om which the scion is taken, the tree on which it is grafted, and
the time and the manner in which it is done: for the pear cannot
be grafted on an oak, even though it may upon the apple. In this
operation many men who have great faith in the sayings of the
soothsayers give heed to their warning that as many kinds of grafts
there may be on a tree so many bolts of lightning will strike it,
because a bolt of lightning is generated by each graft (_ictu_).[91]

If you graft a cultivated pear upon a wild pear tree no matter how
good it may be, the result will not be as fortunate as if you had
grafted on another cultivated pear. Having regard for the result, on
what ever kind of tree you graft, if it is of exactly the same kind,
as, for instance, apple on apple, you should take care that the scion
comes from a better tree than that on which it is grafted.

_e. A "new" method--inarching_

There is another operation recently suggested,[92] for propagating one
tree from another, when the trees are neighbours. From the tree from
which you wish to take a scion a branch is trained to that on which
you wish to make the graft and the scion is bound upon an incision in
a branch of the stock. The place of contact of both scion and stock is
cut away with a knife so that the bark of one joins evenly with the
bark of the other at the point of exposure to the weather. Care
should be taken that the growing top of the scion is pointed straight
upwards. The following year when the graft has knitted, the scion may
be cut from its parent tree.

_Of when to use these different methods_

XLI. The most important consideration in propagating is, however, the
time at which you do it: thus things which formerly were propagated in
the spring now are propagated in summer, like the fig, whose wood is
not heavy and so craves heat, as a consequence of which quality
figs cannot be grown in cold climates. For the same reason water is
dangerous to a new fig graft because its soft wood rots easily. For
these reasons it is now considered that midsummer is the best season
to propagate figs. On the other hand it is the custom to tie a pot
of water above a graft of hard wood trees so that it may drip on
the graft and prevent the scion from drying up before it has been
incorporated with the stock. Care must be taken that the bark of the
scion is kept intact, and to that end it should be sharpened but so
that the pith (_medulla_) is not exposed. To prevent