262 Principles of Gardening physiologically considered. 



observed, that most plants which have a rapid and luxuriant 

 vegetation, and whose wood contains much pith, and is therefore 

 not firm, are easily propagated by cuttings ; such, for example, 

 as a great number of our hothouse plants, shrubs, and annuals 

 at certain periods, and many of our soft-leaved greenhouse 

 plants, such as pelargoniums, salvias, petunias, nierembergias, 

 fuchsias, and the different species of calceolarias and verbenas; 

 among which but few have evergreen leaves, such as our com- 

 mon myrtle. Cuttings, on the contrary, of trees and shrubs 

 that have hard wood, and generally with evergreen leaves, and 

 a slow and tardy growth, strike with more difficulty ; such as 

 Banksw, Dryandrar, Acacia, Ardisia, Casuarina, Zaurus, Camel- 

 lz'tfjPinus, Scottza, and the different speciesof Quercus, with many 

 others. This is, however, by no means a rule without excep- 

 tion, as in many genera one species grows easily, and another 

 with difficulty ; and there are also many with soft wood which 

 easily rot on the surface of the cut, or drop their leaves, &c. 



As soon as the cutting is separated from the parent plant and 

 put into the earth, it begins to receive the crude nourishing sap 

 through the cut (Schnittwunde). As the vessels have been in- 

 jured in making the cut, the nourishing sap no longer ascends 

 by endosmosis in the woody body, but the buds and leaves on 

 the cutting act by the evaporating process (Verdunstungs Pro- 

 gress) somewhat like a pump (as M. Meyen so emphatically ex- 

 presses it), and thus draw the sap upwards to the buds and 

 leaves, where it becomes formation sap, and, returning in the 

 inner bark, comes out at the cut, where it becomes hardened, 

 and forms a parenchymatised cellular tissue, which by degrees 

 frequently covers the whole surface of the cut, and produces the 

 callus formation. 



The callus continues to grow larger and thicker till the buds 

 on the cutting begin to unfold themselves ; and when it has 

 attained a considerable size it supplies the place of roots, as it 

 imbibes the crude nourishing sap and conveys it to the woody 

 body. The developement of the bud produces a transformation 

 in the deposited nourishing sap in the cutting, which is partly 

 used in effecting the developement of the young shoot, and partly 

 in aiding the increased vital action, and is again returned by 

 means of the inner bark. The young callosity is thus formed 

 on the cutting, and also the formation of the root in close con- 

 nexion with it, which always has its rise in the former and 

 proceeds from it. 



The root, therefore, generally comes out at the base of the 

 lowest node on the side of the bud, and when the cut is properly 

 made it comes out immediately above it ; or it comes out in a 

 similar manner from all the nodes which are under the soil, as 

 may be seen in the closely leaved plants, such as E'pacris, 





