16 



INTEODUCTION. 



[14. 



ascends, seeking the air and light, and expanding 

 itself to their influence. This constitutes the 

 stem or ascending axis, bearing the leaves. 

 Thus the acorn germinates, and the Oak en- 

 ters upon the second stage of its existence. 



33. At first the ascending axis is merely 

 a bud, that is, a growing point clothed with 

 and protected by little scales, the rudiments 

 of leaves. As the growing point 

 advances and its lower scales grad- 

 ually expand into leaves, new scales 

 successively appear above. Thus 



the axis is always terminated by 

 bud. 



34. The terminal bud ex- 

 pands into leaves, and the 

 ascending axis (Fig. 4, p) 

 creases in length and diam- 

 eter. Besides the terminal 

 bud, one is formed in the 

 axil of each leaf. If none 



of the buds in the 

 axils of the leaves de- 

 velop, the plant at 

 the end of the grow- 

 ing season will pre- 

 sent a young oak, as 

 Fig. A, but if one should grow, the little tree would 

 appear as in Fig. B. 



35. During successive periods of growth the lateral 

 buds develop, forming branches and branchlets, and 

 season after season the main axis lengthens and in- 

 creases in diameter, the branches multiply and enlarge, 



m- 



Acorn (seed of Quercus) germinat- 

 ing ; 1, section showing the radicle (?) 

 which is to become the root, and the 

 two cotyledons (c) which are to nourish 

 it ; 2, the radicle r, descending ; 3 and 4, the radicle, r, de- 

 scending, and the plumule (p) ascending. 



