THE CULTIVATOR. 
177 
collected in the preceding summer; while, from this 
cause, new root fibres shoot out towards the end of 
winter. These, having all the freshness and activity 
of youth, display their energy by pumping up the 
moisture from the soil. The awakening of vegetation 
then arises from two causes,—the activity of the new 
root fibres which push the sap they have taken in on¬ 
wards from behind ; and the activity of the bark which 
draws it upwards. When it arrives at the leaf-buds 
it causes them to expand ; but acts first on those at 
the summit of the branches, either because it can rise 
more easily in a perpendicular direction, or rather be¬ 
cause the wood and bark of the upper branches is 
younger, and therefore more energetic.” 
That these are not the only causes, it is proved by 
plants often expanding their buds in spring, when the 
cold is greater than in autumn, and bulbs and the tu¬ 
bers of the potato cannot be kept from shooting ex¬ 
cept in considerable cold. It may therefore be infer¬ 
red that plants are endowed with, or acquire periodi¬ 
cal tendencies, in the same way as we ourselves go 
to sleep and waken again at the periods to which we 
have become accustomed. This is farther proved by 
plants taken to climates differing from those where 
they have been produced. English apple trees, for 
example, when first taken to Canada, bloomed much 
too early, and had all their blossoms nipt with the 
spring frosts, till, after being inured to the climate 
they learned to bloom later; which our almond trees 
in England, brought from the warm banks ol the Jor¬ 
dan, have never yet sufficiently learned, and hence 
those fine trees, whose spring blossoms are so delight¬ 
ful, are rarely fruitful. 
Bulbs become torpid about the close of spring, and 
re-awaken into life in the autumn, continuing to grow 
during the winter. 
It is worth remarking, that when the buds of a 
plant have been once awakened into expansion, and 
new root fibres have begun to form, they will go on 
even at a lower heat than would have served to rouse 
them at first, as was experimentally proved by Mir- 
bel and Chevreul. 
It is evident from the preceding facts and inferen¬ 
ces, that the strength which a plant will show in 
the spring, and consequently its successful growth in 
the succeeding summer, will depend much on the 
store of nutrient matter which it has been able to pre¬ 
pare and store up, in the buds, the pulp-wood, the 
root, and more particularly in the crown of the root; 
an important consideration in pruning and forcing, as 
well as in most of the processes of gardening. 
The Offices of Roots and Leaves. 
[From Madden's Chemical Reports .] 
Plants may be said to consist of two great parts, 
the root and the stem, with their various appendages. 
But since we are in this place merely to consider one 
function of vegetable life, namely, the function of ab¬ 
sorption, or the manner in which plants bring matter, 
external to themselves, within the range of their vital 
actions, we may confine our researches almost entire¬ 
ly to the roots and leaves, —these being beyond doubt, 
the parts by which extraneous matter is first received 
into the plant; and, in the first place, let us examine 
the functions of the root. 
The term root is generally considered to include all 
that part of the plant which is beneath the surface of 
the soil. This, however, is not strictly correct; for 
many plants possess what botanists call a rhizoma, or 
underground stem. The true root is that part of the 
plant which, from the instant of its bursting the co¬ 
verings of the seed, begins to direct its course down¬ 
wards (or towards the earth’s axis,) “with a tenden¬ 
cy so powerful, that no known force is sufficient to 
overcome it.” Moreover, it differs from the stem in 
many of its characters ; thus, it does not divide itself 
into smaller fibres in the regular manner, in which 
stems generally give off their branches. Again, it 
never produces leaves or scales ; and another import¬ 
ant distinction is, “ that it never becomes green (at 
least in tissue) when exposed to the action of air and 
light, while all the other parts of vegetables, when 
thus exposed, assume that colour.” The root is di¬ 
vided into the body and fibres, the latter of which will 
alone claim our attention. These fibres are furnish¬ 
ed at their extremities with a remarkable structure, 
which, trom its resemblance to a sponge, has been 
termed spongiole. It consists of an extremely loose 
texture, and is most probably merely “ the newly 
formed” internal “tissue” of the root itself, deprived 
of its more dense covering, or cuticle, as it is termed. 
This opinion is very much strengthened by the well- 
established fact, that roots grow by their extremities 
only. In this manner the spongiole is always being 
renewed ; and, what is of still more consequence, is 
never long m one place. On this account it is that 
plants which live many years (if not growing too near 
others of the same kind) are not liable to die from 
having exhausted the soil; or, in other words, are 
not liable to be starved to death ; for it is evident that, 
by the constant change of position of the spongiole, 
which is the only part of the root by which nourish¬ 
ment is received into the plant, there must be a con¬ 
stant supply of food, so long as the soil around it con¬ 
tains any organic matter in a fit state for absorption. 
It has been shown, by innumerable experiments, that 
the spongioles, or absorbent extremities of the roots, 
cannot take up any thing but fluids ; or, at all events, 
if they can absorb solids, they must be in such a mi¬ 
nute state of division, that they would remain sus¬ 
pended in water, even for a considerable time, which 
is a fineness of particles far greater than will proba¬ 
bly ever be attained by any mechanical means. 
It has likewise been proved, that plants are capa¬ 
ble of choosing to a certain degree, their food; or, in 
other words, of selecting those substances which are 
best adapted for their peculiar nature, and rejecting 
what would be injurious. This power, however, ap¬ 
pears to be limited, as it is perfectly possible to de¬ 
stroy a plant by giving it poison by the roots. The 
root, moreover, has the power of excretion, or return¬ 
ing to the earth such matters as are either useless or 
injurious. From this last property of roots, we may 
draw two valuable conclusions; first, That in order 
to poison a plant, the substance used must be capa¬ 
ble of acting rapidly, or it will most probably be re¬ 
jected before it has had time to produce its effect; 
and secondly, that since plants reject substances use¬ 
less and injurious to them, the soil where they grow 
may in time become so impregnated with such substan¬ 
ces as to render it incapable of supporting the same 
species of plant any longer ; or at least until such time 
as the rejected matter shall have been decomposed. 
This point will be enlarged upon when we come to 
treat of the rotation of crops. The next purpose 
which the roots of all land, and the majority of aqua¬ 
tic plants, serve, is obviously to fix it firmly in its 
place. On this account, we find, in many cases, that 
a certain proportion exists between the size of the 
stem and the root. This, however, is subject to 
exceptions. But, on the other hand, in all cases 
an obvious relation may be perceived between the 
form of the root and the kind of soil in which the 
plant grows. Thus, if two specimens of the same 
plant—some of the grasses, for example—be found 
growing, the one in clayey, the other in a sandy soil, 
it will be seen, on examination, that the root of the 
one growing in the sand is much more minutely sub¬ 
divided, and contains many more small fibres, than 
the one which grew in clay ; and the reason of this is 
obvious : We have already seen that the spongioles 
are the only absorbent parts of the root; that they 
exist only at the extremites of the smallest fibres; 
and, moreover, that they can take up nothing but 
what is presented to them in the form of solution.— 
Now, in the clayey soil, from its retentive nature, the 
soluble parts are not allowed to drain away; and 
hence the plant is supplied with food near at hand, 
and, consequently, a few short fibres are sufficient. 
On the other hand, plants growing in sand are fre¬ 
quently deprived of all fluid near them, by the sinking 
of the soluble matters through the loosely aggregated 
soil; in which case the plant would inevitably perish 
from starvation, were it not for the wise law of Na¬ 
ture, which provides against such calamities, by en¬ 
dowing the roots of plants, placed under such circum¬ 
stances, with the power of shooting forth innumera¬ 
ble minute fibres in all directions, in order that ad¬ 
vantage may be taken of every drop of moisture which 
falls in their neighborhood. Nor is it merely in the 
number of minute fibres that the roots of plants grow¬ 
ing in sand differ from those which inhabit the stiffer 
soils. The form of the body of the root is distinct; 
thus, nearly all bulbous, and other large succulent 
roots—as the turnip, for example—require sandy soil; 
and moreover, some plants—as that species of grass 
named Phleum pratense, (meadow cat’s tail, or timo¬ 
thy-grass)—change the form of the root, according to 
the soil they inhabit; thus, in stiff clays, the plant 
just mentioned has a fibrous root, whereas in sand it 
becomes bulbous, and assumes all the characters of 
Phleum nodosum. The explanation here is as evi¬ 
dent as in the former case. The bulbs of the roots 
act as reservoirs of food for the plant; thus, in very 
dry seasons, these bulbs shrivel up, their fluids being 
all needed by the rest of the plant and hence with¬ 
drawn. So beautifully do we perceive in this, as in 
all other cases, that design and adaptation of means 
to specific purposes, which must impress even the 
most sceptical with the absolute existence of a Great 
First Cause. So much for the root and its functions. 
Important and complicated as these may appear, 
the leaf performs offices of a much more obscure na¬ 
ture. In the words of the justly celebrated Bindley, 
“Leaves are at once organs and respiration, digestion, 
and nutrition. They elaborate the crude sap impel¬ 
led into them from the stem, parting with its water, ad¬ 
ding to it carbon, and exposing the whole to the action 
of air.” To describe full} in this place these nume¬ 
rous operations, would not only occupy far too much 
space, but would, to a certain degree, be foreign to 
our subject, as all we wish to examine at present is, 
how the nutritious matter gets into the plant, putting 
completely out of the sight the question as to what 
becomes of it after it is absorbed. From the sentence 
above quoted, we find that carbon is added to the sap 
by the leaves. By this is not meant, however, that 
it is without that substance until it reaches these or¬ 
gans, but merely that an extra quantity of this ele¬ 
ment is hereby added to it. How, therefore, is this 
accomplished] We have already repeatedly stated, 
that carbon always exists in the atmosphere in the 
form of carbonic acid gas. Now, it has been ascer¬ 
tained that the leaves, while exposed during the day 
to the sun’s rays, have the power of absorbing this 
carbonic acid, and afterwards decomposing it, the car¬ 
bon being retained, and the oxygen given out again in 
the form of gas. During the night, however, or in 
the shade, no such change takes place. Carbonic 
acid, indeed, may be absorbed, probably in the form 
of a solution in water, as it is well ascertained that 
leaves take up moisture during the night; but it does 
not appear to undergo any decomposition : part of it, 
in fact, is given out in an undecomposed state; and 
as oxygen is removed from the air, at the same time 
that this evolution of gas is going on, it is supposed 
that plants have the power during the night, of ab¬ 
sorbing oxygen, which dissolves part of their carbon, 
and re-escapes in the form of carbonic acid. Thus, 
we see that, during the night, the exact reverse is 
taking place to what was effected while the leaves 
were exposed to the rays of the sun. In the latter 
case, carbonic acid being absorbed, the carbon is re¬ 
tained, and the oxygen evolved; whereas in the for¬ 
mer oxygen is absorbed, and carbonic acid given out. 
What is the ultimate effect of these complicated and 
apparently inconsistent changes, it is hard to say.— 
The fact, however, remains unalterable ; and from it 
we may draw at least two very valuable conclusions : 
First, From what we have said with reference to the 
formation of carbonic acid gas during the burning of 
vegetable matter, and since it is well known to all 
that this gas is likewise contained in great abundance 
in the breath of all animals, it is clear that, unless 
there were some process in constant operation of re¬ 
moving it from the air, our atmosphere would soon 
become so contaminated with this noxious gas (choke- 
damp,) that it would be incapable of supporting life. 
Now, it has been conjectured that this constant ab¬ 
sorption of carbonic acid by plants during the day, and 
the evolution of oxygen (the constituent of air most 
essential to life.) has the effect of preserving the 
healthy condition of the atmosphere. Secondly —But, 
on the other hand, it is equally important to remem¬ 
ber that the reverse takes place during night; plants 
at that period vitiating the air; which accounts for 
it not being healthy to sleep in apartments where a 
great number of plants are growing. But to return 
from this digression. From the facts above stated, 
we find that the leaves absorb carbonic acid and wa¬ 
ter; and, for the present, we shall rest content with 
this, and proceed at once to consider of what the food 
of plants really consists,—now that we are so far ac¬ 
quainted with that important function exercised by 
plants—namely, absorption—by means of which they 
Receive their nourishment. And, in the first place, 
we may very briefly show the analogy which exists 
in this particular between plants and animals ; by do¬ 
ing which we shall be enabled to render the sequel 
much more intelligible. It is welt known to all who 
are conversant with the functions of living animals, 
that after the food is received into the stomach it un¬ 
dergoes certain changes ; one of the most important 
of which is its being rendered soluble, and afterwards 
is absorbed by a special set of vessels called lacteals, 
and is then carried to the lungs to be converted into 
blood. Now, the analogy is perfect, if we take into 
consideration that plants have no stomach, and, there¬ 
fore all the preparation which takes place in the sto¬ 
mach of animals, has to be performed in the soil. 
Hence Greisenthwaite, a most ingenious writer on 
this subject, says, “ The soil may be regarded as the 
stomach, the common receptacle of the food of plants, 
in which manure is coverted into substances that are 
soluble ; and afterwards those soluble substances are 
absorbed by the capillary tendrils of the roots, in a 
manner exactly similar to that already observed of 
the lacteals of animals.” A moment’s reflection will 
at once, therefore, clear up all difficulties ; for we per¬ 
ceive that the spongioles of the root act exactly as the 
lacteals of animals,—namely, they absorb the soluble 
matters prepared in the stomaeh (soil,) and carry it 
to the leaves to be converted into perfect sap, which 
process likewise corresponds exactly to the conver¬ 
sion of the matter absorbed by the lacteals into per¬ 
fect blood. 
Description of a Grass Seed-Sowing Machine. 
By Mr. Dudgeon, Broomhouse, East-Lothian. 
[From the Edinburgh Quarterly Journal of Agriculture.] 
This machine, of which a model was lodged by Mr. 
Dudgeon about twelve months ago in the Society’s 
Museum, is an amplification of the common broad- 
