o reduce the dimensions of a plant
when getting too large for the house in which it is growing. By
gradually inducing the production of new roots from the central or upper
portions of the stem, it becomes possible, after a time, to sever the
connection between the original roots and the upper portion of the
trunk, and thus secure a shortened plant.

On the subject of adventitious roots, &c., reference may be
made to Trecul, 'Ann. Sc. Nat.,' 1846, t. v, p. 340, et vi, p.
303. Duchartre, 'Elements de Botanique,' p. 219. Lindley,
'Theory and Practice of Horticulture.' Thomson's 'Gardener's
Assistant,' pp. 374, _et seq._; and any of the ordinary
botanical text-books.

=Formation of adventitious buds on roots.=--One of the characteristics
by which roots are distinguished from stems in a general way consists in
the absence of buds; but, as is well known, they may be formed on the
roots under certain circumstances, and in certain plants, e.g., _Pyrus
Japonica_, _Anemone Japonica_, &c. What are termed suckers, owe their
origin to buds formed in this situation.

If roots be exposed or injured, they will frequently emit buds. The
well-known experiment of Duhamel, in which a willow was placed with the
branches in the soil and the roots in the air, and emitted new buds from
the latter and new roots from the former, depended on this production of
adventitious organs of either kind.

Gardeners often avail themselves of the power that the roots have of
producing buds to propagate plants by cuttings of the roots, but in many
of these cases the organ "parted" or cut is really an underground stem
and not a true root.

M. Claas Mulder has figured and described a case in the turnip-radish of
the unusual formation of a leafy shoot from the root, apparently after
injury.[150] From the figure it appears as if the lower portion of the
root had been split almost to the extremity, while the upper portion
seems to have a central cavity passing through it. From the angle,
formed by the split segments below, proceeds a tuft of leaves, some of
which appear to have traversed the central cavity and to have emerged
from the summit, mingling with the other leaves in that situation. The
production of a flower-bud has even been noticed on the root of a
species of _Impatiens_.

=Formation of shoots beneath the cotyledons.=--The tigellar or axial
portion of the embryo plant, as contrasted with the radicle proper, is
ver