the stem in Fig. 127), as it appears in 

 early spring. As the bud is supplied by the stem on which it rests 

 with nourishment sufficient for its whole development, it elongates 

 rapidly ; and although the growth commences with the lowest 

 internode, arid follows the same course as in the seedling, yet the 

 second, third, and fourth internodes, &c., have begun to lengthen 

 long before the first has attained its full growth ;. as is attempted 

 to be shown by the diagram, Fig. 128. The stem thus continued 

 from a terminal bud is, if it survive, again terminated with a sim- 



