SCIENTIFIC PRINCIPLES OF GARDENING. 
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ingly common, for the purpose of continuing esteemed varieties of fruits and flowers, 
accidentally produced by cultivation; as well as for forwarding the fruiting of young 
trees, since seedlings require years to arrive at the bearing state. On examining 
the joining of a graft about a fortnight after it has been made, I have found, as 
in a healing finger cut, a number of small roundish grains, in form of a thin layer, 
produced from the thickening of the pulp, and destined to form the hard substance, 
which in general projects a little externally, and the scar differs in appearance 
from the other parts of the bark. It is however only in the space between the pulp- 
wood and the bark that the uniting substance is formed, and, therefore it is evident 
the slip to be grafted must have this part applied to the same part of the stock, and, 
if these differ in thickness, at least on one side. Nothing can be more erroneous than 
the doctrine, that the buds of the graft send woody matter downwards, which 
passes through the cellular substance into the stock, and covers the wood of the 
stock with new wood ; for every gardener knows that the graft never changes the 
wood of the stock ; this is beautifully shown in the following figures after M. Turpin. 
Fig. 1. a, a black heart cherry 
tree, naturally of soft texture, and 
of large diameter, grafted on a bird 
cherry, naturally hard, and of 
small diameter, c the scar much 
bulged, from the pulp being inter- 
rupted in its descent, d, a paper 
birch, with a smooth bark, grafted 
on the white birch, e, with rough 
thick bark, f, the scar where there 
is no bulging, because the descent 
of the pulp is not interrupted. 
One of the most obvious prin- 
ciples of this process is, that the 
sorts to be grafted should be alike, or nearly alike, because in that case, the arrange- 
ment of the sap and pulp vessels being similar their cut ends will more readily apply 
mouth to mouth, and less obstruction or interruption of the circulating juices will 
take place. The ash may however be grafted on the olive. 
Fig. 2. a, the Pavia lutea, a 
shrub, which never attains the size 
of a tree, cleft-grafted on the horse- 
chestnut, b, a tree of great size. 
It is remarkable that the Pavia is 
much enlarged near the junction 
c, like a tree near the ground, a 
circumstance which would not 
have occurred but for the graft ; 
the bark of which remains distinct. 
d, the white lime-tree grafted on 
the European lime tree, e ; each growing in diameter according to its particular 
