ABRIDGMENT OF THE CONTEMPLATION OF NATURE
BY Mr. Bonnet, of GENEVA

CHAPTER VI
OF VEGETABLE ECONOMY

  1. There is no source of physical relations that is more abun­dant than the economy of organized bodies. Let us cast an eye on what it offers to us on the most interesting nature. Our plan does not lead us to dive into a subject that exhausts the sagacity of a philosopher.

Organical economy, taken in the most extensive sense, is that sys­tem of laws according to which the vital functions operate in Organ­ized bodies.

Considered in a less view, organical economy presents us with two classes of objects. The first comprehends the structure, arrange­ment, and exercise of the different parts of organized bodies. The second comprises the various effects that result from organization.

2. The plant vegetates, is nourished, grows, and multiplies. The saline, unctuous, and subtile slime, which the water separates from the coarse earth, and keeps in a dissolved state, is the principal nutri­ment of plants.. T he different species of manure only contribute to the fertilizing of land, in proportion, as they introduce into it a great quantity of a spongy powder, or active salt. If a natural philosopher succeeds in raising plants, and causing them to. bear flowers and fruits in other matters than earth, for- instance, in the powder of rotten wood, deal, saw-dust, very fine sand, moss, cotton, paper. sponges: the reason is, because several of these matters either change insensibly in the ground, or actually contain earthy parts, or the water which moistens them is itself charged with these particles, which the organs extract, prepare, and assimilate.

After having been admitted into the body of the root by the extremity of the fibres, the nutricious juice rises into the ligneous fibres, from the trunk or stalk, and passes into the utricles that adhere to them. it is there prepared and digested. It after­ward enters into the proper vessels, under the form of a coloured fluid, more or less thick, which we may conjecture to be with respect to the plant, what the chyle or blood is to the animal. Being filtered by finer or more winding pipes, it is at last conveyed to all the parts, whereto it unites itself, and increases their bulk.

The extreme fineness of the canals for the sap, which renders them in some measure capillary pipes, the action of the air on the elastic sheaths of the air-vents, and the impression of these last on the ligneons fibres their contain, or by which they are comprised, the heat that rarefies the sap, and above all, that which, by act­ing on the surface of the leaves, draws thither the superfluous nutricious juice, and occasions the evaporation of it, seem to be the principal causes of the ascent of this fluid in plants. The quan­tity of nutriment, which a plant derives from the earth is in pro­portion to the number and size of its leaves; the smaller or fewer in number the leaves are, the less it draws. The nutrition of vegetables is likewise effected immediately by their leaves. They (10 not only serve for raising the sap, preparing it, and discharging its superfluity; they are moreover a kind of roots that pump from the air the juices they transmit to the neighbouring parts.

The dew, which rises from the ground, is the principal foundation of this aerial nourishment. The leaves present it to their inferior surface, which is always furnished with an infinite number of small pipes that are always ready to absorb it And that the leaves may receive no prejudice in the exercise of this function, they are disposed with such an art on the stalk and branches, that those that immediately precede do not cover such as succeed them. Sometimes they are placed alternately on two opposite and parallel lines. Some­times they are distributed by pairs, that cross each other at right angles Sometimes they are ranged on the angles of polygons circumscribed on the branches, and so disposed that the angles of the inferior poly­gon correspond with the sides of the superior. At other times they ascend the whole length of the stalk and branches on one or more parallel spital lines.

                Ye skeptics, can you inform me why plants are disposed with so much art! You will perhaps deny that plants imbibe the dew by their inferior surface! But what would you say, were one to inform you that among leaves exactly resembling each other, and taken from the same tree, such as have been steeped by their inferior surfaces in vessels of water, have continued green for the space of whole weeks, and. even months; whilst those that have been placed, by way of experiment, with their upper surface in (he water, perished in a few days?

Herbs that are always immersed in the thickest beds of dew, and that grow much faster than trees, have their leaves formed in such a manner, that they pump in the moisture nearly alike by both surfaces, sometimes more copiously by the upper ones.

Observe, lastly, that the inferior surface of the leaves of trees is commonly less smooth and glossy and of a paler colour than the opposite -surface. This remarkable difference between the two -sides of the leaf, sufficiently indicates that they have different uses.

3. By a mechanism which is very simple, the root forces itself into the earth; the branches shoot out on each side; the leaves expose their superior surface to the open air, and their inferior surface to the earth, or the inner part of the plant. Sow a seed the contrary way; you will observe the radicle and little stalk to bend backwards; the former in order to reach the earth, and the latter to gain the air. Keep a young stalk inclined; its extremity will grow upwards. Bend the branches of all sorts of plants; cause the inferior surface of their leaves to turn toward the sky; you will soon perceive that all these leaves will turn back again, and resume their former position: which motion will be executed with a quickness proportionate to the heat of the sun, or suppleness of the leaves. Sow different kinds of seeds in a closet or cellar: carry thither some small twigs having their extremity steeped in vessels fiffi of water. The leaves of the young plants and -those of the twigs, will incline their upper surface to the windows or air-holes.

Consider the leaves of divers species of herbaceous plants; of the mallow for instance; you will remark that they follow the course of the sun. In the morning you will see them present their upper sur­face to the east; towards the middle of the day this surface will face the south: in the evening it will, be turned to the west. At night or in rainy weather these leaves will be horizontal, their inferior sur face looking towards the earth.

Trace likewise the leaves of the acacia; as soon as they are heated by the sun, you will observe all their foliages draw together by their upper surface. They will then form a kind of gutter turned towards the sun. In the night. or in moist weather you will see the foliage turned the contrary way, and contracting themselves by their inferior surface. They will then form a gutter that will face the earth. 

4. Do not seek for circulation in plants: as they are more simple than animals, everything in them is performed with less apparatus.

In the day time, the action of the beat on the leaves draws to them in abundance the nutricious juice. The small excretory vessels, that appear in the form of globules, pyramids, filaments, separate the more aqueous or gross parts of the juice that rises from the root. The air contained in the trachae of the stalk and branches, by dilating itself more and more, presses the ligneous fibres, and by that means accelerates the course of the sap, at the same time that it causes it to pene­trate into the neighbouring parts.

When night approaches, the inferior surface of the leaves begins to perform one of its principal functions. The little mouths it is pro­vided with open themselves, and receive the vapours that float in the atmosphere. The air of the trachae is confined within them; their diameter, is lessened : the ligneous fibres being less pressed, enlarge themselves and admit the-juices conveyed to them from the leaves. These juices join themselves to the residue of that which bad arisen in the day time, and the whole mass tends towards the roots.

This seems to be exactly the mechanism to which the motion of the sap may be reduced. You now see more clearly the design of the direction of the leaves, and of their admirable reverting. The infe­rior surface being intended for imbibing the dew, should face the earth, from whence this vapour rises gradually at sunset. But when I say that the principal office of this surface, at least in trees and shrubs, is to receive the dew, I would not infer that the opposite surface is incapable of it: that may perhaps absorb vapours that are more rare.

Experiments that are well made seem to prove that the inferior sur­face of the leaves of trees serve likewise for insensible perspiration. Those leaves in which this surface was endued with a matter impene­trable by water, drew in and transpired much less, in an equal time and with the same management, than leaves of the same size and like­ness, whose inferior surface had not been endued with such a varnish. It seems to have resulted from the same experiments, that there is but little perspiration by the upper surface. We may thence infer that one of its principal functions is, to serve for a shelter or defence to the lower surface : and that no doubt is the use of the glossy varnish observable on the superior surface. All which agrees with the almost spontaneous motions and directions of the leaves, and with their symmetrical distribution round the stalks and branches.

5. The plant being enclosed in miniature within the fruit or seed, there encompassed with a quantity of flour, which after being diluted by the water that has penetrated the enclosures, ferments and furnishes the germ with its first nourishment. Being moistened by the delicate milk, in proportion to its weakness, it grows from day to day. In a short time its coverings become incommodious; it endea­vours to divest itself of them, and pushes forth a little root, which proceeds to seek for more nourishing juices- in the earth. The little stalk appears in its turn, As it is destined to live in the air, it pierces the earth, and darts perpendicularly into the aerial fluid. Some­times it carries along with it the remains of the teguments that had enwrapped it in the germ state: at other times it is accompanied by two leaves, which are very different from those of a mature age; these are the seminal leaves, whose principal use is probably to refine the sap.

Though it is divested of its swaddling-clothes, if we may so term them, the young plant is not at full liberty. It is not in a condition to be exposed so early to the impressions of the air and sun. All the parts remain for a short time folded together, nearly as they were in the seed. But the root, by extending and ramifying itself more and more, conveys to the vessels a considerable quantity of sap, which soon opens all the organs.

At its first appearance the plant is almost gelatinous. It assumes by little and little a greater degree of consistence by the incorporation of the juices which flow to it from all parts. That part of the stalk next the root increases in bulk, extends itself, and hardens first of all. As the hardening augments, the extension diminishes. At length it entirely ceases in this part, anti continues in that which immediately follows. Such is the nature of the progression observed in the whole plant.

Wood, whose hardness is sometimes equal to that of stone, is formed of a succession of concentric layers, that are detached every year from the inside of the rind, and harden as they advance in age.

6. Vegetables multiply by seed, shoots and slips. The pistil and stamina are to plants what the organs of generation are to animals. The former encloses the seed; the fine powder of the latter fecun­dates it. Both sexes are frequently united in the same subject: and those species are real hermaphrodites. Others bear the pistil on one branch, and the stamina on another. A third sort are like the greater part of animals, distinct males and females. The former are fur­nished with a pistil, and the latter with stamina. This is all we know with regard to the generation of plants.

When the stamina are cut off, the seed remains unfruitful. The same thing happens when any one that has pistils has not in its neigh­bourhood another provided with stamina. The pistil is always so disposed as to be able to receive the dust of the stamina. Its top is perforated with holes proportioned to the diameter of the grains of this dust, and its inside is divided into several canals, whose diameter diminishes the nearer they approach to the bottom. At the base of the pistil the seed is deposited. Every grain of the dust of the sta. mina is a box, wherein floats, in a kind of very thin vapour, an infinite multitude of other very minute grains. This box opens itself to the moisture, and discharges a small mist of globules or grains.

The shrinking of the trunks indicates that the containing globules do not reach to the bottom of the pistil: but the contained globules or grains are set at liberty by the action of the moisture which the trunk imbibes, which by opening the little box that encloses them, permits them by this means to penetrate to the ovary.

7. Vegetables multiply by shoots. They push forth from the cir­cumference of their root several suckers, which become plants them selves, and propagate their species in like manner. The branches and young shoots may likewise be considered as ingrafted on the principal plant, making one body with it. The germs which are dispersed within the plant, enfold themselves there without any Sen­sible fecundation, and reach to the surface of the bark. They appear there in the form of a small oblong and rounded body, composed of: several parts, ranged in a very regular manner, and shaped like tubes, shells, &c. This little body is the bud, which like the seed, encloses the young plant under several coverings, all the parts of which are completed with abundance of art.

The little stalk shoots forth a similar bud at its upper extremity. This bud opens, and produces a second stalk, grafted on the first, which it lengthens. This new stalk produces a third ; the third a fourth, and so on successively. When the tree has attained its full growth, it is composed of a series of small trees, placed end to end. it is the same with respect to branches and boughs, all having one and the same life, and forming only one organical whole.

Bulbous plants, instead of young shoots, send forth suckers. The bulb, which is formed of several membranes, or coats placed on each other, contains, in like manner, as the seed and bud, a plant in miniature. The sucker is a small bulb that shoots out on the sides of the principal one, and which is designed to succeed or replace it. Sometimes this replacing is performed with such quickness and cir­cumstances as are very surprising. Whilst the principal bulb is wasting, the sucker thickens and spreads itself, and in a short time becomes the principal bulb.

We may compare this bulb to a species of earth, that exhausts itself in order to furnish suitable juices to the young plant. It may also be looked upon as a placenta, that filters and prepares the nutri­cious juice. Tine leaves of some herbaceous plants form spherical masses that are pretty compact, and seem to perform the office of a bulb. The head of a cabbage spends and wastes itself in order to contribute to the unfolding of the minute stalk it contains. Place one of these heads on a vessel full of water, and it will exhibit to you the same phenomena as the bulb of a flower.

8. The branches that bend down from certain trees to the earth, take root there, and become themselves young trees. Human indus­try carries this kind of multiplication to a much greater extent. By means thereof, a single branch or root, divided into several parts, becomes SO many individual plants. What do I say? It can even cause a tree to be produced from the smallest shred of aleaf. Such is the multiplication from slips.

The organs essential to life being dispersed throughout the whole body of the subject, the slip that is detached from it, and planted in the earth, is of itself capable of forming new productions: it has every thing necessary for the unfolding of the radicals and buds. Thus a single leaf takes root, and vegetates by its own strength.

There is another kind of multiplication that is very remarkable, which consists in planting one or more slips, not in the earth, but in the trunk or branches of living trees. This is grafting; the first idea of which may perhaps have been owing to the accidental union o two branches or two fruits.*

*It has been observed by some authors that grafting has been practised from very remote antiquity. Theoprastus says that a bird having swallowed a fruit whole, cast it forth in a cleft, or cavity of a tree, where mixing with some of the putrified parts of the wood, and being washed with the rain, it budded and pro­duced within the tree, a tree of a different kind; and that hence originated the art of grafting.

The utility of grafting, is to propagate any curious sort of fruit, so as to be cer­tain of the kind, and which cannot be effected by any other method. A cion of one kind, grafted on the stock of another, may be considered merely as taking root, in the body of the tree in which it is grafted: for it is evident that the cion preserves its own proper nature, and functions, though it be fed and nourished by a mere crab.

If all trees resembled one another in their structure and juices, the size and elasticity of their vessels, &c. probably the grafts of all trees would succeed upon one another. But this is not the case. It is indispensible therefore, that there be a certain degree of congeniality between the graft, and the stock, that their pro­pensities and functions nearly correspond, that the graft may become as it were a natural branch of the stock. And this reciprocity should not only be attended to, as it respects the humours, but the seasons of fructification particularly, should be regarded, and this probably is the best criterion in this department of husbandry

There are various modes of grafting, and they are discriminated by the terms,. check-grafting cleft-grafting, crown-grafting, root-grafting, side-grafting, whip ­grafting, and in-arching. But whip-grafting, and cleft-grafting are principally used, and the former more frequently than the latter; check-grafting is perform­ed by cutting off the head of the stock horizontally, then cutting one side sloping 1 or 2 inches deep. And cutting the lower part of the graft sloping the same length, with a shoulder to rest upon the top of the stock, which is to be inserted in a slit of the stock and bound round with catgut, or a strong cord. Cleft-grafting is

The next cause of the union of the graft with its subject, is in the intercourse of the sap-vessels with each other; and this intercourse depends ultimately on the relation of their parts, and particularly on that of their consistence, and the liquors contained in them. By the assistance of a graft the gardener causes the wild stock to produce the finest fruits, he gives youth to trees, and gathers plumbs from the almond tree, and pears from the ash. Filtrating, and the prepara­tion of the juices of the subject by the vessels of the graft, occasion these productions. The roll, which is always formed at the insertion, and is composed by the interweaving of a prodigious number of fibres, is one of the principal instruments of these preparations. The more or less perfect analogy of the juices proper to the subject with those that are peculiar to the graft, favours in a greater or less degree the unfolding of the latter. The nearer or more distant relation between the time in which the sap in the subject continues, and that in which the graft has been accustomed so to do, contributes likewise more or less to the success of the operation.

performed upon stocks from about one to two inches in diameter. First with a strong knife, or small saw, the head of the stock is cut off, and one side cut sloping downwards about 1 inches. Then the cion is prepared to be inserted in a cleft of the stock which is effected with a strong knife or chisel. The cion is pre­pared by cutting it to an edge, in the shape of a knife, and which is inserted edge. ways into the cleft of the stock. If the stock is large enough, several cions may be inserted in this manner. Crown-grafting is commonly practised upon such stocks as are too large to cleave, and is often performed upon the large branches of apple, or pear trees, which already bear fruit, when it is intended to change the sorts, or renew the tree with fresh bearing wood. This should be performed in March or early in April. Thi, kind of grafting is performed, by inserting the graft about two inches between the bark and wood of the stock.—Root-grafting is performed by whip-grafting cions upon pieces of the root of any tree, of the same genus, and planting the root where it is to remain. It will take root, draw nourishment, and feed the graft.—Side-grafting is performed by inserting grafts into the sides of the stock, without heading them down; and may be practised upon trees to fill up any vacancy, or for the purpose of variety, or to have several kinds of fruit upon the same tree. It is performed by sloping of the bark and a little of the wood, and cutting the lower end of the graft to fit the incision as nearly as possible, then tying them round with catgut or strong cord, and claying them over.—Whip-grafting is always performed upon small stocks, from the size of a goose quill, to about an inch in diameter, more or less: in this kind of graft. ing it is best that the cion and the stock be nearly of a size, it is performed by preparing the cion with a tongue, about two inches, projected from a shoulder. which is to- rest evenly on the surface of the stock.—In-arching is only performed when the trees intended to be grafted, grow near each other. And it is done by inserting the branches of the one into the bark of the other, whereby they form an arch, whence the name. This being a sure method, it is commonly practised upon such trees, as are with difficulty made to succeed by any of the other methods.

An anonymous author, in a treatise published at Hamburgh, entitled amaeni tates Hortenses Novie, highly recommends a new method of grafting trees, which for beauty, flavour, and quantity of the fruit, exceeds all others, producing beautiful pyramids of fruit. This he says he had long experienced. It is performed thus.—The trees are to be transplanted in autumn, and all their branches cut off. Early in the following Summer, the young shoots are to be pruned off, and the buds are to be ingrafted into them in an inverted direction. This he says adds not only to the beauty of the pyramids, but makes the branches more fruitful. These are to be closely connected with the trunk, and to be fastened in with the common ligature: they are to be placed circularly round the tree, three buds in each circle, and these circles at six inches distance from each other. The old trees may be grafted in this manner, the success having been found very good in those of twenty years standing; but the most eligible trees are those which are young, vigorous, and full of juice, and are not above a finger or two thick, when these young trees are transplanted, they must be fenced round with pales to defend them from the violence of the wind; and there must be no dung put to

9.  The body of the plant is in a continual state of motion. It always tends to produce, either the bark, a bud, or a root. Make an incision in a tree; the wound will cicatrize. A greenish roll will in a short time be seen at the top of the wound, afterward on the sides, and at length towards the bottom. This roll is a new rind, which is about to cover the wood again, without uniting to it. Observe what passes with respect to this; you wilt perceive in it certain distinct and glutinous nipples, and small, reddish spots dispersed here and there, which you will find to be a growing bark. A matter that is partly transparent, whitish and mucilaginous will seem to raise up this bark. All these glutinous substances will thicken, increase in length, and become stronger, and in a little time, what was at first of a gluey nature, will be herbaceous, cortical, and ligneous. The cicatrice will at length entirely close itself, and restore the communication between all the vessels.

The wood does not only differ from the bark by its density, but it has likewise organs that are not to be met with in the latter. it seems to be peculiarly possessed of air-vessels. When a new rind seems to convert itself into wood, this conversion is only in appearance. Nature does not create more air-vessels than are suited to one entire plant. But a multitude of fibres that are destined to become wood, pre-exist under the new rind, and unfold themselves with it and by it, as we see the butterfly unfold itself in and by the caterpillar. Whilst wood is nothing more than a mucilaginous drop, it is not on that account the less wood, than when being transformed into a pillar, it is made to support the enormous weight of an edifice.

them till they are thoroughly rooted, for fear of rotting them before the fibres strike. The buds ingrafted must be small that the wounds made in the bark to receive them, not being very large, may heal the sooner; and if the buds do not succeed, which will be perceived in a fortnight, there must be others put in their place. The wound made to receive these buds must be parallel to the horizon; and the piece of bark taken out, must be downwards, that the rain may not get into the wound. in the autumn of the same year, this will be a green and flour­ishing pyramid, and the next summer, it ‘will flower, and ripen its fruit in autumn.

In the union of the graft with its subject, we likewise perceive a glutinous substance to spring from each of them, which spreads, ramifies, and is formed into a ball in both, becoming by degrees herbaceous, cortical. ligneous, and composes above the insertion a roll which entirely covers it. So that the whole body of the plant is furnished with small fibres on the inside, which only wait for favourable circumstances to display themselves. These circumstances are a wound, an incision, or a simple ligature. These fibres are the elements of cortical or ligneous beds, which, by spreading themselves on all sides, furnish the necessary repairs. The wound, incision and ligature, occasioning the nutricious juices to flow towards these invisible fibres, expand them, and render them perceptible to us.

What these fibres perform in the regeneration of the bark or wood, the germs effect in the reproduction of a branch or. young shoot. The fibres of the bark or wood do not unite themselves into hunches, in order to compose a bud or branch in miniature. This branch is already completely formed in its germ: it there possesses the ele­ments of all the beds, whether cortical or ligneous, which it will hereafter exhibit under different proportions.

Chapter 7