Part 9 (1/2)
Here is a great impenetrable thicket of p.r.i.c.kly Pear. The delicate sulphur-hued flowers expand their broad bosoms to the sun, and the swelling fruit beneath is already putting on its lovely blush of crimson. How curious are the leafless but leaf-like dilatations of the stem--these flat oval plates of parenchyma, studded with cl.u.s.ters of woody and most acute spines!--Every one of these expansions is an expression of time, as they are of course successive, though several may be formed in a single season; and not only so, but the tufts of spines, which grow at the points of intersection of crossing lines, in a network pattern, are all successive, appearing in turn as the expanded joint of the stem grows out.
The jointed dilatations themselves are, however, transitory; in the slow lapse of years the common woody axis enlarges, and the inters.p.a.ces between the oval plates become gradually filled up with cellular tissue, and thus are obliterated; the stem, as may be seen in the central part of this spreading thicket, becoming round, almost smooth, and of dense woody texture. ”This condition is the result of many years,” you say.
It is so, in the ordinary course of nature; but in the case before us, it has been educed in a totally different manner, and by a totally different energy, viz. prochronically, by the omnipotent fiat of the Creator.
We have emerged from the forest glooms, and are come within the light and the music of the sparkling sea. And here at its margin, washed by its wavelets, there has been suddenly created a Mangrove tree (_Rhizophora_), destined to be, doubtless, the fruitful parent of a grove, which by and by will fringe this flat and muddy sh.o.r.e for miles, shutting out the light and air which now freely play over the beach, and keeping in, beneath a long canopy of dense and leathery foliage, the murky vapours which will rise from the decomposition of its successive exuviations.
As yet it is a single tree, but in its perfection of maturity. And see how characteristically we find here that singular structure, or rather habit, which in Mangroves of normal development would be the effect of age. The trunk springs from the union of a number of slender arches, each forming the quadrant of a circle, whose extremities penetrate into the muddy soil. These are the roots of the tree--there are no others--that shoot out in this arched form from the base, or ”crown” of the stem, taking a very regular curve of six feet or more in length before they dip into the mud. The larger arches send out secondary shoots from their sides, which take the same curved form, but in a direction at right angles to the former; and thus a complex array of vaulted lines is formed, which, to the crabs that run beneath--if they were only able to inst.i.tute the comparison, must be like the roof-groins of some Gothic church, supposing the inters.p.a.ces to be open to the sky.
Now, normally, it would require a lapse of several years from the first dip of the radicle of the seed into the soft soil, to form these arches, and to lift the axis of the tree a foot or eighteen inches above the surface. But here the same result is achieved in a moment, by the exercise of creative power.
Look at this _Eriodendron_. What a magnificent acc.u.mulation of vegetable cells is here! Its colossal trunk rises in naked majesty, a ma.s.sive column, to the height of a hundred feet, without a branch. And then what branches! Those limbs themselves are of the bulk of ordinary forest trees; they break out, three or four on the same plane, and radiate horizontally to a vast distance, supporting a n.o.ble flat ”roof of inwoven shade.”
[Ill.u.s.tration: SILK-COTTON TREE.]
Perhaps the most remarkable feature of this majestic tree is found at the foot of the trunk, which sends out vast spurs, radiating in all directions, and extending to a circle of seventy or eighty feet in diameter. These spurs take the form of perpendicular walls of timber, commonly not more than six or eight inches thick, pretty equal in their thickness throughout, and varying in height from fifteen or twenty feet, where they spring from the trunk, to the point where they enter the soil.
Now the Silk-cotton tree has not had this form through its life. When young, say up to twenty or thirty years old, there was no appearance of spurs; the trunk was covered with a green bark, and was studded with great triangular low spines, an inch in diameter. And, what had a curious effect, the middle of the stem swelled into an ovate form, quite symmetrical on all sides. But, as years pa.s.sed, the ventricose form of the trunk was gradually lost; the bark became of a h.o.a.ry grey hue or even almost white; the three-sided p.r.i.c.kles disappeared from the bole, and were retained only on the upper surfaces of the limbs; and the great lateral b.u.t.tresses began to fill up the angles which had hitherto existed between the trunk and the main horizontal and superficial roots.
I called the n.o.ble tree before us an acc.u.mulation of vegetable cells.
And viewed in that aspect, what an irresistible evidence of the lapse of time does this vast organism present to us! since the whole of this immense structure originated in a single cell, which, by repeated acts of self-division[59] (or, possibly, other modes of reproduction), has gradually built up the ma.s.s.
Yet such a retrospect would be most fallacious in the case before us, since the plant, as a perfect compound organism, with its parts--root, trunk, limbs and leaves, and its tissues--cellular, fibrous, and vascular, has been produced by the instantaneous putting forth of the Divine volition.
Once again. More gigantic even than the towering Ceiba, this immense Locust-tree (_Hymenaea_) appears to penetrate the very sky with its crowd of foliage, which is so remote from the earth, that our eyes cannot avail to discern the forms of the leaves. The straight columnar trunk, like some triumphal monument in the midst of a great metropolis, is of so vast a bulk that a dozen of such men as you and I could scarcely embrace it with stretched arms and joined hands.[60]
Can our friend, the vegetable physiologist, help us here to form a notion of the time which would be required for the production of this tree in the ordinary way? It is the last favour we will ask of him to-day. Come, Sir, give us your thoughts on the matter.
_The Botanist._--”There is a principle which, in trees of this character, namely, such as are of exogenous structure, will determine the age with very close accuracy. Each generation of leaves sends down woody fibres, which unite into a cylinder on the outside of the wood previously formed, and beneath the bark.”
”Now, as these cylinders are in general sufficiently distinct, in those trees which renew their leaves but once in a year, it will be enough to count the concentric circles which appear on a transverse section of the trunk, and we shall obtain the number of years during which the tree has existed. In the case of this great Locust, the rule, to be sure, is rather difficult of application in that way; a transverse section of this trunk would cost a little labour. But with this circular saw, which I always carry about with me for investigations of this sort, I can take out a horizontal cylinder on each of two or three sides of the tree, by counting the layers in which I can form a tolerably accurate estimate of the number in the whole diameter.
[Ill.u.s.tration: SECTION OF EXOGENOUS TREE.]
”See; in these cylinders, which do not materially differ, there are seventy-two layers in a foot, that is, each layer is one-sixth of an inch wide. The trunk is, at the part I have tested, about fifty feet in diameter, or twenty-five feet in radius; which would therefore contain just eighteen hundred such layers. As the deposition of new wood, however, is generally more abundant in youth and middle life than in age, the layers are probably a little wider, that is, fewer in a given s.p.a.ce, as we approach the centre. For this we must make allowance, and may conjecture that this tree is probably not less than one thousand five hundred years old.”
Now whether the premises of the botanist will bear out this conclusion or not, is not a vital question. For the question at issue is, not, _How long_ it has lived, but, _Whether it has lived at all_, before the present moment. It is enough for our point that the tree does, in its concentric zones, afford ocular evidence of successive epochs of growth.
And the proof of this would be equally good, if ten layers were deposited in a year, or if one deposit were made every ten years; equally good, if there were fifteen hundred zones, or if there were but five. It would be easy to confirm the testimony of the zones by that of other parts of the structure. The dimensions of the tree itself bear a fixed and, to a certain extent, recognisable ratio to its age; every leaf on a given twig has been successively developed from a leaf-bud, the opening of which and its elongation into a twig occupied, normally, a definite period; each bough, each of those mighty limbs, was once a twig, was once an undeveloped leaf-bud, whose expansion to its present condition was a process, of which time was an inseparable and, within certain limits, a mensurable element.
If, then, we were precluded from examining any other organism, as it proceeded from the formative hand of its Creator, than this single tree, we should be amply warranted in inferring a past existence (be it longer or shorter, which is no matter) from the phenomena of its structure, which inference the fact of its creation would flatly contradict.
VIII.
PARALLELS AND PRECEDENTS.
(_Invertebrate Animals._)
”There is a kind of character in thy life That to th' observer doth thy history Fully unfold.----” (_Shakspeare._)