THE CULTIVATOR. 
114 
zontal section of the stem ; which also presents a number of lines 
called medullary rays, radiating from the pith to the circumference. 
They are composed chiefly of large cells, extending transversely, 
or in the direction of the diameter of the tree, and composing by 
their union continuous vertical planes the whole length of the 
trunk. 
Every vegetable stem, and also every branch which arises from 
it, is developed from a germ, or bud, which is originally of incon¬ 
ceivable minuteness, and totally imperceptible by any optical means 
of which we have the command. As soon as it becomes visible, 
and its structure can be distinguished, it is found to contain within 
itself the parts which are to arise from it, in miniature, and folded 
up in the smallest possible compass. The portion estined to form 
the stem is gradually expanded both in breadth and height, but 
principally the latter; so that it rises as it grows, during a certain 
period, until the fibres acquire the solidity and strength necessary 
not only for their own support, but also for sustaining the parts 
which are to be farther added. In trees this process generally oc¬ 
cupies one whole season ; during which the growth of the first lay¬ 
er of wood, with its central pith, and its covering of a layer of 
bark, is free and unrestrained. On the second year, a fresh impulse 
being given to vegetation, a new growth commences from the up¬ 
per end of the original stem, as if it were the development of a 
new bud ; and at the same time a layer of cellular tissue is formed 
by the deposition of new materials on the outside of the former 
Wood, and between it and the bark. This is followed by a second 
layer of wood, enveloping the new layer of cellular tissue. 
The effect of this new growth is to compress the new layer of 
wood which had been formed during the first year, and to impede 
its further extension in breadth. But as its fibres, consisting of 
vessels and cells, are not yet consolidated, and admit of still 
greater expansion as long as they are supplied with nourishment, 
their growth, which is restrained latterally, is now directed upwards, 
and there is no farther enlargement of their diameter. From the 
same cause, the pith cannot increase in size ; and is even found to 
diminish by the pressure of the surrounding wood. Thus, the ver¬ 
tical elongation of the entire stem continues during the whole of 
second year, and the trunk becomes sufficiently strengthened by the 
addition of the second layer on its outside to bear this increase of 
its height. 
While this process is going on in the wood, corresponding 
changes take place in the bark, and a new layer is added on its in¬ 
ner surface, or that which is contiguous to the wood. This layer 
constitutes the liber. All these new depositions must of course tend 
to stretch the outer portions of the bark, which had been first 
formed, and which yield to this pressure, to a certain extent; but, 
becoming themselves consolidated by the effects of the same pres¬ 
sure, they acquire increasing rigidity ; and, the same cause continu¬ 
ing to operate, they at length give way, in various places, forming 
those deep cracks, which are observable in the bark of old trees, 
and which give so rugged an appearance to their surface. The 
cuticle has, long before this, peeled off, and has been succeeded by 
the consolidated layers of cortical envelope which form the epider¬ 
mis. But the epidermis, which is continually splitting by the ex¬ 
pansion of the part it encloses, itself soon decays, and is constantly 
succeeded by fresh layers, produced by the same process of consoli¬ 
dation in the subjacent cortical substance. 
During the third and each succeeding year, the same process is 
repeated; new layers of cellular texture and of woody fibres are 
deposited around those of the preceding year’s growth, and a new 
internal coating is given to the liber of the bark. The compres¬ 
sing power continues to be exerted on the internal layers of wood, 
directing their growth vertically, while they are capable of elonga¬ 
tion, and can be supplied with nourishment. In time, however, by 
continual pressure, and accumulating depositions of solid matter, 
the vessels and the cells become less and less pervious to fluids; 
till at length all farther dilation is prevented. But the tree still 
continues to enlarge its trunk by the annual accessions of vigorous 
and expansible alburnum, and to take its station among its kin¬ 
dred inhabitants of the forest; till, arriving at maturity, its majes¬ 
tic form towers above all the junior or less vigorous trees.* 
* It is contended by Dr. Darwin, and other writers on vegetable physiology, 
that each annual shoot should be regarded as a collection of individual buds, 
each bud being a distinct individual plant, and the whole tree an aggregation 
of such individuals. I shall have occasion to revert to this question when I 
raw° in consider the subject of vegetable nutrition. 
The development of each branch takes place in the same man¬ 
ner, and by the same kind of process, as that of the trunk. The 
buds from which they originate, spring from the angle formed by 
the stalk which supports a leaf, and which is termed by botanists the 
axilla of that leaf. A law of symmetry is established by nature in 
the development of all the parts of plants. The leaves, in parti¬ 
cular, are frequently observed to arise in a circle, or symmetrically 
around the parent stem ; forming what is called a whorl, or, in bo¬ 
tanical language, a verticillated arrangement. In other cases they 
are found to have their origins at equal intervals of a spiral line, 
which may be conceived to be drawn along the stem, or the branch 
from which they grow. When these intervals correspond to the 
semi-circumference of the stem, the leaves alternate with one 
another on its opposite sides. 
The stems of most plants, even those that are perfectly erect, ex¬ 
hibit a tendency to a spiral growth. This is observable in the 
fibres of the wood of the pine, however straight may be the direc¬ 
tion of the whole trunk. This tendency is shown even in the 
epidermis of the cherry tree, for it may be stripped off with more 
facility in a spiral direction than in any other. The primitive di¬ 
rection of the leaves of endogenous plants is a spiral one. It is 
particularly marked also in the stems of creepers and of parasitic 
)1 ants, which are generally twisted throughout their whole length; 
a disposition evidently conducive to the purpose of their formation, 
namely, that of laying hold of the objects with which they come in 
contact, and of twining round them in search both of nourishment 
and support. The twisted stems of the hop and of ivy show this 
structure in a remarkable degree, and the purpose for which this 
tendency was given cannot be mistaken.— Roget’s Bridgewater 
Treatise. 
OF THE CHOICE OF LIVE STOCK FOR THE PURPOSES OF BREEDING OR 
FEEDING. 
The most desirable properties of live stock destined for food are con¬ 
sidered in The Code of Agriculture, in respect to size, form, a ten¬ 
dency to grow, early maturity, hardiness of constitution, prolific 
properties, quality of flesh, a disposition to fatten, and lightness of 
offal. 
Before the improvements introduced by Balcewell, the value of an 
animal was entirely judged of by its bulk ; and if a great size could 
be obtained, more regard was paid to the price the animal ultimate¬ 
ly fetched, than to the cost of its food. Of late, since breeders be¬ 
gan to calculate with more precision, small or moderate sized ani¬ 
mals have been generally preferred, for the following reasons:— 
Small sized animals are more easily kept, they thrive on shorter 
herbage, they collect food where a large animal could hardly exist, 
and thence are more profitable. Their meat is finer grained, pro¬ 
duces richer gravy, has often a superior flavor, and is commonly 
more nicely marbled, or veined with fat, especially when they have 
been fed for two years. Large animals are not so well calculated 
for general consumption as the moderate sized, particularly in hot 
weather; large animals poach pastures more than small ones ; they 
are not so active, require more rest, collect their food with more la¬ 
bor, and will only consume the nicer and more delicate sorts of 
plants. Small cows of the true dairy breeds give proportionably 
more milk than large ones. Small cattle may be fattened solely on 
grass of even moderate quality; whereas the large require the 
richest pastures, or to be stall-fed, the expense of which exhausts 
the profit of the farmer. It is much easier to porcure well-shaped 
and kindly-feeding stock of a small size than of a large one. Small 
sized cattle may be kept by many persons who cannot afford either 
to purchase or to maintain large ones, and by whom the loss, if any 
acccident should happen to them, can be more easily borne. The 
small sized sell better ; for a butcher, from a conviction that, in pro¬ 
portion to their respective dimensions, there is a greater superficies 
of valuable parts in a small than in a large animal, will give more 
money for two oxen of twelve stone each per quarter, than for one 
of twenty-four stone. 
In favor of the large sized, it is, on the other hand, contended, 
that without debating whether from their birth till they are slaugh¬ 
tered the large or small one eats most for its size, yet on the whole 
the large one will pay the grazier or farmer who fattens him as well 
for its food : that though some large oxen are coarse-grained, yet 
where attention is paid to the breed (as is the case with the Here¬ 
fordshire,) the large ox is as delicate food as the small one ; that if 
the small sized are better calculated for the consumption of private 
