tree even if it
be, as in the giant Redwoods, thousands of years.

Besides forming the regular wood of the tree the cambium also grows out
over cut places and builds in woody tissues that heal over the wounds.
It is owing to this fact alone that budding and grafting are possible.
The callus on cuttings and root grafts is another evidence of the same
phenomenon, for the cambium of the roots of a tree is continuous and
identical with that of the branches.

_The Stock._

The whole practice of successful grafting and budding is the proper
handling of active cambium. The cambium is the cementing material that
unites stock and scion and unless there is active cambium there will be
no union. It must be said here that no matter how great the future
growth of the union, the scion never becomes truly united or fused with
the stock. The cambium grows all over and around the cut parts and
cements them together, but if the graft union be split open fifty years
later, the dead wood of the original scion may be found of the original
size and in the original position. Since, then, successful grafting
depends on the union of the cambium of the stock with that of the scion,
theoretically the best time for grafting and budding would be when the
cambium is most active. Actual nursery practice shows that this is
practically correct, at least as regards the stock.

The ideal stock for propagation purposes is the young seedling of one or
two years growth. In such a stock all the tissues are new and fresh and
working to their maximum capacity and the cambium is in its most active
condition. In top-working old trees it will be found that though the
branches may appear vigorous, they are a long way from having anything
like the active circulation found in small seedlings. Buds put in these
branches would give a very small "live," while the same care on nursery
seedlings could be counted on giving a high percentage of living buds.
In top-working, therefore, it is found necessary in order to get the
cambium sufficiently active, to stub back the branches to mere pollards.
This cutting back should be done in the winter or dormant season. The
following growing season will see a dense growth of very vigorous shoots
trying to repair the injury. See Figure 1. These shoots are ideal stocks
for, on account of their having all the sap from the greater root of the
mature tree, the cambium will be even more active than in the nursery
seedling. Often when