Chapter II: The Persistence of Species (2)

What shall we say to _this_ singular phenomenon? Observe yonder gigantic Fig (_Ficus Australis_) growing out of the face of that vast rocky precipice. It is not so much to the massive grandeur of the trunk, nor to the widespread head of dense foliage, that I call your attention, as to the broad expanse of roots, from the thickness of your body to that of your little finger, which have crossed and interlaced and separated and re-united, in all imaginable ways, until the whole forms a great flat network of wood, investing the surface of the rock, and following all its projections and angles with singular faithfulness, for a space of many square yards.

Would you not say, admitting that the Figs are rapid growers, that many years must have elapsed since the minute seed was dropped in yonder crevice, by some vagrant parrot that wiped his beak after breakfast on the point of rock? Would you not say that many years must have passed from the time when the tiny shoot peeped from the rocky chink, to the present moment, when the leafy honours of the crown above and the woody wall of the roots below combine to repay the protection which the plant in infancy received from its stony foster mother?

Of course you would; and most truly too, did you not know that the Fig-tree is now rejoicing in the first hour of its new-created being.

So with its noble congener here, the many-trunked Banyan (_Ficus Indica_). Although not an old tree, its canopy of broad downy leaves is already supported by so many secondary trunks, that it is not easy to say which of the larger stems is the mother trunk, and which the hopeful daughters. Every one of these stems, some just protruding from the horizontal limbs, others hanging midway between the leafy roof and the earth, some just inserting their slender spongy tips into the soil, others thick and pillar-like--is an evidence of progressive development, and therefore of lapsed time; only for the qualifying fact, that the development in this case is _prochronic_.

Here is the great _Euphorbia grandidens_ of Africa. Its stout trunk is marked with a number of holes, some four or five inches apart, arranged in perpendicular rows. In some cases they are rather depressions or pittings than holes, and look like what would result from borings made with an auger in pitch in warm weather, the margins of which had nearly closed, subsequently. What is the explanation of these marks? They are all records of time. From each of these spots once grew one of those angular prickly branches, that look like our commonest sorts of _Cactus_, and which are now confined to the summit of the trunk, arching out from it, somewhat like the branches of a candlestick.

It is the habit of this plant, when the stem has acquired a certain thickness, that the branches should, after a time, decay and drop off at the point of their union with the trunk, or rather a little below the surface, so as to leave the shallow holes or pits which we see. After their decadence, the growing bark gradually swells around the scars, and has a tendency to obliterate them. This may account for the non-appearance of them on the lower parts of the stem.

Here, then, are demonstrations of several successive stages of development. First, the stem must have been in existence before any lateral branches could have sprung from it. Secondly, the branch shot out. Thirdly, it put forth its spines and leaves. Fourthly, it died and sloughed away. Fifthly, the growing bark encroached on, and finally obliterated the cicatrice.

In this individual, all these stages are illusory, or rather they are prochronic.

See this noble Tulip-tree (_Liriodendron tulipiferum_), a giant of this primeval forest; its towering trunk is crowned with a head of large massy foliage, of a rich deep verdure, among which shine numbers of great golden tulip-like blossoms, as fragrant as beautiful.

It is, however, the leaves that grow on the terminal twigs that I wish you specially to notice. These, which, as you see, are large, and of a remarkably elegant form, are fixed at the end of long petioles, which are set alternately on the twig. Notice, now, the manner of their development; the young unexpanded leaves grow within two large leaf-like bracts, forming an oval sac, which, as the young leaf increases, swell, and at length burst, and are left on each side of the base of the leaf-stalk. There is a succession of these. On this growing twig, for instance, I find three leaves already expanded (_a a a_ in the accompanying figure), and as many pairs of these bracts (_b b b_) at their bases; the twig is terminated by a pair (_c_) convex outwardly, and whose edges are in contact with each other; if, now, I cut off one of these (as represented at _d_), I expose the next leaf (_e_) folded together, and bent downward, in its pretty manner of _vernation_; beside it is another pair of bracts (_f_), whose edges are not only in contact, but mutually adherent, and that with considerable force. On tearing these apart, I discover another smaller leaf, and another smaller pair of adhering bracts, which again contain a similar set, only yet more minute, and so on in succession, till I can no longer trace them.

Now it is manifest that the uppermost of the three leaves, together with the developing terminal bud, was at one time enclosed in the pair of bracts immediately below its base; that, before that, the middle leaf, with all above it, was similarly incarcerated in its own proper tracts; and, at a period anterior to that, the lowest leaf also. Each pair of bracts is therefore a record of a past period; and together they testify to a succession of past periods.

And yet their combined testimony is utterly worthless, because the noble tree was created in its magnificence this very day.

The beautiful twiner (_Bignonia_), which has cast its ample festoons over the topmost branches of yonder towering Mora-tree, almost concealing the natural foliage with its own elegantly pinnate leaves, and adorning it with its gorgeous trumpet-shaped flowers, is distinguished by a curious property, indicative of the years that have passed over it. In its adult maturity, as we now see it--the glory of this tropical forest--we should find, if we cut across the main stem, that its wood is divided into lobes arranged in a radiate or star-like fashion, like the divisions seen on dividing an orange transversely; and these lobes are thirty-two in number.

But this condition has not existed through the life of the plant. The wood has always been lobed, but the number of the divisions has varied, and that in geometrical ratio. Before the present stage, the constituent lobes were sixteen, which became thirty-two by the subdivision of each. In an earlier stage there were eight lobes, and, earlier still, four, which was the commencing number; the duplication having proceeded in each case by the fission of each of the existing lobes into two.[57]

Now though this phenomenon will afford us, on the data we at present possess, no insight into the age of the plant, considered as an actual chronological period, an examination of a transverse section would always determine which stage is then present, and, by consequence, how many previous stages have been passed through. And thus we obtain a distinct clue to the former history of the organism, though we cannot mark it off into months and years.

Yet the fact of creation stultifies all the conclusions that we might form from such premises; since it does, _ipso facto_, contradict every such thing as a previous history.

On this _Anona_ there is an intruder more strictly parasitical; it is a _Loranthus_, with long, club-shaped, richly-coloured blossoms. The branches of the supporting tree--a nurse who feeds her foster-child on her own vital juices--are over-spread for a large space with the shoots; which, springing each from its own disk, appear like so many distinct individuals, but are really all parts of a single plant, springing from a single seed. (For this curious fact we are indebted to the observations of Mr. Griffith, who has investigated the singular history of these parasites.)

The ripe seeds firmly adhere to the substance on which they are applied, by means of their viscid envelope, which soon hardens into a transparent glue. In the course of two or three days, the radicle curves towards its support, and, as soon as it reaches it, becomes dilated and flattened. An union is gradually formed between the woody system of the parasite and that of the stock, after which the former lives exclusively on the latter, the fibres of the sucker-like root of the parasite expanding on the wood of the support in the form of a _paté d'oie_. Up to that time the parasite had been nourished by its own albumen, which is now exhausted. As soon as the young parasite has acquired the height of one or two inches, when an additional supply of nourishment is required, a lateral shoot is sent out, which is, especially towards the point, of a green colour. This at one, or two, and subsequently at various points, adheres to the support by means of sucker-like productions, which are precisely similar in structure and mode of attachment to the original seminal one. The fibres of the parasite never penetrate beyond their original attachment; in the adult the sucker-bearing shoots frequently run to a considerable distance, many plants being literally covered with parasites, all of which have originated from one and the same seed.[58]

In this case, again, how delusive would be any inference of actual lapse of time deduced from the condition of a plant, which had been created as an adult capable of reproducing its race!

Here is a great impenetrable thicket of Prickly 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 clusters 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 interspaces 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 shore 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 institute the comparison, must be like the roof-groins of some Gothic church, supposing the interspaces 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 accumulation of vegetable cells is here! Its colossal trunk rises in naked majesty, a massive 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 noble flat "roof of inwoven shade."

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 passed, the ventricose form of the trunk was gradually lost; the bark became of a hoary grey hue or even almost white; the three-sided prickles disappeared from the bole, and were retained only on the upper surfaces of the limbs; and the great lateral buttresses began to fill up the angles which had hitherto existed between the trunk and the main horizontal and superficial roots.

I called the noble tree before us an accumulation 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 mass.

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 (_Hymenæa_) 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.

"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 space, 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._)

Leaving the vegetable kingdom, those organisms which, though beautiful indeed and instructive, are yet inanimate, let us seek others which are endowed with a higher style of life, a life which is distinguished by a measure of consciousness of the exterior world, and a perception of relations to it. Let us look for animals.

We retrace our steps to the verge of the rippling sea, where the belt of umbrageous Mangroves fringes its margin. Beneath the arching roots of these are now reposing in the warm sunlit shallows many creatures which number this as the first day of their existence. It is their natal, or rather (to make a word) their _creatal_ day.

Here is a specimen of the Sea-pen (_Pennatula_), closely resembling a rather thick and fleshy feather, with its quill-end inserted in the tenacious marl which constitutes the floor of the sea along this shore, and with the greater part of its body, including all the pinnated portion, erect, and waving lightly in the gentle swell of the bay. Its central stem is beset on each side with about twenty-five horizontal purple pinnæ, and each pinna bears from five to fifteen polypes with eight tentacles each.

Let us wade out to yonder reef. See this great mass of Millepore, growing in thin irregular perpendicular plates, which join each other at various angles, so as to form a large open honeycomb-like structure, much resembling the second stomach of an ox. It is covered with what appears a thin stratum of fawn-coloured jelly, but this consists of innumerable disks, which protrude from myriads of orifices not larger than those produced by the punctures of a fine needle; as we may discern by touching the soft slimy surface, when the whole retires, and leaves apparent only the white stony surface dotted with numberless holes, within which the disks have disappeared, and whence they will again presently re-appear.

Here too is a massive shrub of stone, a noble example of the Muricated Madrepore. It consists of a great multitude of short tranches, which are themselves branched and branched again, every part covered with little mammillary warts, and pierced with innumerable holes in which stand radiating plates of the common stone. Out of these plated orifices, especially those towards the tips of the branches, for the older ones are empty and dead, we see perpetually peeping forth, expanding for an instant, and then coyly withdrawing, lovely little green disks, surrounded with thread-like tentacles; and from the extreme end of each branch there protrudes one exactly similar to the rest in all respects, except that it is nearly twice as large. Here then are the living architects; these have secreted within their gelatinous membranes the calcareous atoms, whose aggregate forms the stony shrub before us.

Shall we try to estimate the number of polypes that have been occupied in building this tree? There are about a hundred branches, which, taken one with another, and followed along the sinuous course of their many branchlets, we may estimate to average a continuous length of eight feet each; that is, 800 feet of branch in all. Now we may consider these branches as averaging a thickness of two inches and a half in circumference, which gives us a surface of 24,000 square inches. Finally, there are about ten polype-cells in each square inch; and thus there are or have been in this coral-mass, nearly a quarter of a million of polype inhabitants.

But look at this dark crimson edifice of many stories, tier above tier, each horizontal floor of red stone sustained by a multitude of slender cylindrical pillars. When we look closely at them, we see that the pillars are tubes, perforating one or more of the floors, from the lowest tier to the uppermost.

Have we any clue to the age of these corals, or to that of either of them, supposing we did not know that they have been created to-day? Not definitely, perhaps; but indefinitely we have, certainly. In the case of the Sea-pen, the polypes have all been formed in succession; as also in that of the stony Millepore and Madrepore, with this addition, that every newly formed polype deposited an increase to the stony substance, which thus went on increasing till the great foliated or ramified mass that we see was formed.[61] And so, with this series of floors and pillars, which is the solid portion of another coral-polype, the Organ-pipe (_Tubipora musica_).

Every one of these stories has been formed in succession. From the tips of some of the tubes we see protruding an elegant polype of an emerald-green hue, having eight starry tentacles, and giving off from its base an enveloping membrane, which spreads over the rim of the tube and descends on the outside to the floor. By means of this vascular membrane, both tube and floor have been formed. Calcareous particles, deposited, one by one, in its substance, gradually built up the tube of the primary polype, or probably the tubes of the first series, the basement or ground-floor. When these tubes had arrived at a certain height, all simultaneously began to develope the fleshy membrane horizontally, which expanded until that from each touched that from its neighbour, with which it united. Meanwhile the calcareous deposition went on in this horizontal layer, and thus the first floor was made.

Now from the living vascular upper surface of this layer sprang up at certain spots buds,[62] offshoots of the common flesh, which soon rose into columns, and, by a process of calcareous deposition, became tubes with terminal polypes, which in turn spread out a horizontal layer, and thus the second floor was built. Hence a new race of polypes budded, which by and by formed the third floor; and so on in succession, until the series had attained the height which we see.

If we assume one of these stories to be the growth of a year,[63] we have ocular evidence in this specimen of six years' age, for here are six successive floors. But no: for it was created complete, as we see it, this very hour.

Yonder goes a _Medusa_, pumping its way laboriously, yet not ineffectively, just beneath the surface of the clear wave. It is a great affair, nearly a foot in diameter. Have we, from merely examining its appearance and structure, any criterion by which we can guess whether it has lived an hour, or a year, or ten years? Surely we have; for this mass of clear jelly is composed, like all other organic bodies, of cells, which have been gradually generated, by nutrition and assimilation, from the embryo.[64] This process must have occupied many months, if not several years; but the history of this Medusa did not begin when it took its present umbrella-like form. Shall we trace it back a little farther?

At some time back, then, this creature detached itself as the terminal one of many little saucer-like bodies, which had been for some time previously forming by the gradual constriction of a thick fleshy stem. Before the constriction began to be visible, this stem was the body of a white Hydraform polype, affixed by its base, and furnished at its free extremity with thirty-two tentacles. It had lived several years in this form, developing many Hydroid polypes, just like itself, by successive gemmations. Before it took this shape, which it assumed gradually, its tentacles being developed in geometrical progression, 32 from 16, from 8, from 4,--it was a soft ovoid planule clothed with vibratile cilia, which swam freely in the sea, like an _Infusorium_.

Thus the physiologist would confidently assign to this Medusa an existence of several years, as an independent organism; _nor could his conclusions be controverted_, except by the knowledge of the fact that the Medusa _has been but just now created_.

We pass on. Here is an _Echinus_. Let it be borne in mind still, that we have, _in idea_, the power of pursuing our researches on each creature at the moment which follows that of its creation; and that, when that actually was is of no consequence to our investigation.

Here then is this new-made _Echinus sphæra_, a somewhat conical globe of three inches diameter, which is covered with a forest of spines, pedicellariæ, and suckers, and which glides majestically along, with an even but slow progress, over rock and reef. Its vitals are enclosed in a hollow box of calcareous shell, which is built up of nearly a thousand pieces. This specimen, which is rather below than above the average size, is formed of ten meridional rows of large plates (the interambulacral), and ten of small (the ambulacral). The former series are each composed of thirty-two plates, making in all three hundred and twenty; the latter have just double that number, making six hundred and forty; thus this Urchin's box is built up of nine hundred and sixty plates; every one of which is of definite shape and angle, and fits into the angles of its fellows with the accuracy of the most skilfully constructed cabinet-work.

Now every one of these plates is an eloquent witness to the past life-history of the Sea-urchin. For the reason why the enclosing box is made of so many pieces is, that it might gradually expand and enlarge its capacity with the ever increasing requirements of the soft organs within. Every plate is enveloped by a vascular flesh, from which the calcareous particles are deposited in a constant and perfectly uniform ratio; and thus all the constituent plates are continually enlarged by additions to both the internal and external surfaces (increasing their strength), and to their sutural margins (increasing their combined capacity), until the adult dimensions are attained.

The size of the new-born Echinus is not nearly equal to that of one of these plates, and the progressive increase of the plates by deposition on their edges has certainly taken several years to accomplish.[65]

The same result is inferrible from the structure of the spines with which every plate is armed. Each of these is a very long cone of calcareous matter, arranged in minute oval chambers, divided by thin glassy walls, and deposited particle by particle from the thin stratum of living flesh with which each has been invested from its first embryonic development.

But of this _Echinus_, as of the _Medusa_ before, we find a history anterior to either box or spines. Its first appearance in this stage of existence was as a barely-visible circular disk, constructed on the outside of the stomach of a singular transparent organism, much like a Medusa, but of a domular form with four or six legs, stiffened by calcareous rods, and a crowning pinnacle. For some undefined time this gelatinous dome had been gliding with a stately movement through the open sea, before there was the least trace of the disk, which afterwards grew to the _Echinus_. In its earliest condition the dome itself was a soft, spherical, mulberry-like _Infusorium_, covered with vibratile cilia; this altered its form to that of a three-sided pyramid, and this to the vaulted dome.

Clearly, therefore, we have a right to infer a past history of the Urchin, and that of not a few distinct stages. But no; the specimen has commenced its history within an hour!

Yonder Feather-star (_Comatula_) notice; which, having just now started into mature life at the almighty fiat of its Creator, goes careering joyously through the sea, expanding and contracting its many-jointed and feathery arms, as if it had been accustomed to the alternation for a long life, and ever and anon settling itself by grasping the points of rock with its dorsal claws. You would hardly think that those flexible and slender arms were made of stone: yet they are; every joint of the stems and of their pinnæ is a vertebra of stone (precious stones, you will say--topaz and ruby--from their brilliant hues), which has been formed and deposited atom by atom, by the slow and gradual process of secretion of calcareous matter; the lime having been primarily collected from the sea-water which held it in solution. At least, such is the physiological deduction.

But there was a period in the _Comatula's_ history when it was not a free-swimming star, but a lily-like flower of ten slender fringed petals, seated at the summit of a long stalk, with a central columnar axis of stone. Before that, the flower-head had a bud-like figure, and the petals were minute and destitute of lateral fringes; and earlier still, it was a tiny gelatinous club without any development of stone, affixed by a spreading base, and shooting forth from the top a few pellucid processes. Earlier still, it was, no doubt, an infusory-like gemmule, clothed with cilia.

Through all these successive stages, which, of course, occupied a considerable period of time, we should certainly affirm the Feather-star to have passed, did we not know that it has this very hour burst into existence.

That Panther, whose tawny fur studded with black rosettes appeared so beautiful as he bounded with agile grace from glade to glade just as we emerged from the forest, contains within his intestines, though you cannot see it, a mature Tapeworm. The body of this parasite consists of some hundreds of square flattened segments, each of which includes a complicated generative apparatus, equal to the production of thousands of fertile ova. Is not this an evidence of age? For, first of all, consider that the formation of each of these hundreds of joints has been a work of development from the anterior parts; and therefore they record as many distinct and successive processes as there are segments. And, secondly, remember that the _Tænia_ did not commence existence as a _Tænia_, nor in the conditions in which it now exists, within the bowels of the Panther. It looks back to another form, and to another living _nidus_.

There was a time when this parasitic creature had no ribbon-like body of flattened generative segments. There was, indeed, the same curious head, a tiny globose knob at the extremity of a slender neck, furnished with the same array as now, of rows of hooks and sucking disks. But in place of the segments, the neck merged into a membranous bladder distended with clear fluid. It was not a _Tænia_ then, but a _Cysticercus_.

Its home was at that time the interior of a living animal on whose vitalized juices it was sustained, but that animal was widely different from its present patron. It was an Antelope, that cropped the wiry grass and aromatic shrubs of the arid plain.

Earlier still, the germ of this _Tænia_ was an egg lying on the ground, having been discharged from the rectum of another Panther, in the bowels of which it had been developed by one of the segments of a former _Tænia_.

Let us now trace the history of this organism onwards from the point at which we have arrived in our retrograde researches.

The parent _Tænia_, still snugly ensconced in its obscene abode, partially matured and then separated the ultimate generative segment, containing many thousands of ova, far advanced towards perfection. The detached segment now became enclosed in the fæces of the Carnivore, and was at length discharged, enveloped in the pellet. The eggs, acquiring maturity, were hatched, and the infant worms individually scattered themselves among the surrounding herbage.[66]

One of these was devoured with the herbage by a grazing Antelope, and having safely escaped the perilous ordeals of mastication and rumination, passed into the stomach of that Ruminant, whence it soon made its way by some unknown but unerring route to the liver, in the parenchyma of which organ it rapidly developed the cyst, which gave to the present stage its proper character.

The Antelope fell a prey to the ferocious Cat; its flesh was quickly digested in the stomach, but the gastric juice produced no effect on the _Cysticercus_. This parasite had merely changed its residence for one more commodious, or at least more suitable for its further development. It presently attached itself to the walls of the intestine by means of its oral hooks and suckers, and, getting rid of its vesicular sac, with its fluid contents, probably by absorption, it began to develop, joint by joint, that immense ribbon, which it possesses now, and which constitutes it a Tapeworm.

Such is the "strange eventful history" of this repulsive creature; a history legitimately deducible, in all its stages, from its presently-existing condition. But it is a history altogether illusory. The _Tænia_ never was a _Cysticercus_: the Panther is as yet guiltless of capricide: it is this moment called into being, and the Tapeworm begins existence within it.

This lump of red sandstone that has been rolled about in the sea, till all its points and angles are worn smooth, is now roughened again by the close and firm adhesion of extraneous substance, in the form of a cluster of shelly pipes, which twine irregularly over the surface of the boulder, and then start up erect with open mouths. These are the tubes of a species of _Serpula_, and the worm itself is seen now slowly emerging from one of them, and introducing its conical stopper, and elegant fans of white and scarlet filaments, to the genial daylight.

Observe, however, that the tubes are not of the same diameter throughout. At the point where they start up from contact with the stone, they are considerably smaller than at the tip; and if we trace back the adherent portion along its tortuous course, we find that it constantly diminishes until it is but a slender white thread of stone. Now this slender extremity was formed first; and as the worm itself grew, so it progressively required a larger and yet a larger habitation; which was readily provided of the due dimensions, because the material, which is limestone, was secreted by the swollen collar of the worm, and being freely poured out as required, was moulded of the proper calibre by the rotatory motion of the animal, combined with the special use of certain tactile organs for the purpose.

The shelly tubes themselves afford us ocular evidence not only of their progressive formation, but also of the successive steps by which this was effected. For at certain intervals of their length we perceive rings of the common stony substance, which mark the rim or mouth of the tube as it existed after each periodic increase. The mouth of the tube is, as we see, slightly expanded in a trumpet fashion; but as the general cylindrical figure is to be maintained, the next deposit of calcareous matter is not made at the very edge of the lip, but on a ring a little way within the margin, whence it is carried up, leaving the former margin slightly projecting.

Who could hesitate to assert that a history of past time is legibly written in the annulations of these stony tubes? And yet the creatures, with their tubes, have been but this instant created.

But here is a tube of quite another construction, though inhabited by a kindred worm. It is wholly built up of sand, the inimitable architecture of the indwelling _Terebella_, who has thus succeeded in performing a task which defied the efforts of that too industrious artizan,--the familiar of the renowned Michael Scott.[67] Our worm has certainly spun a rope of sand, and one which holds together with surprising tenacity.

The instrument which our little architect wrought with are the long tentacles, which, like a tangled tuft of yellow sewing-cotton, twist and twine over the floors of sandy pools. Nothing at first sight seems less adequate for the purpose than those very slender, soft, and flexible threads. Dr. Williams shall tell us how they are used. "They consist of hollow flattened tubular filaments, furnished with strong muscular parietes. The band may be rolled longitudinally into a cylindrical form, so as to inclose a hollow cylindrical space, if the two edges of the band meet; or a semi-cylindrical space, if they only imperfectly meet. This inimitable mechanism enables each filament to take up and firmly grasp, _at any point of its length_, a molecule of sand; or, if placed in a linear series, _a row_ of molecules. But so perfect is the disposition of the muscular fibres at the extreme free end of each filament, that it is gifted with the two-fold power of acting on the sucking and on the muscular principle. When the tentacle is about to seize an object, the extremity is drawn in, in consequence of the sudden reflux of fluid in the hollow interior; by this movement a cup-shaped cavity is formed, in which the object is securely held by atmospheric pressure; this power is, however, immediately aided by the contraction of the circular muscular fibres. Such, then, are the marvellous instruments by which these peaceful worms construct their habitations."[68]

Since the slender tentacles are the implements by which the sand-tube is thus built up, it is manifest that the existence of the tube must be subsequent to the existence of the tentacles. But the _Terebella_ was at one time without tentacles; so that its history certainly reaches back to a date anterior to the existence of a tube. Several stages of life have intervened between that distinguished by the present worm-form, and its infant condition, when it swam as a ciliated undivided monad.

So, at least, we conclude from physiological data; but our conclusions are false, because contradicted by the fact that the mature animal with its case has been just now created.

* * * * *

Let us forsake the ocean-shore, and walk again through the glades of the virgin forest. A White-ant (_Termes_) crosses our path, and, by tracking him home, we speedily discover his dwelling, an enormous structure composed of gnawed wood cemented with an animal secretion, and formed into thin but very firm and hard layers. Swarms of labourers are passing in and out; and, on our breaking away a portion of the edifice, out come crowding the warriors, with formidable jaws extended widely, ready for the fight. In the interior we find numerous chambers stored with food, and nurseries occupied by young and eggs, the number of which is every hour increasing by the oviposition of the gravid female,--the queen of the city--who is lodged in an apartment in the very centre of the whole.

The entire edifice has been built around her; she is the hope of the colony, the only mother in this vast assemblage. It is therefore through her that we must look for a past history; and in her we find it. Some months ago, when she was not more than one thousandth part as large as she is now, though then adult, she migrated from some other city not less populous than this is now. It was just before the periodical rains, when, at the time of the great annual swarming, myriads of winged males and females were evolved from the pupa state, and flew out from their native city. This individual female was found by some of the workers that now compose this colony, and was immediately selected to be at once their prisoner and their queen.

We thus trace our great egg-laying Termes to a city of last year's building, in which for a time she was in an immature condition as a nymph, and before that passed a still less-developed stage as a larva. Hence her life-history goes yet farther back to an egg, originally laid by a former female in exactly the same circumstances as those in which we find this guarded and immured individual.

Thus we reason; but the female, with her host of attendants, and the house, which is inseparable from their present stage of existence, has been created to-day.

See that creature which with loud ringing hum is whirling round and round the tassel-like blossoms of this noble _Eugenia_. You would think it a bird from its massive size, but it flashes and sparkles in the sun, like a great jewel. Now it suddenly alights on one of the crimson flowers, and you may perceive that it is a beetle;--a beetle of vast size, and glittering like a lump of burnished metal;--it bears the name of Goliath,--a giant clad in polished armour.

This is his first hour of existence; now for the first time has his nervous system responded to the stimulus of the sweet air and genial sunshine. An hour ago he had no nervous system; no system of any sort; no life; no being; no anything;--he was not until this hour.

Yet if we were to ask a friend conversant with entomology his opinion on the age of this insect, he would immediately give it; not, however, as an opinion, for he would repudiate the uncertainty which such a word implies, but as an indubitable fact, resting on the infallible grounds of constant observation and undeviating experience.

"This fine _Goliathus_," he would say, "has not long, probably, emerged from a hollow case of oval form, made of particles of earth agglutinated together by a secretion from the mouth of the larva, and concealed under the surface of the ground. Within that sepulchre it has left its cerements,--the shrivelled skin of the pupa, in which it had been wrapped up motionless like a mummy, for several weeks prior to its appearance as a glittering beetle. The construction of the oval cell was the last act of the larva, a thick, massy, heavy-bodied grub, which had fattened for years by feeding on the roots of plants beneath the soil. Four years passed away[69] while yon beetle lay on its side, darkly labouring at this occupation; and before that it was a minute egg for some weeks. The specimen before us cannot be far short of five years old."

No such thing: the witness is at fault: the _Goliathus_ is not _an hour_ old.

Take notice of the swarm of Gnats, which, like a dim cloud, are uniting in choral dance and song in the beam of the setting sun. Every member of the band that "winds his shrill horn," has had an aquatic before he had an aërial existence. A week was spent, in lobster-shape, with two breathing tubes on the summit of his body, in passing alternately from the bottom to the top of yonder stagnant pool, and then back from the top to the bottom. And a month was occupied in pretty nearly the same employment, but in another mask,--in fish-like form, with the star-tipped breathing-tube projecting from the side of the tail. But for some months earlier still it was a little lenticular egg, which was agglutinated with a number of others into an oval concave boat, that floated to and fro on the surface of the pool.

And there was something worth observing in that tiny skiff of eggs; for it did, in its artful construction, carry the evidence of time back to a former generation. The eggs individually and separately would have sunk to the bottom of the water; it was, however, essential to their life that they should be in contact with the air as well as with the water. Hence they were so arranged in the aggregate, that the mass should swim, though the constituent individuals could not. To effect this, the parent Gnat, resting on the calm surface of the pool, crossed her two hind legs, and laid an egg perpendicularly in the angle so made: others were added in succession, all maintaining the perpendicular position, all glued together by a cement that resists water, but so arranged, the crossed legs being still the mould, that the outline should be spindle-shaped, while the summits of the central eggs, being a little lower than those of the outer ones, gave a concavity to the boat. So buoyant was it when finished, and the mother's legs withdrawn, that even a drop of water falling full upon it from above, would have failed to submerge it. There it floated, week after week, and month after month, all through the winter, till the genial sun of spring hatched the fish-like larvæ to begin their wriggling existence beneath the surface.

Now may we not say with confidence, that the sounding-winged insect looks back to the pupa, the pupa to the larva, the larva to the egg-boat? And more, that the form of the boat,--a form so essential that it could not have lived without it,--looked back to the crossed feet of the mother-gnat, the impress of whose angle its extremities sustained?

Of course we might reason thus: but yet we should be at fault; for the ringing swarm of merry Gnats has been this very evening created.

The Case-flies (_Phryganea_) that look like delicate moths of sober-brown hue, flitting over the surface of the pond, have, like the Gnats, spent a considerable time under water. When they were larvæ, they industriously collected small shells, fragments of stone, bits of reed, and the like matters, and, connecting them together with strong silk, made out of them slender tubes, in which they sheltered their soft bodies from harm, while their hard polished heads and shoulders projected from the open end. And after having lived through the winter (at least, but I rather think more than _one_ winter) in this state, each closed up the entrance of his castle, by spinning across its open end, a transverse screen of lattice-work, made of very strong and stout silk, which, while it should serve the purpose of keeping out evil-minded intruders, during the helpless inaction of the pupa, should at the same time admit the free ingress and egress of water necessary for its respiration.

The life of the larva, and the exercise of these, its curious instincts, are, together with the duration of the pupa stage, inseparable precedents of the imago state in which we now observe the flying insects. No, not "inseparable;" for in this case, at least, they had no existence in time; they are prochronic developments.

In this pond at our feet there is an object worthy of a moment's observation, minute though it is, for it is only visible as a speck to the unassisted eye. On one of the whorl-filaments of this tuft of _Myriophyllum_, there stands up a cylindrical tube, firmly adherent to the plant by its foot, but free at its upper end. Small as it is, this chimney is built up of hundreds of pellets, solid, round, and yellow; placed in symmetrical order, and firmly cemented together. What has made this tube? Ha! here is the little architect ready to answer for himself; he thrusts out his head and shoulders from his chimney-top, and announces his scientific cognomen as _Melicerta ringens_.

Look! he is in the very act of building now. Did you see him suddenly bow down his head and lay a brick on the top of the last course? And now he is busy making another brick; his mould is a tiny cup-shaped cavity just below his chin; his material the floating floccose atoms of vegetable refuse. Cilia along his flower-like face collect these atoms into a stream, and pour them into the cup; and cilia within the cup whirl them rapidly round and round in many rotations, until with the aid of mucus they are somewhat consolidated into a round pellet. The brick is made, and nothing remains but that it be deposited next the former, in regular progression, and this is done by the tiny [Greek: tektôn], suddenly bending his head forward, and bringing the chin-cup with exact precision to the spot.

And how long has he been engaged in this piece of work? Little more than a day. It was commenced yesterday, when the creature was not more than one-third as large as he is now. But he had lived a few hours before the commencement of his work. He was a rover before he began to be a house-keeper. In that early stage of youth and freedom, before he had made up his mind to settle in life, he had no chin-cup, no flower-like face, and of course no tube. A cylindrical gelatinous pellucid worm, he issued out of the egg, with a brush of cilia on his crown, and danced waywardly through the water. While thus occupied, his form underwent some preliminary modifications, and at length was sufficiently matured, to enable him to choose a spot for the passing of his future life, and to commence the building on which he is still engaged.

Not so. The pellet which he deposited when we began to look at him, was the first he had ever made; he had been created but that moment; and all the previous pellets of the case had been called into being just as we saw them. They were built up prochronically.

I tear a piece of bark from the trunk of this half-decayed tree, and have disclosed amidst the rank-smelling damp and rotten wood, a large _Julus_, a slow-moving creature, with some hundred-and-fifty little twinkling feet. As this specimen has attained its adult condition, it must be at least two years old; for it does not acquire its reproductive organs and perfect development till that age.[70]