106 
GARDENING AS A SCIENCE. 
Every cutting should be so arranged, as to depth, and fixed firmly in the wet 
sand : others may be inserted to stock the pot, if there be plent)^ but those round 
the rim are most likely to succeed. A bell-glass must finally be placed over the 
cuttings, its edge dipping below the surface, to exclude the air ; or what is prefer- 
able, a double pot, with a bed of sand between both, so as to receive the rim of the 
glass, might be adopted. The heat of a very gentle hotbed, or propagation-house, 
and due attention to equable moisture, will prove the fact of our assertion ; and, 
though slowly, plants will be obtained, which may be safely removed to single pots 
of heath-soil. In this way many plants, that resist the ordinary treatment, might 
be made to produce roots. 
The above is a digression, but not uninstructive, nor irrelevant to the object 
in view, by which we would prove that if the life of any member of a plant, severed, 
or partially severed, by a ring or cut, from its parent, can be preserved intact, sur- 
rounded by a moist medium suitable to its habits, for a time sufficient to permit 
the formation of a ring of consolidated, that is, organized, vital membrane, or 
cambium, at a wounded joint ; that member will produce roots, and become a 
perfect plant. Now, a layer of a woody plant, if it be a free rooter, — as for 
instance the Vine, — will emit roots without any wound, merely by the obstruction 
caused by the flexure of a portion of a shoot made to curve into the ground ; but 
in the case of a shrub which is with difficulty induced to emit roots, a cut is made, 
which ought to pass through a joint, and beyond it, so as to form a tongue, which 
also ought to be cut across just below the joint, so as to sever the rough piece of 
wood attached to it. It is evident, that by this slit and cross cut the com- 
munication with the parent must be interrupted partially, and that the sap from it 
can only pass through the uncut side of the shoot. But the case is different with 
the parts above the wound; these remain entire, if we admit the doctrine of 
a descending current of laborated sap, or of vital organizable matter, that sap in 
passing down will be diverted into two channels, one taking its regular course 
down the sound half of the branch, the other passing to the cut side, and till it 
arrive at the joint which has been cut through and across. Here, then, the half of 
the joint acts as a cutting, a callus first forming, which, after a time, emits, or 
becomes roots that pass into the soil : the layer, therefore, sustains the life of the 
shoot till the phenomena of rooting are effected. Some plants are so brittle, that it 
is found difficult to cut the tongue, and bend the wounded shoot, even an inch 
below the surface : in this case, it would be advisable to ring the shoot, that is, to 
take off a ring of bark T Vth to -J-th of an inch broad, just below a joint, then to break 
out the bottom of a garden pot, pass the shoot cautiously through it, and fill the 
pot with heath-mould, very sandy loam, or sand and leaf-mould, according to the 
nature of the plant : thus we have operated very successfully upon Rhododendron 
of several species ; and the plan is suitable to the varieties of moss-rose. 
In layering carnations and other herbaceous subjects the knife should enter 
between two joints, pass through the upper one, and beyon^l it, taking off the 
