Such is the bearing of geological science on two of the most important questions that have yet been raised in the field of natural theology.
Nor does it bear much less directly on a controversy to which, during the earlier half of the last century, there was no little importance attached in Britain, and which engaged on its opposite sides some of the finest and most vigorous intellects of the age and country.
The school of infidelity represented by Bolingbroke, and, in at least his earlier writings, by Soame Jenyns, and which, in a modified form, attained to much popularity through Pope"s famous "Essay," a.s.signed to man a comparatively inconsiderable s.p.a.ce in the system of the universe.
It regarded him as but a single link in a chain of mutual dependency,--a chain which would be no longer an entire, but a broken one, were he to be struck out of it, but as thus more important from his position than from his nature or his powers. You will remember that one of the sections of Pope"s first epistle to his "good St. John" is avowedly devoted to show what he terms the "absurdity of man"s supposing himself the final cause of the creation;" and though this great master of condensed meaning and brilliant point is now less read than he was in the days of our grandfathers, you will all remember the elegant stanzas in which he states the usual claims of the species only to ridicule them. It is human pride personified that he represents as exclaiming,--
"For me kind Nature wakes her genial power, Suckles each herb, and spreads out every flower, Annual for me the grape, the rose, renew The juice nectarious and the balmy dew.
For me the mine a thousand treasures brings; For me health gushes from a thousand springs; Seas roll to waft me, suns to light me rise; My footstool earth, my canopy the skies."
You will further remember how the poet, after thus reducing the claims and lowering the position of the species, set himself to show that man, viewed in relation to the place which he occupies, ought not to be regarded as an imperfect being. Man is, he said, as perfect as he ought to be. And, such being the case, the Author of all, looking, it would seem, very little after him, has just left him to take care of himself.
A cold, unfeeling abstraction, like the G.o.ds of the old Epicurean, the Great First Cause of this school is a being
"Who sees with equal eye, as G.o.d of all, A hero perish or a sparrow fall; Atoms or systems into ruin hurled, And now a bubble burst, and now a world."
Such, a.s.suredly, was not that G.o.d of the New Testament whom the Saviour of mankind revealed to his disciples as caring for all his creatures of the dust, but as caring most for the highest of all. "Are not two sparrows," he said, "sold for a farthing? and one of them shall not fall to the ground without your Father. Fear ye not, therefore; ye are of more value than many sparrows."
It was the error of this ingenious but very unsolid school, that it regarded the mere _order_ of the universe as itself an end or final cause. It reasoned respecting creation, as if it would be true philosophy to account for the origin and existence of some great city, such as the city of Washington in the United States, built, as we know, for purely political purposes, by showing that,--as it was remarkable for its order, for the rectilinear directness of its streets, and the rectangularity of its squares,--it must have been erected simply to be a perfect embodiment of regularity; and to urge further that, save in their character as component parts of a perfect whole, the House of Representatives and the mansion of the President were of no more intrinsic importance, or no more decidedly the _end_ of the whole, than any low tavern or outhouse in the lesser streets or lanes. The destruction of either the outhouse or the House of Representatives would equally form a void in the general plan of the city, regarded as an admirably arranged whole. And it was thus with the grand scheme of creation; for,
"From nature"s chain whatever link we strike, Tenth or tenth thousand, breaks the chain alike."
Nor is it in other than due keeping with such a view of creation, that its great Author should be represented as a cold abstraction, without love or regard, and equally indifferent to the man and the sparrow, to the atom and the planet. Order has respect to but the _relations_ of things or of beings,--not to the things or beings themselves; order is the _figure_ which, as mere etched points or strokes, they compose,--the legend which, as signs or characters, they form; and who cares anything for the component strokes or dots irrespective of the print, or for the component letters or words apart from the writing? The "equal eye," in such a scheme, would of necessity be an indifferent one. Against this strange doctrine, though in some measure countenanced by the glosses of Warburton in his defence of Pope, the theologians protested,--none of them, however, more vigorously than Johnson, in his famous critique on the "Free Inquiry" of Soame Jenyns. Nor is it uninteresting to mark with what a purely instinctive feeling of the right some of the better poets, whose "lyre," according to Cowper, was their "heart," protested against it too. Poor Goldsmith, when sitting a homeless vagabond on the slopes of the Alps, could exclaim in a greatly truer tone than that of his polished predecessor,--
"Creation"s heir, the world, the world is mine!"
And in Cowper himself we find all Goldsmith"s intense feeling of appropriation, that "calls the delightful scenery all its own,"
a.s.sociated
"With worthy thoughts of that unvaried love That planned, and built, and still upholds, a world So clothed with beauty, for rebellious man."
Strange to say, however, it is to the higher exponents of natural science, and in especial to the geologists, that it has been left to deal most directly with the sophistries of Bolingbroke and Pope.
Oken, a man quite as far wrong in some points as either the poet or his master, was the first to remark, and this in the oracular, enigmatical style peculiar to the German, that "man is the sum total of all the animals." Gifted, as all allow, with a peculiarly nice eye for detecting those a.n.a.logies which unite the animal world into a harmonious whole, he remarked, that in one existence or being all these a.n.a.logies converge.
Even the humbler students of the heavens have learned to find for themselves the star of the pole, by following the direction indicated by what are termed the two pointer stars in the Great Bear. And to the eye of Oken all the groups of the animal kingdom formed a sphere of constellations, each of which has its pointer stars, if I may so speak, turned towards man. Man occupies, as it were, the central point in the great circle of being; so that those lines which pa.s.s singly through each of the inferior animals stationed at its circ.u.mference, meet in him; and thus, as the focus in which the scattered rays unite, he imparts by his presence a unity and completeness to creation which it would not possess were he away. You will be startled, however, by the language in which the German embodies his view; though it may be not uninstructive to refer to it in evidence of the fact that a man may be _intellectually_ on the very verge of truth, and yet for every moral purpose infinitely removed from it. "Man," he says, "is G.o.d manifest in the flesh." And yet it may be admitted that there is a certain loose sense in which man _is_ "G.o.d manifest in the flesh." As may be afterwards shown, he is G.o.d"s _image_ manifested in the flesh; and an image or likeness _is_ a manifestation or making evident of that which it represents, whether it be an image or likeness of body or of mind.
Not less extraordinary, but greatly more sound in their application, are the views of Professor Owen,--supreme in his own special walk as a comparative anatomist. We find him recognizing man as exemplifying in his structure the perfection of that type in which, from the earliest ages, nature had been working with reference to some future development, and as _therefore_ a foreordained existence. "The recognition of an ideal exemplar for the vertebrated animals proves," he says, "that the knowledge of such a being as man must have existed before man appeared.
For the Divine mind that planned the archetype also foreknew all its modifications. The archetypal idea was manifested in the flesh under divers modifications, upon this planet, long prior to the existence of those animal species that actually exemplify it." So far Owen. And not less wonderful is the conclusion at which Aga.s.siz has arrived, after a survey of the geologic existences, more extended and minute, in at least the ichthyic department, than that of any other man. "It is evident," we find him saying, in the conclusion of his recent work, "The Principles of Zoology,"[20] "that there is a manifest progress in the succession of beings on the surface of the earth. This progress consists in an increasing similarity to the living fauna, and among the vertebrates, especially in their increasing resemblance to man. But this connection is not the consequence of a direct lineage between the faunas of different ages. There is nothing like parental descent connecting them.
The fishes of the Palaeozoic age are in no respect the ancestors of the reptiles of the Secondary age, nor does man descend from the mammals which preceded him in the Tertiary age. The link by which they are connected is of a higher and immaterial nature; and their connection is to be sought in the view of the Creator himself, whose aim in forming the earth, in allowing it to undergo the successive changes which geology has pointed out, and in creating successively all the different types of animals which have pa.s.sed away, _was to introduce man upon the surface of our globe_. MAN IS THE END TOWARDS WHICH ALL THE ANIMAL CREATION HAS TENDED FROM THE FIRST APPEARANCE OF THE FIRST PALaeOZOIC FISHES." These, surely, are extraordinary deductions. "In thy book,"
says the Psalmist, "all my members were written, which in continuance were fashioned when as yet there was none of them." And here is natural science, by the voice of two of its most distinguished professors, saying exactly the same thing.
Of the earliest known vertebrates,--the placoidal fishes of the Upper Silurian rocks,--we possess only fragments, which, however, sufficiently indicate, from their resemblance to the corresponding parts of an existing shark,--the cestracion,--that they belonged to fishes furnished with the two pairs of fins now so generally recognized as the h.o.m.ologues of the fore and hinder limbs in quadrupeds. With the second earliest vertebrates,--the ganoids of the Old Red Sandstone,--we are more directly acquainted, and know that they exhibited the true typical form,--a vertebral column terminating in a brain-protecting skull; and that, in at least the acanth, celacanth, and dipterian families, they had the limb-like fins. In the upper parts of the system the earliest reptiles leave the first known traces of the typical foot, with its five digits. Higher still in one of the deposits of the Trias we are startled by what seems to be the impression of a human hand of an uncouth ma.s.sive shape, but with the thumb apparently set in opposition, as in man, to the other fingers; we next trace the type upwards among the wonderfully developed reptiles of the Secondary periods; then among the mammals of the Tertiary ages, higher and yet higher forms appear; the mute prophecies of the coming being become with each approach clearer, fuller, more expressive, and at length receive their fulfilment in the advent of man. A double meaning attaches to the term type; and hence some ambiguity in the writings which have appeared on this curious subject. Type means a prophecy embodied in symbol; it means also what Sir Joshua Reynolds well terms "one of the general forms of nature,"--a pattern form, from which all others in the same cla.s.s or family, however numerous, are recognized as mere exceptions and aberrations. But in the geologic series both meanings converge and become one. The form or number typical as the _general_ form or number, is found typical also as a _prophecy_ of the form or number that came at length to be exemplified in the deputed lord of creation. Let us in our examples take typical numbers, as more easily ill.u.s.trated without diagrams than typical forms.
There are vertebrate animals of the second age of ichthyic existence, that, like the _Pterichthys_ and _Coccosteus_, were furnished with but two limbs. The muraenidae of recent times have no more; at least one of their number, the muraena proper, wants limbs altogether; so also do the lampreys. The snakes are equally limbless, save that the boas and pythons possess the rudiments of a single pair; and such also is the condition, among the amphibia, of all the known species of Coecilia.
And yet, notwithstanding these exceptional cases, the true typical number of limbs, as shown by a preponderating majority of the vertebrates of all ages of the world, is four. And this typical number is the human number. There is as certainly a typical number of digits too, as of the limbs which bear them. The exceptions are many. All the species of the horse genus possess but a single digit; the cattle family possess but two digits, the rhinoceros three digits, the hippopotamus four digits; many animals, such as the dog and cat, have but four digits on one pair of limbs and five on the other; whereas in some of the fishes the number of digits is singularly great,--from ten to twenty in most species, and in the rays from eighty to a hundred. And yet, as shown in the rocks, in which, however, the aberrations appear early, the true typical number is five on both the fore and hinder limbs. And such is the number in man. There is also, in at least the mammalia, a typical number of vertebrae in the neck. The three-toed sloth has nine cervical vertebrae; the manati only six; but seven is the typical number. And seven is the human number also. Man, in short, is pre-eminently what a theologian would term the antetypical existence,--the being in whom the types meet and are fulfilled. And not only do typical forms and numbers of the exemplified character meet in man, but there are not a few parts of his framework which in the inferior animals exist as but mere symbols, of as little importance as dugs in the male animal, though they acquire significancy and use in him. Such, for instance, are the many-jointed but moveless and unnecessary bones of which the stiff inflexible _fin_ of the dugong and the fore paw of the mole consist, and which exist in his arm as essential portions, none of which could be wanted, of an exquisitely flexible instrument. In other cases, the old types are exemplified serially in the growth and development of certain portions of his frame. Such is specially the case with that all important portion of it, the organ of thought and feeling. The human brain is built up by a wonderful process, during which it a.s.sumes in succession the form of the brain of a fish, of a reptile, of a bird, of a mammiferous quadruped; and, finally, it takes upon it its unique character as a human brain. Hence the remark of Oken, that "man is the sum total of all the animals;" hence, too, a recognition of type in the _history_ of the successive vertebral periods of the geologist, symbolical of the history of every individual man. It is not difficult to conceive how, on a subject of such complexity, especially if approached in an irreverent spirit, grave mistakes and misconceptions should take place. Virgil knew just enough of Hebrew prophecy to misapply, in his _Pollio_, to his great patron Octavius, those ancient predictions which foretold that in that age the Messiah was to appear.
And I am inclined to hold, that in the more ingenious speculations of the Lamarckians we have just a similar misapplication of what, emboldened by the views of Owen and Aga.s.siz, I shall venture to term the _Geologic Prophecies_.
The term is new, but the idea which it embodies, though it at first existed rather as a nice poetic instinct than as a scientifically based thought, is at least as old as the times of Herder and Coleridge. In a pa.s.sage quoted from the former writer by Dr. M"Cosh, in his very masterly work on typical forms, I find the profound German remarking of the strange resemblances which pervade all nature, and impart a general unity to its forms, that it would seem "as if on all our earth the form-abounding mother had proposed to herself but one type,--one proto-plasma,--according to which, and for which, she formed them all.
Know, then," he continues, "what this form is. It is the identical one which man also wears." And the remark of Coleridge, in his "Aids to Reflection," is still more definite. "Let us carry us back in spirit,"
he says, "to the mysterious week, the teeming work days of the Creator (as _they rose in_ VISION _before the eye of the inspired historian_) of the operations of the heavens and of the earth, in the day that the Lord G.o.d made the earth and the heavens. And who that watched their ways with an understanding heart could, as the vision evolved still advanced towards him, contemplate the filial and loyal bee, the home-building, wedded, and divorceless swallow, and, above all, the manifoldly intelligent ant tribes, with their commonwealths and confederacies, their warriors and miners, the husband folk that fold in their tiny flocks on the honey leaf, and the virgin sister with the holy instincts of maternal love detached and in selfless purity, and not say in himself, Behold the shadow of approaching humanity, the sun rising from behind in the kindling morn of creation?" There is fancy here; but it is that sagacious fancy, vouchsafed to only the true poet, which has so often proved the pioneer of scientific discovery, and which is in reality more sober and truthful, in the midst of its apparent extravagance, than the gravest cogitations of ordinary men. It is surely no incredible thing, that He who, in the dispensations of the human period, spake by type and symbol, and who, when He walked the earth in the flesh, taught in parable and allegory, should have also spoken in the geologic ages by prophetic figures embodied in the form and structure of animals. Nay, what the poet imagined, though in a somewhat extreme form, the philosophers seem to be on the very eve of confirming.
The foreknown "archetypal idea" of Owen,--"the immaterial link of connection" of all the past with all the present, which Aga.s.siz resolves into the foreordained design of the Creator,--will be yet found, I cannot doubt, to translate themselves into one great general truth, namely, that the Palaeozoic, Secondary, and Tertiary dispensations of creation were charged, like the patriarchal and Mosaic dispensations of grace, with the "shadows of better things to come." The advent of man simply as such was the great event prefigured during the old geologic ages. The advent of that Divine Man "who hath abolished death, and brought life and immortality to light," was the great event prefigured during the historic ages. It is these two grand events, equally portions of one sublime scheme, originated when G.o.d took counsel with himself in the depths of eternity, that bind together past, present, and future,--the geologic with the Patriarchal, the Mosaic, and the Christian ages, and all together with that new heavens and new earth, the last of many creations, in which there shall be "no more death nor curse, but the throne of G.o.d and the Lamb shall be in it, and his servants shall serve him."
"There is absurdity," said Pope, "in man"s conceiting himself the final cause of creation." Unless, however, man had the entire scheme of creation before him, with the further partially known scheme of which but a part const.i.tutes the grand theme of revelation, how could he p.r.o.nounce on the absurdity? The knowledge of the geologist ascends no higher than man. He sees all nature in the pre-Adamic past, pointing with prophetic finger towards him; and on even the argument of Hume,--just and solid within its proper limits,--he refuses to acquiesce in the unfounded inference of Pope. In order to prove the absurdity of "man"s conceiting himself the final cause of creation," proof of an ulterior cause,--of a higher end and aim,--must he adduced; and of aught higher than man, the geologist, as such, knows nothing. The long vista opened up by his science closes with the deputed lord of creation,--with man as he at present exists; and when, casting himself full upon revelation, the vail is drawn aside, and an infinitely grander vista stretches out before him into the future, he sees man--no longer, however, the natural, but the Divine man--occupying what is at once its terminal point and its highest apex. Such are some of the bearings of geologic science on the science of natural theology. Geology has disposed effectually and forever of the oft-urged a.s.sumption of an infinite series; it deals as no other science could have dealt with the a.s.sertion of the skeptic, that creation is a "singular effect;" it casts a flood of unexpected light on the somewhat obsolete plausibilities of Bolingbroke and Jenyns, that exhibits their utterly unsolid character; yet further, it exhibits in a new aspect the argument founded on design, and invests the place and standing of man in _creation_ with a peculiar significancy and importance, from its relation to the future. But on this latter part of my subject--necessarily of considerable extent and multiplicity, and connected rather with revealed than with natural religion--I must not now expatiate. I shall, however, attempt laying before you, on some future evening, a few thoughts on this portion of the general question, which you may at least find suggestive of others, and which, if they fail to elicit new truths, may have the effect of opening up upon an old truth or two a few fresh avenues through which to survey them. The character of man as a fellow-worker with his Creator in the material province has still to be considered in the light of geology. Man was the first, and is still the only creature of whom we know anything, who has set himself to carry on and improve the work of the world"s original framer,--who is a planter of woods, a tiller of fields, and a keeper of gardens,--and who carries on his work of mechanical contrivance on obviously the same principles as those on which the Divine designer wrought of old, and on which he works still.
It may not be wholly unprofitable to acquaint ourselves, through evidence furnished by the rocks, with the remarkable fact, that the Creator imparted to man the Divine image before he united to man"s the Divine nature.
LECTURE SIXTH.
GEOLOGY IN ITS BEARINGS ON THE TWO THEOLOGIES.
PART II.
Up till the introduction of man upon our planet, the humbler creatures, his predecessors, formed but mere figures in its various landscapes, and failed to alter or affect by their works the face of nature. They were conspicuous, not from what they _did_, but from what they _were_. At a very early period reefs of coral, the work of minute zoophytes, whitened the shallows of the ocean, or encircled with pale, ever broadening frames, solitary islands green with the shrubs and trees of extinct floras; but, though products of the animal world, they were not built up under the direction of even an instinctive intelligence, but were as entirely the results of a _vegetative_ process of mere growth as the forests or reed brakes of the old Carboniferous savannahs. At a later time an ant hill might be here and there descried, rearing its squat, brown pyramid amid the recesses of some Oolitic forest; or, in a period still more recent, the dam of the gigantic beaver might be seen extending its minute eye-like circlet of blue amid the windings of some bosky ravine of the Pliocene age; or existing as a little mound-skirted pond, with the rude half-submerged _cottage_ of the creature, its architect, rising beside it, on some rivulet of the Pleistocene. But how inconsiderable such works, compared with the wide extent of prospect in which they were included! How entirely inconspicuous rather, save when placed in the immediate foreground of the pictures into whose composition they entered! Not until the introduction of man upon earth do we find a creature whose works sensibly affect and modify the aspects of nature. But when man appears, how mighty the change which he effects!
Immediately on his creation he takes under his care the vegetable productions of use and show: it becomes his business to keep and dress a garden. He next becomes a tiller of fields, then a planter of vineyards: here he cuts down great forests; there he rears extensive woods. He makes himself places of habitation; and busy cities spring up as the trophies of his diligence and skill. His labors, as they grow upon the waste, affect the appearance of vast continents; until at length, from many a hill-top and tall spire, scarce a rood of ground can be seen on which he has not built, or sown, or planted, or around which lie has not erected his walls or reared his hedges. Man, in this great department of industry, is what none of his predecessors upon the earth ever were,--"a fellow-worker" with the Creator. He is a mighty _improver_ of creation.
We recognize that as improvement which adapts nature more thoroughly to man"s own necessities and wants, and renders it more pleasing both to his sense of the aesthetic and to his more material senses also. He adds to the beauty of the flowers which he takes under his charge,--to the delicacy and fertility of the fruits; the seeds of the wild gra.s.ses become corn beneath his care; the green herbs grow great of root or bulb, or bulky and succulent of top and leaf; the wild produce of nature _sports_ under his hand; the rose and lily broaden their disks and multiply their petals; the harsh green crab swells out into a delicious golden-rinded apple, streaked with crimson; the productions of his kitchen garden, strangely metamorphosed to serve the uses of his table, bear forms unknown to nature; an occult law of change and development inherent to these organisms meets in him with the developing instinct and ability, and they are regenerated under his surveillance. Nor is his influence over many of the animals less marked. The habits which he imparts to the parents become _nature_, in his behalf, in their offspring. The dog acquires, under his tutelage, the virtues of fidelity to a master and affection to a friend. The ox and horse learn to a.s.sist him in the labors of the fields. The udders of the cow and goat distend beneath his care far beyond the size necessary in the wild state, and supply him with rich milk, and the other various products of the dairy.
The fleece of the sheep becomes finer of texture and longer of fibre in his pens and folds; and even the indocile silkworm spins, in his sheltered conservatories, and among the mulberry trees which he has planted, a larger, and brighter, and more glistening coc.o.o.n. Man is the great creature-worker of the world,--its one created being, that, taking up the work of the adorable Creator, carries it on to higher results and n.o.bler developments, and finds a field for his persevering ingenuity and skill in every province in which his Maker had expatiated before him. He is evidently--to adopt and modify the remark of Oken--G.o.d"s image "manifest in the flesh."
Surveyed from the special point of view furnished by this peculiar nature of man, unique in creation, all the past of our planet divides into two periods;--the period, inclusive of every age known to the geologist, during which only the Creator wrought; and the period during which man has wrought, and to which all human history belongs. In such a view we are presented with two sets of works,--those of the Creator-worker, and those of the creature-worker; and the vast fund of materials on which the natural theologian frames his arguments demonstrative of design or contrivance, a.s.sumes a new significancy and interest when employed as evidence that there exists a certain correspondence of nature and intellect between the two workers, human and Divine. The ability of accomplishing the same ends by the same means,--in other words, of thinking and acting in the same practical tract,--indicates a similarity, if not ident.i.ty, of intellectual nature.
In the Chinese centre of civilization, for instance, printing, gunpowder, the mariner"s compa.s.s, with the various chemical and mechanical arts of elegant life, were originated without concert with the European centre of civilization, simply because in China, as in Europe, the same human faculties, prompted by the same tastes and necessities, had expatiated in the same tracts of invention, and had, as a consequence, educed the same results. I was much struck, when spending half an hour in a museum ill.u.s.trative of the arts in China, by the ident.i.ty of these with our own, especially in the purely mechanical departments; and again, when similarly employed in that apartment devoted, in the British Museum, to the domestic utensils of the ancient Egyptians. The ident.i.ty of the more common contrivances which I witnessed, with familiar contrivances in our own country, I regarded as altogether as conclusive of an ident.i.ty of mind in the individuals who had originated them, as if I had actually seen human creatures at work on them all. One cla.s.s of productions showed me that the potter"s wheel and the turning lathe had been known and employed as certainly in China and ancient Egypt as in Britain. Another, that their weaving processes must have been nearly the same. The Chinese know, for instance, as well as ourselves, that patterns can be delicately brought out,--as in the damasks,--without the a.s.sistance of color, simply by exposing silken or flaxen fibre at different angles to the light; and they have fallen, as their work shows, on the right methods of producing it. And the Egyptians antic.i.p.ated us in even our most homely household contrivances.
They even fermented their bread and trussed their fowls after the same fashion; and thus gave evidence, in these familiar matters, that they thought and contrived "after the manner of men." Now, in acquainting myself with the organisms of the geologic periods, I have been similarly but more deeply impressed by what I must be permitted to term the _human_ cast and character of the contrivances which they exemplified.
Not only could I understand the principles on which they were constructed, but further, not a few of them had, I found, been actually introduced into works of human invention ages ere they were discovered in the rock. What the great Creator-worker had originated in the Palaeozoic and Secondary periods, had been in after times originated by the little creature-worker, wholly unaware that his contrivance had been antic.i.p.ated, and was but a repet.i.tion of a previously executed design.
In the later geologic ages the organization of the various extinct animals so nearly resembled that of the animals which still live, that we may regard it as not inadequately represented by the ill.u.s.trations of Paley. A few such exceptional contrivances appear among the mammals of the Tertiary as that formed by the huge pickaxe-like tusks of the Dinotherium, or a few such extraordinary modifications of the ordinary mammalian framework as that exhibited in the enormously ma.s.sive pelvic arches and hinder limbs of the Mylodon and Megatherium. But not until we pa.s.s into the deposits of the Secondary period, and get among its cephalopoda, do we find a mechanism altogether unlike any with which we are acquainted among living organisms. As admirably shown by Buckland, the part.i.tions which separate into chambers all the whorls of the ammonite except the outermost one, were exquisitely adapted to strengthen, by the tortuous windings of their outer edges, a sh.e.l.l which had to combine great lightness with great powers of resistance. Itself a continuous arch throughout, it was supported by a series of continuous arches inside, somewhat resembling in form the groined ribs of the Gothic roof, but which, unlike the ponderous stone work of the mediaeval architects, were as light as they were strong. And to this combination of arches there was added, in the ribs and grooves of the sh.e.l.l, yet another element of strength,--that which has of late been introduced into iron roofs, which, by means of their corrugations,--ribs and grooves like those of the ammonite,--are made to span over wide s.p.a.ces, without the support of beams or rafters. Still more recently, the same principle has been introduced into metallic boats, which, when corrugated, like the old ammonites, are found to be sufficiently strong to resist almost any degree of pressure without the wonted addition of an interior framework. Similar evidences of design appear in the other extinct molluscs peculiar to these geologic ages, such as the hamite and turrilite. The belemnite seems to have united the principle of the float to that of the sinker, as we see both united in some of our modern life boats, which are steadied on their keel by one principle, and preserved from foundering by the other; or as we find them united by the boy in his mimic smack, which he hollows out and decks, in order to render it sufficiently light, while at the same time he furnishes it with a keel of lead, in order to render it sufficiently steady. The old articulata abound in marks of ingenious mechanical contrivance. The trilobites were covered over back and head with the most exquisitely constructed plate armor: but as their abdomens seem to have been soft and defenceless, they had the ability of coiling themselves round on the approach of danger, plate moving on plate with the nicest adjustment, till the rim of the armed tail rested on that of the armed head, and the creature presented the appearance of a ball defended at every point. In some genera, as in Calymene, the tail consisted of jointed segments till its termination; in others, as in Illaenus, there was a great caudal shield, that in size and form corresponded to the shield which covered the head; the segments of Calymene, from the flexibility of their joints, fitted close to the cerebral rim; while the same effect was produced in the inflexible shields, caudal and cephalic, of Illaenus, by their exact correspondence, and the flexibility of the connecting rings, which enabled them to fit together like two equal-sized cymbals brought into contact at every point by the hand. Nor were the ancient crinoids less remarkable for the amount of nice contrivance which their structures exhibited, than the ancient molluscs or crustaceans. In their calyx-like bodies, consisting always of many parts, we find the principle of the arch introduced in almost every possible form and modification, and the utmost flexibility secured to their stony arms by the amazing number of the pieces of which they were composed, and the nice disposition of the joints. In the Pentacrinites of the Secondary period (see Fig. 97) an immense spread of arms, about a thousand in number, and composed of about a hundred thousand separate pieces, had all the flexibility, though formed of solid lime, of a _drift_ of nets, and yet were so nicely jointed, tooth fitting into tooth in all their numerous parts, and the whole so bound together by ligament, that, with all the flexibility, they had also all the toughness and tenacity, of pieces of thread network. Human ingenuity, with the same purposes to effect, that is, the sweeping of shoals of swimming animals into a central receptacle, would probably construct a somewhat similar machine; but it would take half a lifetime to execute one equally elaborate.
[Ill.u.s.tration: Fig. 94.
AMMONITES HUMPHRIESIa.n.u.s.
(_Oolite._)]
[Ill.u.s.tration: Fig. 95.
ENCRINITES MONILIFORMIS.
(_Trias._)]
[Ill.u.s.tration: Fig. 96.
CUPRESSOCRINUS CRa.s.sUS.
(_Old Red Sandstone._)]
[Ill.u.s.tration: Fig. 97.[21]
PENTACRINUS FASCICULOSUS.
(_Lias._)]
[Ill.u.s.tration: Fig. 98.