192 THE PROPAGATION OF PLANTS 



The first by layers ; 



The second by scions, or slips ; 



The third by grafts. 



When you intend to multiply by subdivision, you place 

 that portion of the plant which you intend to separate 

 from the remainder under such circumstances as are requi- 

 site to enable it to develope the organs in which it is de- 

 ficient, and which are necessary to its independent exist- 

 ence. If it be a branch, the organ wanting is a root ; 

 if it be a root, the organ necessary to be developed is a 

 stem. How is this to be accomplished. 



Emily. You must, I suppose, bury the extremity of 

 the branch in moist ground, to favor the developement of 

 roots ; and, in the other case, train the roots above ground 

 to encourage that of branches. 



Mrs. B. Exactly. It is the cambium, you must recol- 

 lect, which, in its retrograde course through the liber, and 

 partly through the alburnum, nourishes these germs ; if, 

 therefore, you propose to develope them in any particular 

 part of the plant, you must accumulate the cambium in 

 that spot. This may be done in several different ways. 

 In the first place, you may make an annular incision in 

 the bark or rind, and, by thus impeding the descent of the 

 cambium, accumulate it in the upper section, where it will 

 produce a swelling or protuberance of the bark. The 

 germs situated in the neighborhood of this rich magazine 

 of food, if in other respects favorably circumstanced, are 

 developed ; that is to say, if the annular incision be ex- 

 posed to light and air, the germs of branches will shoot; 

 if below ground, those of roots will strike into the soil. 

 Indeed any casual interference with the descent of the 

 cambium is almost immediately followed by the sprouting 

 of a bud. In order to make a layer, you bend down a pli- 

 ant branch without separating it from the plant, and fasten 

 it in the ground ; sometimes a slight incision is made at 

 the spot in which it is confined. Now, what follows ? 

 The cambium, descending through the branch, finds some 

 difficulty in returning to the stem : this obstacle is suffi- 



1051. What are the different ways of multiplying plants by division'? 

 1052. How is it to be done! 1053. What does Mrs. B. say must 

 be recollected 1 ? 1054. How are germs made to develope themselves'? 

 1055. If the annual incision be above ground what will be the result; 

 and if below ground what will it be! 1056. In order to make a layer 

 what is donef 



