Part 15

ALTINGIA EXCELSA, (NORFOLK-ISLAND PINE.)

From a young specimen in the Botanic Garden, Edinburgh.]

Beyond the Coal Measures terrestrial plants become extremely rare. The fossil botanist, on taking leave of the lower Carboniferous beds, quits the land, and sets out to sea; and it seems in no way surprising, that the specimens which he there adds to his herbarium should consist mainly of Fucaceæ and Conferveæ. The development hypothesis can borrow no support from the simple fact, that while a high terrestrial vegetation grows upon dry land, only algæ grow in the sea; and even did the Old Red Sandstone and Silurian systems furnish, as their vegetable organisms, fucoids exclusively, the evidence would amount to no more than simply this, that the land of the Palæozoic periods produced plants of the land, and the sea of the Palæozoic periods produced plants of the sea.

In the Upper Old Red Sandstone,—the formation of the Holoptychius and the Stagonolepis,—the only vegetable remains which I have yet seen are of a character so exceedingly obscure and doubtful, that all I could venture to premise regarding them is, that they seem to be the fragments of sorely comminuted fucoids. In the formation of the Middle Old Red,—that of the Cephalaspis and the gigantic lobster of Carmylie,—the vegetable remains are at once more numerous and better defined. I have detected among the gray micaceous sandstones of Forfarshire a fucoid furnished with a thick, squat stem, that branches into numerous divergent leaflets or fronds, of a slim parallelogrammical, grass-like form, and which, as a whole, somewhat resembles the scourge of cords attached to a handle with which a boy whips his top. And Professor Fleming describes a still more remarkable vegetable organism of the same formation, “which, occurring in the form of circular, flat patches, composed each of numerous smaller contiguous circular pieces, is altogether not unlike what might be expected to result from a compressed berry, such as the bramble or rasp.” In the Lower Old Red,—the formation of the Coccosteus and Cheiracanthus,—the remains of fucoids are more numerous still. There are gray slaty beds among the rocks of Navity, that owe their fissile character mainly to their layers of carbonized weed; and “among the rocks of Sandy-Bay, near Thurso,” says Mr. Dick, “the dark impressions of large fucoids are so numerous, that they remind one of the interlaced boughs and less bulky pine-trunks that lie deep in our mosses.” A portion of a stem from the last locality, which I owe to Mr. Dick, measures three inches in diameter; but the ill-compacted cellular tissue of the algæ is but indifferently suited for preservation; and so it exists as a mere coaly film, scarcely half a line in thickness.

The most considerable collection of the Lower Old Red fucoids which I have yet seen is that of the Rev. Charles Clouston of Sandwick, in Orkney,—a skilful cultivator of geological science, who has specially directed his palæontological inquiries on the vegetable remains of the flagstones of his district, as the department in which most remained to be done; but his numerous specimens only serve to show what a poverty-stricken flora that of the ocean of the Lower Old Red Sandstone must have been. I could detect among them but two species of plants;—the one an imperfectly preserved vegetable, more nearly resembling a club-moss than aught else which I have seen, but which bore on its surface, instead of the well-marked scales of the Lycopodiaceæ, irregular rows of tubercles, that, when elongated in the profile, as sometimes happens, might be mistaken for minute, ill-defined leaves; the other, a smooth-stemmed fucoid, existing on the stone in most cases as a mere film, in which, however, thickly-set longitudinal fibres are occasionally traceable, and which may be always distinguished from the other by its sharp-edged outline, and from the circumstance that its stems continue to retain the same diameter for considerable distances, after throwing off at acute angles numerous branches nearly as bulky as themselves. In a Thurso specimen, about two feet in length, which I owe to the kindness of Mr. Dick, there are stems continuous throughout, that, though they ramify in that space into from six to eight branches, are nearly as thick atop as at bottom. They are the remains, in all probability, of a long, flexible weed, that may have somewhat resembled those fucoids of the intertropical seas, which, streaming slantwise in the tide, rise not unfrequently to the surface in from fifteen to twenty fathoms of water; and as, notwithstanding their obscurity, they are among the most perfect specimens of their class yet found, and contrast with the stately araucarians of the Coal Measures, in a style which cannot fail to delight the heart of every assertor of the development hypothesis, I present them to the reader from Mr. Dick’s specimen, in a figure (fig. 54) which, however slight its interest, has at least the merit of being true. The stone exhibits specimens of the two species of Mr. Clouston’s collection,—the sharp-edged, finely-striated weed, a, and that roughened by tubercles, b; which, besides the distinctive character manifested on its surface, differs from the other in rapidly losing breath with every branch which it throws off, and, in consequence, runs soon to a point. The cut on the opposite page (fig. 55) represents not inadequately the cortical peculiarities of the two species when best preserved. The surface of the tubercled one will perhaps remind the Algologist of the knobbed surface of the thong or receptacle of Himanthalia lorea, a recent fucoid, common on the western coast of Scotland, but rare on the east. An Orkney specimen lately sent me by Mr. William Watt, from a quarry at Skaill, has much the appearance of one of the smaller ferns, such as the moor-worts, sea spleen-worts, or maiden-hairs. It exists as an impression in diluted black, on a ground of dark gray, and has so little sharpness of outline, that, like minute figures in oil-paintings, it seems more distinct when viewed at arm’s length than when microscopically examined; but enough remains to show that it must have been a terrestrial, not a marine plant. The accompanying print (fig. 56) may be regarded as no unfaithful representation of this unique fossil its state of imperfect keeping. The vegetation of the Silurian system, from its upper beds down till where we reach the zero of life, is, like that of the Old Red Sandstone, almost exclusively fucoidal. In the older fossiliferous deposits of the system in Sweden, Russia, the Lake Districts of England, Canada, and the United States, fucoids occur, to the exclusion, so far as is yet known, of every other vegetable form; and such is their abundance in some localities, that they render the argillaceous rocks in which they lie diffused, capable of being fired as an alum slate, and exist in others as seams of a compact anthracite, occasionally used as fuel. They also occur in those districts of Wales in which the place and sequence of the various Silurian formations were first determined, though apparently in a state of keeping from which little can be premised regarding their original forms. Sir Roderick Murchison sums up his notice of the vegetable remains of the system in the province whence it derives its name, by stating that he had submitted his specimens to “Mr. Robert Brown and Dr. Greville, and that neither of these eminent botanists were able to say much more regarding them than that they were fucoid-like bodies.”

FUCOIDS OF THE LOWER OLD RED SANDSTONE.

a. Smooth-stemmed species.

b. Tubercled species.

(One sixth nat. size, linear.)]

a. Smooth-stemmed species.

b. Tubercled species.

(Natural size.)]

Such are the vegetable organisms of the Old Red Sandstone and Silurian systems: they are the remains of the ancient marine plants of ancient marine deposits and, as such, lend quite as little support to the development hypothesis as the recent algæ of our existing seas. The case, stated in its most favorable form, amounts simply to this,—that at certain early periods,—represented by the Upper and Lower Silurian and the Old Red deposits,—the seas produced sea-plants; and that, at a certain later period,—that of the Carboniferous system,—the land produced land-plants. But even this, did it stand alone, would be a too favorable statement. I have seen, on one occasion, the fisherman bring up with his nets, far in the open sea, a wild rose-bush, that, though it still bore its characteristic thorns, was encrusted with serpula, and laden with pendulous lobularia. It had been swept from its original habitat by some river in flood, that had undermined and torn down the bank on which it grew; and after floating about, mayhap for months, had become so saturated with water, that it could float no longer. And in that single rose-bush, dragged up to the light and air from its place among Sertularia, Flustra, Serpula, and the deep-sea fucoids, I had as certain an evidence of the existence of the dicotyledonous plant, as if I had all the families of the Rosaecæ before me. Now, we are furnished by the more ancient formations with evidence regarding the existence of a terrestrial vegetation, such as that which the rose-bush in this case supplied. We cannot expect that the proofs should be numerous. In the chart of the Pacific attached to the better editions of “Cook’s Voyages,” there are several notes along the tract of the great navigator, that indicate where, in mid ocean, trees or fragments of trees had been picked up. These entries, however, are but few, though they belong to all the three voyages together: if I remember aright, there are only five entries in all,—two in the Northern, and three in the Southern Pacific. The floating shrub or tree, at a great distance from land, is of rare occurrence in even the present scene of things, though the breadth of land be great, and trees numerous; and in the times of the Silurian and Old Red Sandstone systems, when the breadth of land was apparently not great, and trees and shrubs, in consequence, not numerous, it must have been of rarer occurrence still. We learn, however, from Sir Charles Lyell, that in the “Hamilton group of the United States,—a series of beds that corresponds in many of its fossils with the Ludlow rocks of England,—plants allied to the Lepidodendra of the Carboniferous type are abundant; and that in the lower Devonian strata of New York the same plants occur associated with ferns.” And I am able to demonstrate, from an interesting fossil at present before me, that there existed in the period of the Lower Old Red Sandstone vegetable forms of a class greatly higher than either Lepidodendra or ferns.

FERN? OF THE LOWER OLD RED SANDSTONE.

(Natural size.)]

LIGNITE OF THE LOWER OLD RED SANDSTONE.

(One third nat. size, linear.)]

In my little work on the Old Red Sandstone, I have referred to an apparent lignite of the Lower Old Red of Cromarty, which presented, when viewed by the microscope, marks of the internal fibre. The surface, when under the glass, resembled, I said, a bundle of horse-hairs lying stretched in parallel lines: and in this specimen alone, it was added, had I found aught in the Lower Old Red Sandstone approaching to proof of the existence of dry land. About four years ago I had this lignite put stringently to the question by Mr. Sanderson, and deeply interesting was the result. I must first mention, however, that there cannot rest the shadow of a doubt regarding the place of the organism in the geologic scale. It is unequivocally a fossil of the Lower Old Red Sandstone. I found it partially embedded, with many other nodules half-disinterred by the sea, in an ichthyolitic deposit, a few hundred yards to the east of the town of Cromarty, which occurs more than four hundred feet over the Great Conglomerate base of the system. A nodule that lay immediately beside it contained a well-preserved specimen of the Coccosteus Decipiens; and in the nodule in which the lignite itself is contained, (fig. 57,) the practised eye may detect a scattered group of scales of Diplacanthus, a scarce less characteristic organism of the lower formation. And what, asks the reader, is the character of this very ancient vegetable,—the most ancient, by three whole formations, that has presented its internal structure to the microscope? Is it as low in the scale of development as in the geological scale? Does this venerable Adam of the forest appear, like the Adam of the infidel, as a squalid, ill-formed savage, with a rugged shaggy nature, which it would require the suggestive necessities of many ages painfully to lick into civilization? Or does it appear rather like the Adam of the poet and the theologian, independent, in its instantaneously-derived perfection, of all after development?

“Adam, the goodliest man of men since born His sons.”

Is its tissue vascular or cellular, or, like that of some of the cryptogamia, intermediate? Or what, in fine, is the nature and bearing of its mute but emphatic testimony, on that doctrine of progressive development of late so strangely resuscitated?

In the first place, then, this ancient fossil is a true wood,—a Dicotyledonous or Polycotyledonous Gymnosperm, that, like the pines and larches of our existing forests, bore naked seeds, which, in their state of germination, developed either double lobes to shelter the embryo within, or shot out a fringe of verticillate spikes, which performed the same protective functions, and that, as it increased in bulk year after year, received its accessions of growth in outside layers. In the transverse section the cells bear the reticulated appearance which distinguish the coniferæ, (fig. 58, a;) the lignite had been exposed in its bed to a considerable degree of pressure; and so the openings somewhat resemble the meshes of a net that has been drawn a little awry; but no general obliteration of their original character has taken place, save in minute patches, where they have been injured by compression or the bituminizing process. All the tubes indicated by the openings are, as in recent coniferæ, of nearly the same size; and though, as in many of the more ancient lignites, there are no indications of annual rings, the direction of the medullary rays is distinctly traceable. The longitudinal sections are rather less distinct than the transverse one; in the section parallel to the radius of the stem or bole the circular disks of the coniferæ were at first not at all detected; and, as since shown by a very fine microscope, they appear simply as double and triple lines of undefined dots, (b,) that somewhat resemble the stippled markings of the miniature painter; nor are the openings of the medullary rays frequent in the tangental section (i. e. that parallel to the bark,) (c;) but nothing can be better defined than the peculiar arrangement of the woody fibre, and the longitudinal form of the cells. Such is the character of this, the most ancient of lignites yet found, that yields to the microscope the peculiarities of its original structure. We find in it an unfallen Adam,—not a half-developed savage.

INTERNAL STRUCTURE OF LIGNITE OF LOWER OLD RED SANDSTONE.

a. Transverse section.

b. Longitudinal section, (parallel to radius, or medullary rays.)

c. Longitudinal section, (tangental, or parallel to the bark.)

(Mag. forty diameters.)]

The olive leaf which the dove brought to Noah established at least three important facts, and indicated a few more. It showed most conclusively that there was dry land, that there were olive trees, and that the climate of the surrounding region, whatever change it might have undergone, was still favorable to the development of vegetable life. And, further, it might be very safely inferred from it, that if olive trees had survived, other trees and plants must have survived also; and that the dark muddy prominences round which the ebbing currents were fast sweeping to lower levels, would soon present, as in antediluvian times, their coverings of cheerful green. The olive leaf spoke not of merely a partial, but of a general vegetation. Now, the coniferous lignite of the Lower Old Red Sandstone we find charged, like the olive leaf, with a various and singularly interesting evidence. It is something to know, that in the times of the Coccosteus and Asterolepis there existed dry land, and that that land wore, as at after periods, its soft, gay mantle of green. It is something also to know, that the verdant tint was not owing to a profuse development of the mere immaturities of the vegetable kingdom,—crisp, slow-growing lichens, or watery spore-propagated fungi that shoot up to their full size in a night,—nor even to an abundance of the more highly organized families of the liverworts and the mosses. These may have abounded then, as now; though we have not a shadow of evidence that they did. But while we have no proof whatever of their existence, we have conclusive proof that there existed orders and families of a rank far above them. On the dry land of the Lower Old Red Sandstone, on which, according to the theory of Adolphe Brogniart, nothing higher than a lichen or a moss could have been expected, the ship-carpenter might have hopefully taken axe in hand, to explore the woods for some such stately pine as the one described by Milton,—

“Hewn on Norwegian hills, to be the mast Of some great admiral.”