144 
GRAFTING-KNIFE. 
bearing-wood duly distributed in every part of the 
trees and properly exposed to the air and light, 
and at the same time, to remove all superfluous 
and useless branches which tend to exhaust and 
cause premature decay. 
The most favorable season for pruning, in gen¬ 
eral, is when the trees ? : m in leaf and their vitality 
is in full action,* for, in ihany instances, as in the 
oak and tvalnut tribes, if performed during the 
dormant periods of the year, an incipient decay of 
the surface of the wound takes place, and the hark 
below loses its vitality, and the wound soon be¬ 
comes enlarged to a considerable extent downward, 
as indicated at «, in Jig. 31 ; and in addition to the 
Fig. 31. Fig. 32. 
Pruning Trees. 
space occupied by the branch, it exposes a portion 
of the surface of the stem to the action of air and 
moisture, which in time decays, and leads to final 
destruction. On the contrary, this rarely occurs 
in a vigorous tree that has been pruned in summer, 
soon after the expansion of the leaves, when the 
vital functions are in full activity, and the layer 
of alburnum or young wood has already begun to 
be formed, and which may be seen around the 
edges of the wound, as shown in fig. 32, by the 
white ring at b. As the season advances, the 
wound becomes more and more covered by the 
young wood, which, by the end of summer, 
will be so far ripened, as to protect the bark from 
the effects of moisture and winter frosts. The 
proper time for performing this operation iswvhen 
the leaves have acquired one half or three fourths 
of their full sizes. There is another advantage, 
also, attending this period for pruning, in enabling 
the operator to free the trees from an excess of 
foliage, and to give proper weight and symmetry 
to their heads. These principles have been de¬ 
duced from experience, and are strictly in accord¬ 
ance with the laws of vegetable physiology. 
There is a prevailing opinion that, if trees be 
pruned whe'n the sap is in free circulation, they 
will “ bleed,” and thereby deprive themselves of a 
portion of their chief food and nourishment. This 
“ bleeding,” as it is termed, can be of no essen¬ 
tial harm to a tree, as nearly two thirds of the sap 
is thrown off by evaporation through the surfaces 
of the leaves, after having performed its most im¬ 
portant functions, while the other third is supposed 
to undergo peculiar changes, and contributes to the 
formation of wood, bark, leaves, fruit, &c. There 
is also a popular notion, that when branches are 
taken from a tree, so many organs of waste are cut 
off; and it has been practically insisted upon, that 
by the excision of large branches, the supply of 
sap and nourishment which went to their support* 
would cause a proportionate increase of stem. 
The results of experience, it may be unnecessary 
to add, prove this opinion to be erroneous in prin¬ 
ciple, and that when a branch is cut off, a portion 
of nourishment to the stem is also cut off from the 
junction downward to the root. Every branch of 
a tree, of whatever size it may be, not only draws 
nourishment and increase of substance from the 
stem and its corresponding root in proportion to its 
size, but also supplies them in return, with a due 
proportion of nutriment, and by which their sub¬ 
stance is increased; for, if an overgrown branch of 
a thrifty tree be pruned off, the annual increment 
of the diameter of the stem is found not to exceed 
its previous rate of growth ; or, the excess, if any, 
is not equal to the amount of wood which had 
been periodically formed by the branch or branches 
thus separated from the stem. If the branch* 
whether large or small, acted merely as a drain on 
the vessels of the stem and root, and if the sap it 
derived from them were elevated to the leaves 
of the branch, and thence returned no farther 
than the origin or point of union with the stem, 
then the common opinion would be correct. On 
the contrary, however, when it is found that the 
existence and increase of every branch, twig, and 
leaf, depends on a communication with the root, 
and that this communication passes through the 
stem downward to that organ, and from it upward 
periodically, and, moreover, that every periodical 
series of new vessels thus formed in the branch, 
has a corresponding series of vessels found in the 
stem from its point of emitting the branch to the 
root, it is clear that a branch not only increases in 
substance by the functions of its own organization, 
but must, of necessity, periodically increase the 
substance or diameter of the trunk or stem. 
D. Jay Browne. 
Read before the New York Farmers' Club , 
April 2, 1844. 
GRAFTING-KNIFE. 
As the present is the season for selecting and 
setting grafts, and knowing the lively interest you 
take in all that pertains to the fruit-garden and or~ 
chard, I send you herewith the description of a 
knife which I have found superior to all others, for 
splitting the head of the stock in performing that 
operation, both as to convenience and expedition. 
Its form will best be seen by a glance at the ac¬ 
companying drawing. 
A Grafting-Knife, Fig. 33. 
It should be made entirely of steel, and its great 
advantage consists in the curved edge b, b, which 
instead of loosening the bark from the stock, and 
thereby rupturing the vessels which convey the 
sap, hugs it to the wood, and makes a clean 
smooth cut. 
It is used by forcing it into the stock with an os* 
