IS PLAN 01" VEGEIAXIO:;. 



CHAPTER II. 



TLAJSr or VEGETATION.— ELEMENTARY ORGANS. 



18. The earliest and simplest state of the plant is an eynbrijo 

 contained in a seed. This consists essentially of two parts, the 

 radicle and %>1umule ; the former abont to be developed into the 

 root, the latter into the ascending plant with its appendages. 



19. As soon as the process of germination commences, the 

 radicle begins to extend itself doAvnwards in the direction of the 

 earth's centre, constantly avoiding the air and the hght, forming 

 the descending axis, or root. ,, The plnmide, taking the opposite 

 du-ection, extends itself upwards, always seeldng the light, and 

 expanding itself, to the utmost extent of its power, to the influ- 

 ence of the atmosphere. This constitutes the ascending axis, or 

 trunk, around wliich the leaves and their modifications are 

 arranged. 



20. At the commencement of its gi-owth, the ascending axis 

 is merely a bud, that is, a groiving point, enveloped in rudimen- 

 taiy leaves, or scales, for its protection. As this growing point 

 advances, the enveloping scales expand info leaves below, wliile 

 new ones are constantly appearing, in sudfeession, above. Thus 

 the axis is always terminated by a bud. 



21. By this process the axis is elongated, simply in one direc- 

 tion. But, besides tliis, there is also a bud (or buds), either 

 \'isible, or in a rudimentary state, formed in the axil of each 

 leaf 



a. These axillary buds are generally visible, either before or after the leaf has 

 fallen. In some plants, however, they seldom appear;' hut their existence is 

 inferred from the fact, diat even in such cases, they are occasionally developed in 



extraordinai-y circumstances. 



• ■ ' 



22. Each bud is a distinct individual, capable^trf an independ- 

 ent existence, in favorable circumstances, although severed from 

 the parent stock. 



a. The common practice of pi-opagation by layers, offsets, engrafting, and 

 budding, is both a result and a proof of this principle. A plant may be, and 



