PRINCIPLES OF VEGETATION, ETC. 117 



fissure and dii'ects itself downwards into tlie earth ; the plumule D erects 

 itself, is disengaged from the shell, and becomes the stem, while the coty- 

 ledons furnish food to the young plant, until the first leaves develop them- 

 selves and the spongioles of the roots are capable of receiving nourishment 

 fx'om the earth. 



'253. In plants with a soft covering, as the bean, the radicle A is directed 

 cO the outside of the seed, — it is the rudi- 

 ment of the root : this is the first part ^.^-^^ •^"^"\. 



which develops itself in germinating. The /^ \ \ f'^' ^ ^r -C 



plumuleB, on the con trar}', ascends towards / ((^(' L_>. / ti^L^^ \ 



the centre of the grain, and becomes the ru ^rr^. ._Xi^^^l_ \ 33 



stem, while the two cotyledons C remain in \\\i; — ' /(MfjaTf . "^ — j 



the soil between the root and the stem, \\k— ^''''fi''M(l"\rv^^ -^ 



yielding nourishment to the young plant ^^^^ ^ ^^ \^ 

 until the roots can perform that office. 



254. It is found, however, that except in the case of annuals (as plants 

 raised from seed, which grow, produce their seeds, and ripen their fruit in 

 one year, are called), much time is lost by following this mode of propagation ; 

 it is also found that the seed does not always produce the same identical 

 plant ; above all, it is found that none of the double-flowering, and few of the 

 herbaceous-flowering plants, with which our gardens are furnished, ripen their 

 seeds in our climate. This led to other methods of multiplying ; for, besides 

 the roots properly so called, which attach themselves to the soil, and draw 

 from it the principal nourishment of the plant, it is found that each branch 

 conceals under its outward covering a bundle of fibre or tissue, which, imder 

 favom-able cu-cumstances, develops roots, and becomes the basis of an inde- 

 pendent plant, identical with that from which it sprung. Many plants have 

 also a crown with buds or eyes, each capable of propagating its species. 

 Every plant vrith roots of this description may be divided into as many 

 portions as there are eyes, taking care that a few fibres are attached to the 

 root, and each will become an independent plant. The Potato, and all the 

 bulbous and tuberous plants, are familiar examples of this principle of pro- 

 pagation ; so ai-e the Dahlia and Paeony, which grow better when the set is 

 confined to a piece of the tuber with one eye attached, than when planted 

 whole. So conspicuous is this in the Potato, that, where it is planted wlioU, 

 all the eyes except one, or at most two, are scooped out with a sharp knife ; 

 and the only argument on which that mode of planting is adopted at all is 

 that it supphes the young plant with more of its natural pabulum while it is 

 rooting and thus increases the vigour of the young plant. 



CJ55. Other plants throw off short stems, like the Daisy and House-leek, by 

 means of which they are propagated. Others again, like the Strawberry, throw 

 off runners, each of which is furnished with its root-fibre already elaborated, 

 only requiring soil in which to root itself. But there are others, where nature 

 requires the aid of art. Propagation by layos, which consists in arresting 

 the circulation of the sap on its return to the roots, is one of these. In thi* 



