The Metamorphosis of Plants (7 page)

It is now the fruit which we have to observe, and we
shall soon be convinced that this too originates in the same way as the previous parts and is subject to the same laws.
We speak here really of those vessels or capsules formed by Nature to enclose the so-called covered seeds, or rather to develop through fructification within these vessels a greater or lesser number of seeds.
It will be easy to show that these vessels may likewise be explained according to the nature and organisation of those parts of the plant we have already considered.

It is once more the retrogressive metamorphosis which brings to our notice this law of Nature.
We may often observe in pinks, for example—which just because of this irregularity are such well-known and favourite flowers—that the seed capsules transform again into leaves like those of the calyx, and that in just the same proportion the styles become shorter.
Indeed, it even happens sometimes that the fruit capsule of a pink transforms into a real and perfect calyx, the divisions of which still have tender remnants of styles and stigmas attached to them, while from the very centre of this second calyx a more or less perfect corolla develops instead of seeds.

Furthermore even in normal and constant formations Nature reveals in manifold ways the fruitfulness that lies hidden in the leaf.
Thus a leaf of the lime—a somewhat changed leaf, it is true, but none the less quite recognisably a leaf—produces from its middle vein a little stalk and on it a perfect blossom and fruit.
In
Ruscus
this manner in which the blossom and fruit rest on the leaf is still more remarkable.

Still greater—we may even say monstrous—is this inherent fruitfulness of the leaf as shown to us in ferns.
Through an inner impulse, and perhaps even without the direct operation of two sexes, they develop and scatter around innumerable seeds, or tiny germs, capable of growth, so that a single frond rivals a wide-spreading plant in fruitfulness, or even a large branching tree.

If we keep observations in mind we shall not fail to recognise the leaf-form in all seed-vessels, in spite of their manifold formations, their peculiar modifications and combinations.
So for example, many pods may be regarded as a single leaf, folded and grown together again at the edges; others again consist of several leaves grown one upon another; compound pods or capsules may be explained as composed by several leaves united around a common centre, joined at their edges but open towards one another on their inner sides.
We are convinced of this even by visual demonstration when such capsules, having become set together, burst apart after the ripening of the seed, so that each part shows itself to be an open pod or shuck.
We also see, in various types of one and the same species, a similar process taking place normally; for example, the fruit capsules of
Nigella orientalis
are formed of pods partly grown together and collected round an axis, while in
Nigella damascena
they are completely united.

Nature conceals this likeness to the leaf-form most when she forms soft and juicy or hard and woody seed-vessels.
But
even then it will not escape our notice if we know how to follow this development carefully through all its transitions.
Here it is enough to have indicated the general idea and to have shown by means of a few examples Nature's unity of purpose.
The manifold varieties of seed-capsules will afford us material for future and further consideration.

The relation of seed-vessels to the preceding parts is also made apparent in the stigma, which in many cases sits immediately upon the ovary and is inseparably united with it.
We have already shown the relation of the stigma to the leaf-form and can mention it once again as it may be seen in double poppies, where the stigmas of the seed-capsules are changed into delicate coloured petals—quite true leaf-forms.

The last and greatest expansion effected by the plant in the course of its growth comes to expression in the fruit.
It is often great, even monstrous, both in internal strength and external form.
As it usually grows bigger after fertilisation it would seem that the now more fully determined seed that is to be, while drawing the juices needed for its growth from all parts of the plant, directs them mainly to the seed-covering— or fruit—whereby the vessels of the latter are nourished, enlarged and often to a very great extent filled out and distended.
It may be inferred from what has already been said that purer forms of air have had a great share in this, and experiment has shown that the swollen pods of
Colutea
contain pure air.

On the other hand we find in the seed itself the highest degree of contraction and inner perfection.
It may often be observed that the seed transforms leaves into its immediate covering, adapting them more or less to its shape and indeed usually having the power to attach them fast to itself, entirely changing their form.
Having already seen that many seeds may develop from and within a single leaf, we shall not wonder that a single embryo should clothe itself in a leaf covering.

We see in many winged seeds traces of such leaf-forms not perfectly fitted to the seed— for example, the maple, the elm, the ash and the birch.
A very remarkable example of the way in which the rudimentary seed gradually draws together wider coverings and adapts them to its own size is given to us us by the pot marigold, with its three circles of differently formed seeds.
The outermost circle retains a form related to
the leaflets of the involucre, except that a rudimentary seed, causing the vein to buldge, makes the leaf curved; the inner side of this curved surface is then divided along its length into two parts by a membrane.
The next circle has become even more changed; the width of the leaf and the membrane have quite disappeared; on the other hand the form has lengthened to a lesser degree and the rudimentary seed is more plainly visible at the back, the little mounds more defined.
Both of these rows seem either not at all or only imperfectly fructified.
Then follows the third circle of seeds, in their true form—very rounded and with a completely fitting covering, fully developed with all its little mounds and ridges.
We see once more the powerful contraction of expanded leaf-like parts, brought about moreover through the inner power of the seed just as before we saw the petal contracted through the power of the anther.

So we have followed Nature's footsteps as thoughtfully as may be: we have traced the outward form of the plant in all its transformations—from the development out of the seed until the seed is formed once more—and, without wishing in arrogance to probe the hidden springs of impulse in Nature's operations, we have directed our attention to the outward manifestations of those powers through which the plant, step by step, transmutes one and the same organ.
In order not to abandon the thread once taken up, we have all the time been considering only annual plants.
We have simply observed the transformation of the leaves which accompany the nodes and from them have deduced all varieties of form.
All that now remains to be done, in order to give this attempt its necessary completeness, is to speak of the eyes which lie hidden beneath each leaf and develop under certain circumstances while under others they seem completely to disappear.

Every node has by nature the power to produce one or more eyes.
They appear close to the accompanying leaves, which seem to prepare and to help their formation and growth.

On the successive development of one node out of another and on the formation of a leaf at every node and an eye close by it, rests the first simple, slow process of growth by which vegetable life is propagated.

It is well known that such an eye is very like a ripe seed in its working, and that often in the eye, more easily than in the seed, the entire form of the future plant may be recognised.

Even though the point at which the root will be developed is not so easily detected in the eye, yet it is there, just as it is in the seed, and develops quickly and easily, especially under the influence of moisture.

The eye does not need cotyledons, because it is connected with the parent plant which, now completely organised, provides sufficient nourishment as long as this connection lasts.
After separation the bud is nourished either by the new plant on which it has been grafted, or by means of the roots which it forms immediately when planted in the soil.

The eye consists of nodes and leaves in a more or less developed
condition, destined to enlarge and expand the growing plant.

In effect, the side twigs which sprout from the nodes may be regarded as distinct little plants, growing on the parent plant just as the latter grows in the earth.

The comparison of seed and eye has so often been made, and especially quite recently, with such penetration and exactitude, that we can but appeal to this work with unqualified approbation.

We will only state the following: In highly organised plants nature makes a clear difference between eyes and seeds.
In more simply formed plants, however, this difference no longer seems apparent, even to the most acute observer.
There are seeds which are undoubtedly seeds, and eyes which are undoubtedly eyes, but it is only possible to conceive, and not in any outward way to see, where the line of demarcation lies between properly fertilised seeds, separated from the parent plant by the reproductive process, and propagative buds which simply push their way out from the parent plant and separate from it without any apparent cause.

Having weighed this well in our minds we may venture to think that seeds, though they differ from eyes by being completely enclosed, and from propagative buds by the visible cause of their formation and separation from the parent plant, are yet closely related to both.

We have so far tried to explain by the transformation of
the stem-leaves, the formation of single flowers and also seeds produced within a closed capsule.
Closer examination will show that in these instances no eyes are developed; indeed there is absolutely no possibility for such a development to take place.
To understand the composite flower however, as well as the compound fruit gathered around a single cone, spindle, dies or the like, we must look to the development of eyes.

We often see that stems, without preparing long beforehand or reserving their energy for the development of a single flower, bring forth blossoms already at their nodes, often continuing in this way uninterruptedly to the very tip.
This may be explained however by the theory already propounded.
All flowers developed from eyes may be regarded as distinct plants growing on the parent plant, just as the parent plant grows on the earth.
Supplied, however, as they are with purer juices by the nodes, even the first leaves of the little twigs are much more finely formed than the first leaves of the parent plant which came after the cotyledons; indeed, even the immediate formation of calyx and flower is often possible.

Even these blossoms that develop out of eyes, had they received more copious nourishment, would have become twigs and have undergone a destiny similar to that of the parent plant.

During the development of such flowers from node to node, we notice too that same transformation of the stem-leaves which we observed when the transition to the calyx took place slowly.
The leaves contract more and more, until at last they almost disappear.
They are then called bracts, and have more or less lost their leaf-like form.
Just in the same proportion as the stem becomes thinner, so do the nodes move closer together, and everything that happened in the transition to the calyx happens now, except that no particular terminal flower appears at the tip, because Nature has already fulfilled her task at each successive eye.

Now when we have contemplated well such a stem adorned at each node with a blossom, we shall more easily understand a composite flower, especially if we remember what has already been said about the origin of the calyx.

Nature forms a composite calyx, (involucre) from a number of leaves by pressing them close to one another and arranging them around an axis.
With this same strong impulse of growth she develops, so to speak, one infinite stem, producing all its eyes at the same time and as near together as possible in the form of a flower, each separate floret fructifying the seed-vessel already prepared below it.
Nor are the nodal leaves always entirely lost in this tremendous contraction.
In thistles for example (compare
Dipsacus laciniatus
), the little leaf faithfully accompanies the floret which grows from the eye situated close by it.
In many grasses, too, each flower has such a leaflet, which in this case is called a glume.

So we are led to see that the seeds of a composite flower are true eyes, formed and developed by means of the male and female organs.
We shall easily be convinced that this is so if, keeping this idea always in mind, we examine and compare the growth and manner of seeding of various plants.

Then, too, we shall not find it difficult to explain the seeds—whether enclosed within a seed-vessel or not—which are produced in the middle of a single flower.
For it comes to the same thing if a single flower surrounds a compound ovary, whose united pistils suck in the fertilising juices from the anthers and pass them on to the ovules, or if each ovule has its own pistil, and anthers and petals.

We are convinced that with a little practice it would not
be difficult to explain in this way the manifold forms of flowers and fruits.
But it would of course require complete familiarity with the above stated ideas of expansion and contraction, approximation and anastomosis, to be able to apply them in their right place as one would use algebraic formulae.
And as much depends on the exact observation and comparison of the various stages through which Nature passes, both in the forming of genera, species and varieties, and in the growth of each individual plant, a collection of illustrations made for this purpose with explanations of the different parts of the plant in botanical terminology would be both welcome and useful.
Two strange instances of proliferous flowers, if we could have them before us, would help most decidedly in upholding this theory.