[36].
This repetition of our directions on pruning is intentional—“Carthago
est delenda.”
[37].
The coniferæ have a weaker or more connected vitality than
most other trees—the whole individual participating in the injury
of any part. Perhaps this arises from the liability of resinous
juice to putrescency—any putrid affection in one spot of the more
vital part of the tree spreading quickly
over the whole.
[38].
Transplanting having an opposite influence on the young
of herbaceous and woody vegetables, in the former when
not already rising into stem, retarding, and the latter
accelerating or furthering development of the reproductory
parts, is a good lesson to reasoners from analogy. The
root-fractured herbaceous plants repairing the injury almost
immediately, and before the rudiments of the reproductory
parts have time for expansion, the greater quantity of
moist nourishment afforded by the unsought newly stirred
soil, produces a flush of radical leaves, which react to
further the extension of the roots. The new rootlets have
again more connexion to promote the growth of the radical
leaves, and to induce offsets—tillering—from the sides
of the bulb, than to nourish or mature the core part, from
whence the stem arises—a certain comparative extension and
maturity of the core being necessary to the rising of the
stem. Thence seeding can be retarded, and life in annuals be
continued, ad libitum. On the contrary, in woody vegetables
of perennial stem, the reparation of the root-injury takes
place slowly, and the evaporation from the stem and elevated
branches and leaves exhausting the little moisture afforded
by the inadequate root-suction during an entire season, gives
time and bias for the germs to pass into reproductory instead
of productory organs even the first season.
[40].
They say a better management has lately been established.
This may be followed for a short time in the high stream of the
agitation, or while the present heads of management remain in
power; but the system, we fear, contains the seeds of evil, which,
like the weeds, will soon overwhelm
the alien good.
[41].
The inferior growth of the part of a hedge which was pruned
before the vegetation had begun, may be ascribed to the vital action
having been checked at the commencement by the destruction
of the buds necessary to stimulate this action; and being deprived
of this first strong impulse, life had remained languid
throughout the season, the roots never recovering their proper
suction or foraging power;—when the pruning was later, a sufficient
stimulus had already been given.
[43].
The want of the annual layers of cellular tissue of wood,
exterior to and separating the annual lineal tubes, is so complete
in some cases of slow growth, that the timber seems only a
light congeries of tubes, without arrangement; hence the age of
the tree cannot be determined but by a section of the root-bulb,
where the growths are larger, and
the deposits regular.
[44]. The climate of a country in regard to annual
steadiness, can be pretty accurately determined by the
appearance of the annual layers of trees, especially of the
pine tribe; and in a new settlement where great difference of
size of layer, and of resinous deposit is observed, we may
be pretty certain the seasons are not steady, or that insect
depredations or blights occur; and a reserve of food ought
always to be retained. By careful inspection of the nature
of the annual wood deposit, or of the locality with regard
to moisture, it may be ascertained, whether the irregularity
has been owing to difference of temperature, or of moisture.
In warm climates the irregularity will generally depend
on drought and moisture, and in cold climates on heat and
cold; though sometimes the depredations of insects, such as
locusts, or of blights, may be the cause.
[45].
Though we give this experiment, we admit that little dependence
can be placed upon a single fact. The trees must have
been different in variety, and probably in sex, both of which may
occasion a discrepancy.
[46].
The time the weight is in suspension, must be attended to. A
beam will support a much greater weight during a minute than
during an hour; and two beams may be found, the one capable
of supporting the greatest weight during a minute, and the
other the greatest during an hour.
[47].
We shall not here introduce the interminable discussion of
dry-rot, as it remains to be proved that moderately fast grown
young timber is at all more liable to dry-rot than small-growthed
old, provided the sap-wood be entirely removed.
[48].
In fairness, it may be proper to explain, that the greater
part of the trees we have thus cultivated have been of
Pyrus, although we commenced the practice with common
forest trees—yet the pear and apple vary nothing from the
oak and ash in the primary stage of life, in as far as
respects the extension—we can also profit fully as much by
raising apple timber of proper fast grown variety, as by any
other timber; and have it in our power to sell this timber to
machine-makers at double the price of oak of the same size.
[49].
We think Sir Henry would find some of the failures of which
he owns he cannot well ascertain the cause, but occurring especially
in beech and oak, to be owing to a number of the lower
roots, which are by far the tenderest, being bruised by the weight
of the tree itself, when he turns it repeatedly over from the one
side to the other, in order, by throwing in earth beneath it, to
raise the root on a level with the surface of the field, the whole
weight of the incumbent mass resting upon these soft roots. The
oak, and still more the beech, are exceedingly susceptible to injury
from cutting or bruises, and die far inward from the laceration.
The wounded lower roots, especially when any vacuity is
left not filled close in with earth, where mouldiness might generate
in a dry situation, or when soaking in moisture for a part of
the season, will become corrupted; the putrefaction thence gradually
extending upward into the bulb, will contaminate the whole,
and the second or third year after planting, the tree
will be dead.
[50].
We understand freezing the earth around the bulb is an old
practice.
[51].
We particularize the oak, cork-tree of arid warm Spain, and
much of the timber of New Holland. Owing to the hot parching
air in the latter place, the epidermis becomes dried to such a
degree, that contracting by the drought, and bursting by the
swelling of the enveloped stem, it peels off like the old skin of a
serpent, and is often seen hanging upon the tree in large shreds
like tattered garments. In several kinds of trees, we have counted
regular annual rings of desiccated bark; in some kinds this appeared
a growth or deposition, in others, mere parched exuviæ.
Trees attain some age before the exuviæ commence; the deposit
begins the first season, even in sheltered situations. The cork-tree,
and the small-leaved elm, shew the greatest annual deposit of
dry bark. The former does, and the latter is said to belong to
warm arid countries; both form a better nonconductor of heat
than any other dry bark we are acquainted with—infinitely better
than the bark exuviæ of trees which approach
the polar regions.
[52].
We do not pretend to explain how it is, that one kind of
climbing plant follows the sun in its convolutions, and another
traverses his course. There surely cannot be any thing in a habit
acquired in the southern hemisphere.
[53].
In proceeding further on in Sir Henry’s volume, we have
noticed an excellent observation quoted from Du Hamel: “The
extension of the shoot is inversely as its induration, rapid while it
remains herbaceous, but slow as it is converted into wood. Hence
moisture and shade are the circumstances, of all others, the most
favourable to elongation, because they prevent induration or retard
it.” Although quoting this, Sir Henry recurs to his old opinions,
and proceeds to observe, “Trees so circumstanced, push
upward to the light; and from the warmth which their situation
affords, their stems being thin and slender in proportion to their
height, they are destitute of strength to
resist the winds.”
[54].
We do not mention temperature, because we are not in possession
of facts sufficient to lead us to form an opinion on the
subject. Judging from animal analogy, of which our author is so
fond, we notice, that those animals exposed in open atmosphere,
have generally warmer blood than those who lurk in holes,—even
than those of the same species who happen to live under shelter.
Now evaporation takes place from animals as well as from vegetables,
and the consequent cold is more than balanced by the heat of
what may be termed the vital fire, which, like most other fires,
burns brightest on exposure to a current of atmospheric air, being
increased either by the result of the new chemical combinations
having less capacity for heat, or by the stimulus of the fresh
moving air exciting the vital action. Of the general influence of
close forest on temperature, we are also not very well assured;
but the few facts which observation has afforded, lead to the
opinion, that to the northward of 50 deg. Lat. forests have higher
temperature than bare country; that from about 50 to 30 degrees
Lat. forests are cooler in winter and
warmer in summer;
and that nearer the equator, forests are generally cooler
than bare country. But the temperature is regulated so much
by the position of seas and lakes, in combination with the prevailing
currents and strength of currents of the air—by the configuration
of the country,—moisture and cloudiness of the atmosphere
and quantity of rain,—by the composition, arrangement, and colour
of the soil,—by the lower vegetable cover, and even by the
nature of the forest itself, whether deciduous or evergreen, that
particular facts must be very carefully weighed to enable us to
reach general conclusions. It is generally understood, that forests
render the climate moister.
[55].
Our experiments have not yet been carried so far, as to determine
if, by any arrangement of drying or exposure, they may
be seasoned to sustain intense frost, which may affect them
differently from moderate frost, either by causing complete congelation
of all their structure (moderate freezing appearing only
to congeal their fluids, but not entirely the containing vessel, at
least only partly congealing the mass), or by killing the vital
principle itself through nervous affection. The potatoes became
green from the exposure to the light, and we rather think acquired
greater hardihood of constitution, or greater vitality or excitability
by the exposure, thence greater power to resist the cold,
independent of the disposition they acquired by desiccation to endure
it.
[56].
Is the rending of the stems of trees, during intense frost, internal
only, and occasioned by the alburnum expanding more by
congelation than the drier mature wood? or, is it external, and
caused by the contractile effect of the dry air and cold on the alburnum
rendering it insufficient to surround the mature wood,
which, from dryness and want of living susceptibility, may not
contract so much.
[57].
The fineness of vessel or fibre of the Siberian crab, may be
induced by the arid warm air, the continued radiation of heat and
light upon the portion above ground, and the coldness of the ground
around the roots during the short summer in Siberia, where the
air and surface of the ground is warm, and vegetation progressive,
while the ground remains frozen at a small depth. Like all varieties
of plants habituated to colder climate, the Siberian crab
developes its leaves under less heat than varieties of the same kind
which have been habituated to milder climate.
[58].
We have not taken Sir Henry in the literal sense. Timber
is well known to decay sooner in a warm than in a cold country,
cæteris paribus.
[60].
The preliminary sentence is very vaguely worded; we suppose,
“increasing the annual circles,” means increasing them in
thickness, not general contents of length multiplied by thickness.
But even in the latter sense, we hold pruning tends generally to
diminish the annual circles.
[61].
It is a theory of Mr Sheriff, Mungo’s Wells, that all plants
have excrementitious deposit from the roots, the deposit from one
kind affording a good manure to another kind. Thence the advantage
of mixed grasses and legumes in pastures, and of the
rotation of different
kinds of crops.
[62].
Vegetable soil is sometimes buried deep under volcanic mud,
sand, and ashes, or mixed with the subsoil by earthquakes. In some
districts of South America, the country, from being fertile, has
been recently reduced to sterility, by the vegetable mould being
so much scattered through the subsoil by repeated upheavings and
tossings about by earthquakes, as to be out of the
reach of plants.
[63].
There is a deposition from the atmosphere of saline matter
going on at the surface of the earth, either evaporated from the
ocean, and falling with the rain and dews, or formed by gaseous
combinations—most probably both. In countries where the quantity
of rain is insufficient to wash this saline accumulation away
into the ocean as fast as it is formed, it increases to
such a degree
as almost to prevent vegetation, only a few of what are termed
saline plants appearing. This saline accumulation in warm dry
countries, bears considerable analogy to tannin deposit in cold
countries.
[64].
The matured timber of the larch, in some cases, remains for
a considerable time stained before the rot proceeds rapidly; in
other cases, the rot makes quick progress; in this rapid decomposition,
certain kinds of fungi assist greatly. When once seated,
they seem to form a putrid atmosphere or tainted circle around
them, either by their living exhalations, or corrupt emanations when
dead, which is poisonous to the less vital parts of superior life, and
also expedites the commencement of decay in sound dead organic
matter, such as timber, thus furthering the decomposition so
far as to render it suitable food for their foul appetite, and paving
the way to their further progress.
How their seeds enter into the heart of a growing tree having
no external rottenness, is not very obvious, unless they are inhaled
or imbibed by the root tendrils: from the resemblance which
the growth of some of them has to fermentation, it is not even
very improbable that the animalcules of supposed molecular or
inferior life, have, of themselves, a disposition to unite into some
of these aggregates without the presence of any disposing germ.
The modifications of material attractions, by the varied germs of
superior life—the fixity of some of these deposites after life is gone—the
resolution of these into inferior animalcular,
or even molecular,
life—and the instrumentality of zoophytes of the lower order of
organization, in hastening this decomposition by the balancing of
the attractions of this secondary life, afford a wide field for investigation.
Those uncouth sportings of nature quickly appear and
disappear as material spectres, feeding on corruption, and mocking
at primary life.
[65].
We have raised crops among young trees (as well timber as
fruit trees), not four yards apart, by plough culture, and have found
the process, after the ploughmen and horses were accustomed to it,
not much more expensive than common cultivation, and the crop,
till the trees became too close, scarcely inferior. By means of a
long muzzle to the plough standing out towards the left side, and
a driver to the horses beside the ploughman, we succeeded in getting
the two first furrows lapped a little over each other in the row
of trees, where the gathering of the ridge commenced (we gathered
up at every other row). In the row of trees where the finishing
of the ploughing of the ridge occurred, we were obliged to leave a
stripe of ground about two feet wide, to be dug by the spade. The
horses required to be yoked in file, and to drag by ropes (traces)
rather than by chains, as the bark of the trees was liable to be
rubbed off by the latter. The more to guard against rubbing, we
had the swingletree constructed so that the trace-ropes came out
from a hole in the ends, without any hook. In harrowing the
ground, one man is required to lead the horses, and another to direct
the harrows. In rich soil, under cultivation of green crop, in
this manner, trees progress very rapidly, and from the open arrangement
acquire very healthy constitutions.
Of course, when
not coniferæ, the plants require a little more attention to train to
one leader and equality of feeders, than when close planted. We
should consider plough cultivation of young woods, provided
ploughmen as expert and careful as the Scots could be obtained,
much more worthy the attention of the English planter than the
Withers’ system (trenching). Need we mention, that in green crop,
every thing depends upon plenty of manure and of well-timed
plough and horse hoe labour? Excepting in the case of larch, we
should dread no injury to the trees or timber from
plenty of manure.
[66].
We are indebted to our friend Mr Gorrie, Annat Garden, for
the fact, that English acorns throw up a much more luxuriant
stem than the Scots; they forming a step of several inches
when planted next each other in the nursery line. We should
consider this to arise from the largeness of the rudiments of
the plant, and greater quantity of garnered nourishment in
the English acorns, which are nearly double the size of the
Scots, our present climate being insufficient for the proper
development. This leads to the question, will the greater
luxuriance balance any tenderness from want of acclimatizing?
Would the oak keep its present locality in Scotland if left
to nature? A careful inspection of the most elevated peat
mosses in which remains of timber exist, and a comparison of
the size of the seeds found there, with that of those of the
present day, grown the nearest to this in situation, would
resolve the question of refrigeration.