"The best method of increase is that of grafting. A graft or scion,
which is a shoot with two or more buds on it of last year's growth, is
inserted on the stem of another plant called the stock.

"By means of this process of grafting, trees bearing poor fruit are made
to bear good fruit. Wild fruit trees are brought under cultivation, and
a given tree may bear several varieties of its given fruit. For example,
I have in mind a tree, the marvel of my childhood, which bore big sour
apples, beautiful Gravensteins, and a good quality of Baldwins. This
sort of experimenting with trees is not only as good as a puzzle, but is
of great value. To make a wild apple tree with its gnarly, little sour
apples into a really truly, well-behaved tree bearing good fruit is
worth while, is it not? Grafting is not only a method of improvement but
of taming stock, which is after all improvement.

"There are certain necessary precautions to take in this operation of
grafting; for this, like budding, is a surgical operation.

"In all woody branches the outer layer is the bark; next comes the green
layer. Between this layer and the real wood is a mass of fibres which go
by the name of 'cambium'. The cambium layer of the stock and the scion
must be one against the other in grafting in order that the sap may flow
freely as before. This layer of cambium might be likened to our blood
system. The two cambium layers must be pressed closely together so that
the operation may be successful. And finally no cut surface should be
left exposed to the air. It is air, you know, that plays havoc with
flesh wounds. More and more we see that tree doctors have a work
something like our own physicians.