1886. J CHAPTERS ON PROPAGATING. 747 



it may be remarked here tliat there are many curious evidences of 

 imperfect possession of this latent vital force, which are, to say the 

 least, puzzling. It is an easy matter, for instance, to induce the 

 leaf of a cucumLer to emit roots and live for a time, perhaps as 

 long as the average duration of the life of the parent plant, which 

 is annual. But it is impossible to induce it to send forth a stem ; 

 it is imperfect in this respect, that, while it can develop the 

 descending axis or the roots, it does not possess the power to 

 produce the ascending axis or stem, and consequently no plant in 

 the complete sense can result from the process. In the genus 

 Begonia, and many others, on the other hand, the leaves may be 

 chopped up into small bits, each of which has the power, under 

 favourable conditions, of establishing itself as a perfect plant. But 

 this power of reproduction from the leaves alone is given only to 

 comparatively few classes of plants, and such as have it are outside 

 the line of tlie forester's walk in general. The more woody and 

 .arborescent the plant may be, it is generally found that the process 

 of reproduction by cuttings becomes more diflBcult. In a general 

 way, also, the more dense and hard the texture of the wood of any 

 subject is, the difficulty is correspondingly increased. 



The first process that takes place after a cutting is made and 

 planted is the formation of a callus, or a ring of granular matter at 

 its base. Without this there can be no production of root fibres.' 

 This callus is elaborated from the true sap, that which is descending 

 from the upper extremities, and is charged with matter in the right 

 chemical condition to repair waste, heal wounds, and add to the 

 structure of the plant. It cnnnot be formed by the sap in flow, 

 that is, the ascending sap. Yet this idea is conveyed by many who 

 write and have written on the subject, especially in giving directions 

 respecting the proper time to select and make cuttings. The crude 

 sap drawn direct from the soil cannot of itself contribute to the 

 formation of roots or any other organ, till it is chemically changed 

 by the action of the constituents of the atmosphere, which change 

 takes place chiefly in the leaves, but also more or less in every 

 herbaceous part of the plant. It is only at or near the end of the 

 season of growtli that this process of elaboration is perfected ; and 

 it is only therefore then in a general wa}' — with regard to woody 

 or hard-wooded plants — that the work of propagation by cuttings 

 may properly be engaged in ; but the sooner thereafter they are 

 made and planted, the greater are the chances of success. This 

 consideration is of the utmost importance, and it applies more 

 generally and with greater force to deciduous than to evergreen 

 trees and shrubs. Many of the latter class may indeed be propa- 

 gated from ver}^ immature or partially ripened cuttings, if they are 



