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Edward Hitchcock.

The religion of geology and its connected sciences online

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operation can produce, without a vast increase of their intensity. But
this question need neither be discussed nor decided for the sake of my
present argument, since my object is to prove an identity in the nature
and laws, not in the intensity, of geological agencies.

_In the fourth place, the laws of zoölogy and botany have always been the
same on the globe._

An examination of the animals now living, amounting to some hundred
thousand species, perhaps to one or two millions, shows that they may be
arranged in four great classes. The first class embraces the vertebral
animals, distinguished by having a vertebral column, or back-bone, a
regular skeleton, and a regular nervous system. It comprehends all the
quadrupeds and bipeds, with man at their head, and is much superior to all
other classes in complexity of organization and strength of the mental
powers. The second class embraces the mollusks, or animals inhabiting
shells. They are destitute of a spinal marrow, and for the most part their
muscles are attached to the external covering, called the shell, although
this shell is sometimes internal. The third class are called articulated
animals, having envelopes connected by annulated plates, or rings. It
includes such animals as the lobster, bloodsucker, spider, and insects
generally. The fourth class have a radiated structure, and often resemble
plants, or their habitation is a stony structure. Hence they are sometimes
called zoöphytes, which means _animal plants_; or lithophytes, which means
_stony plants_. They swarm in the ocean, and some of them build up those
extensive stony structures called coral reefs.

Now, if we examine the descriptions of the organic remains in the rocks,
we find that in all ages of the world these four great classes of animals
have existed. But in the earliest times, the three last classes - the
mollusks, the articulated, and the radiated tribes - vastly preponderated,
while the vertebral class had only a few representatives; and it is not
till we rise as high as the new red sandstone, that we meet with any,
except fishes, save a few batrachians in the old red sandstone, and the
carboniferous group, detected alone by their tracks. Then the reptiles
began to appear in abundance, with tortoises and enormous birds of a low
organization, but no mammiferous animal is found, until we reach the
oölite; and scarcely any till we rise to the tertiary strata, when they
became abundant; but not so numerous as at present, though for the most
part of larger size. Thus we find that the more perfect animals have been
developed gradually, becoming more and more complex as we rise on the
scale of the rocks. But in the three other classes, there does not appear
to have been much advance upon the original types, although in numbers and
variety there has been a great increase.

The plants now growing upon the globe, amounting probably to nearly one
hundred thousand species, are divided into two great classes, by a very
decided character. Some of them have distinct flowers, and others are
destitute of them. The former are called phenogamian, or flowering plants;
and the latter cryptogamian, or flowerless plants.

At present, the flowering plants very much predominate in the flora of
every country. But in the earliest periods of organic existence, the
reverse was the case. We find, indeed but very few flowering plants, and
these of a character somewhat intermediate between flowering and
flowerless; such as the coniferæ and cycadeæ, including the pine tribe. A
few palms appeared almost as early, and some other monocotyledons. But
most of the dicotyledons did not appear till the tertiary period, where
more than two hundred species have been found. Of the three hundred
species found in and beneath the carboniferous group, two thirds are tree
ferns, or gigantic equisetaceæ. More than one third of the entire flora of
the secondary formation consists of cycadeæ; whereas, this family of
plants forms not more than the two thousandth part of the existing flora.
In short, we find the more perfect plants as well as animals to be few in
the earliest periods, and to have been gradually introduced up to the
present time. But as to the flowerless plants, most of them seem to have
been as perfect at first as they now are.

These facts teach us conclusively that the outlines of organic life on the
globe have always been the same; that the great classes of animals and
plants have always had their representatives, and that the variations
which have been introduced, have been merely adaptations to the varying
condition of the earth's surface. The higher and more complex natures,
both of animals and plants, were not introduced at first, because the
surface was not adapted to their existence; and they were brought in only
as circumstances, favorable to their development, prepared the way.

There is another fact of great interest on this subject. Even a cursory
examination of the animals and plants now on the globe, shows such a
gradation of their characters that they form a sort of chain, extending
from the most to the least perfect species. But we see at once that the
links of this chain are of very unequal length; or, rather, that there are
in some instances wide intervals between the nearest species, as if one or
more links had dropped out. How remarkable that some of these lost links
should be found among the fossil species! I will refer to a few examples.

Among existing animals no genera or tribes are more widely separated than
those with thick skins, denominated pachydermata; such as the rhinoceros
and the elephant. But among the fossil animals of the tertiary strata,
this tribe of animals was much more common; and many of them fill up the
blanks in the existing families, and thus render more perfect and uniform
the great chain of being which binds together into one great system the
present and past periods of organic life.

A similar case occurs among fossil plants. In tropical climates we find a
few species - not much over twenty - of a singular family of plants, the
cycadeæ connecting the great families of coniferæ, or dicotyledons, with
the palms, which are monocotyledonous, and the ferns, which are
acotyledonous. The chasm, however, between those great and dissimilar
classes of plants is but imperfectly filled by the few living species of
cycadeæ. But of the fossil species hitherto found above the coal
formation, almost one half are cycadeæ; so that here, too, the lost links
of the chain are supplied.

"Facts like these," says Dr. Buckland, "are inestimably precious to the
natural theologian, for they identify, as it were, the Artificer, by
details of manipulation throughout his works. They appeal to the
physiologist, in language more commanding than human eloquence; the voice
of very stocks and stones, that have been buried for countless ages in the
deep recesses of the earth, proclaiming the universal agency of one
all-directing, all-sustaining Creator, in whose will and power these
harmonious systems originated, and by whose universal providence they are,
and have at all times been, maintained." - _Bridgewater Treatise_, vol. i.
p. 502.

One other fact, showing the identity of former zoölogical laws with those
which now prevail, must not be omitted. I refer to the existence on the
globe in all past periods of organic life of the two great classes of
carnivorous and herbivorous animals; and they have always existed, too, in
about the same proportion. To the harmony and happiness of the present
system, we know that the existence and proper relative number of these
different classes are indispensable. For in order that the greatest
possible number of animals that live on vegetable food should exist, they
must possess the power of rapid multiplication, so that there should be
born a much larger number than is necessary to people the earth. But if
there existed no carnivorous races to keep in check this redundancy of
population, the world would soon become so filled with the herbivorous
races that famine would be the consequence, and thus a much greater amount
of suffering result than the sudden death inflicted by carnivorous races
now produces. To preserve, then, a proper balance between the different
species is, doubtless, the object of the creation of the carnivorous. This
system has been aptly denominated "the police of nature." And we find it
to have always existed. The earliest vertebral animals - the sauroid fishes
and sharks - were of this description. The sharks have always lived, but
the sauroid fishes became less numerous when other marine saurians were
created; and when they both nearly disappeared, during the tertiary
period, other predaceous families were introduced, more like those now in
existence.

The history of the mollusks, or animals inhabiting shells, furnishes us
with an example still more striking. These animals, as they now exist, are
divisible into the two great classes of carnivorous and herbivorous
species, being distinguished by their anatomical structure; and so has it
ever been. In the fossiliferous rocks below the tertiary, we find immense
numbers of nautili, ammonites, and other kindred genera of polythalamous
shells, called cephalopods, which were all carnivorous. And when they
nearly disappeared with the cretaceous period, there was created another
race with carnivorous propensities and organs, called trachelipods; and
those continue still to swarm in the ocean. Had they not appeared when the
cephalopods passed away, the herbivorous tribes would have multiplied to
such an extent as ultimately to destroy marine vegetation, and bring on
famine among themselves.

These examples are sufficient to prove the existence of the carnivorous
and herbivorous races in all ages and in about the same relative numbers.
And it certainly furnishes most decisive evidence of the oneness of all
these systems of organic life on the globe.

_In the fifth place, the laws of anatomy have always been the same since
organic structures began to exist._

It had long been known that the organs of animals were beautifully adapted
to perform the functions for which they were intended. But it was not till
the investigations of Baron Cuvier, within the last half century, that it
was known how mathematically exact is the relation between the different
parts of the animal frame, nor how precise are the laws of variation in
the different species, by which they are fitted to different elements,
climates, and food. It is now well known, that each animal structure
contains a perfect system of correlation, and yet the whole forms a
harmonious part of the entire animal system on the globe. But the
language of Cuvier himself will best elucidate this subject, so far as it
is capable of popular explanation.

"Every organized individual," says he, "forms an entire system of its own;
all the parts of which mutually correspond, and concur to produce a
certain definite purpose, by reciprocal reaction, or by combining towards
the same end. Hence none of these separate parts can change their forms
without a corresponding change in the other parts of the same animal, and
consequently each of these parts, taken separately, indicates all the
other parts to which it has belonged. Thus, if the viscera of any animal
are so organized as only to be fitted for the digestion of recent flesh,
it is also requisite that the jaws should be so constructed as to fit them
for devouring prey; the claws must be constructed for seizing and tearing
it to pieces; the teeth for cutting and dividing its flesh; the entire
system of the limbs, or organs of motion, for pursuing and overtaking it;
and the organs of sense, for discovering it at a distance. Nature, also,
must have endowed the brain of the animal with instinct sufficient for
concealing itself, and for laying plans to catch its necessary victims.

"In order that the jaw may be well adapted for laying hold of objects, it
is necessary that its condyle should have a certain form; that the
resistance, the moving power, and the fulcrum, should have a certain
relative position with respect to each other, and that the temporal
muscles should be of a certain size; the hollow, or depression, too, in
which these muscles are lodged, must have a certain depth; and the
zygomatic arch, under which they pass, must not only have a certain degree
of convexity, but it must be sufficiently strong to support the action of
the masseter.

"To enable the animal to carry of its prey when seized, a corresponding
force is requisite in the muscles which elevate the head; and this
necessarily gives rise to a determinate form of the vertebræ, to which
these muscles are attached, and of the occiput into which they are
inserted.

"In order that the teeth of a carnivorous animal may be able to cut the
flesh, they require to be sharp, more or less so in proportion to the
greater or less quantity of flesh which they have to cut. It is requisite
that their roots should be solid and strong, in proportion to the greater
quantity and size of the bones which they have to break to pieces. The
whole of these circumstances must necessarily influence the development
and form of all the parts which contribute to move the jaws.

"To enable the claws of a carnivorous animal to seize its prey, a
considerable degree of mobility is necessary in their paws and toes, and a
considerable strength in the claws themselves. From these circumstances,
there necessarily result certain determinate forms in all the bones of
their paws, and in the distribution of the muscles and tendons by which
they are moved. The fore arm must possess a certain facility of moving in
various directions, and consequently requires certain determinate forms in
the bones of which it is composed. As the bones of the fore arm are
articulated with the arm bone, or humerus, no change can take place in the
form or structure of the former, without occasioning correspondent changes
in the form of the latter. The shoulder-blade, also, or scapula, requires
a correspondent degree of strength in all animals destined for catching
prey, by which it likewise must necessarily have an appropriate form. The
play and action of all these parts require certain proportions in the
muscles which set them in motion, and the impressions formed by these
muscles must still farther determine the form of all these bones.

"After these observations it will easily be seen that similar conclusions
may be drawn with respect to the hinder limbs of carnivorous animals,
which require particular conformations to fit them for rapidity of motion
in general; and that similar considerations must influence the forms and
connections of the vertebræ and other bones constituting the trunk of the
body, and to fit them for flexibility and readiness of motion in all
directions. The bones, also, of the nose, of the orbit, and of the ears,
require certain forms and structures to fit them for giving perfection to
the senses of smell, sight, and hearing, so necessary to animals of prey.
In short, the shape and structure of the teeth regulate the forms of the
condyle, of the shoulder-blade, and the claws, in the same manner as the
equation of a curve regulates all its other properties; and as, in regard
to a particular curve, all its properties may be ascertained by assuming
each separate property as the foundation of a particular equation, in the
same manner a claw, a shoulder-blade, a condyle, a leg, an arm bone, or
any other bone, separately considered, enables us to discover the
description of teeth to which they have belonged; and so, also,
reciprocally, we may determine the form of the other bones from the teeth.
Thus commencing our investigations by a careful survey of any one bone by
itself, a person who is sufficiently master of the laws of organic
structure may, as it were, reconstruct the whole animal to which that bone
had belonged."

After applying the same principle to animals with hoofs, Cuvier comes to a
conclusion even more surprising. "Hence," says he, "any one who observes
merely the print of a cloven hoof, may conclude that it has been left by a
ruminant animal, and regard the conclusion as equally certain with any
other in physics or in morals. Consequently this single footmark clearly
indicates to the observer the forms of the teeth, of all the leg bones,
thighs, shoulders, and of the trunk of the body of the animal which left
the mark. It is much surer than all the marks of Zadig.

"By thus employing the method of observation, where theory is no longer
able to direct our views, we procure astonishing, results. The smallest
fragment of bone, even the most apparently insignificant apophysis,
possesses a fixed and determinate character relative to the class, order,
genus, and species of the animal to which it belonged; insomuch that when
we find merely the extremity of a well-preserved bone, we are able, by a
careful examination, assisted by analogy and exact comparison, to
determine the species to which it once belonged, as certainly as if we had
the entire animal before us. Before venturing to put entire confidence in
this method of investigation, in regard to fossil bones, I have very
frequently tried it with portions of bones belonging to well-known
animals, and always with such complete success, that I now entertain no
doubts with regard to the results which it affords."

The remarkable correlation between the parts of existing animals having
been thus proved by the most rigid and satisfactory tests, we shall
inquire with interest for the result, when Cuvier applied the same
principles to the fossil animals. If the laws of anatomical structure were
the same when these extinct races lived as they now are, these principles
will apply equally well to the bones found in the rocks; and though often
only scattered fragments are brought to light, the anatomist will be able
to reconstruct the whole animal, and present him to our view. Cuvier was
the first who solved this problem. The quarries around Paris had furnished
a vast number of bones of strange animals, and these were thrown
promiscuously into the collections of that city. Well prepared by previous
study, this distinguished anatomist went among them with the inquiry, _Can
these bones live?_ The spirit of scientific prophecy was upon him, and, as
he uttered his inspirations, _there was a noise, and behold a shaking, and
the bones came together, bone to his bone. And the sinews and the flesh
came upon them, and the skin covered them._ "I found myself," says he, "as
if placed in a charnel-house, surrounded by mutilated fragments of many
hundred skeletons of more than twenty kinds of animals, piled confusedly
around me. The task assigned me was to restore them all to their original
position. At the voice of comparative anatomy, every bone and fragment of
a bone resumed its place. I cannot find words to express the pleasure I
experienced in seeing, as I discovered one character, how all the
consequences which I predicted from it were successively confirmed; the
feet were found in accordance with the characters announced by the teeth;
the teeth in harmony with those indicated beforehand by the feet; the
bones of the legs and thighs, and every connecting portion of the
extremities, were found set together precisely as I had arranged them,
before my conjectures were verified by the discovery of the parts entire;
in short, each species was, as it were, reconstructed from a single one of
its component elements."

It is hardly necessary to say that, since this first successful
experiment, the same principles have been more thoroughly investigated and
extended with the same success into every department of fossil organic
nature. The results which have crowned the labors of such men as Agassiz,
Ehrenberg, Kaup, Goldfuss, Bronn, Blainville, Brongniart, Deshayes, and
D'Orbigny, on the continent of Europe, and of Conybeare, Buckland,
Mantell, Lindley, and Hutton, and eminently of Owen, in Great Britain,
although sustained by the most rigid principles of science, are
nevertheless but little short of miraculous; and they demonstrate most
clearly the identity of anatomical laws, in all ages, among animals and
plants of every size and character, from the lofty lepidodendra and
sigillaria to the humblest moss or sea-weed, and from the gigantic
dinotherium, mastodon, megatherium, and iguanodon, to the infinitesimal
infusoria.

_In the sixth place, physiological laws have always been the same upon the
globe._

That death has reigned in all past ages over all animated tribes, as it
now reigns, so that in that war there has never been a discharge, I need
not attempt formally to prove. For the preserved and petrified relics of
all the former races, that now lie entombed in the rocks, furnish a silent
but impressive demonstration of the former triumph of that great
physiological law, which is stamped by the signet of Jehovah upon all
existing organic natures - _Dust thou art, and unto dust shalt thou
return._

Scarcely more necessary is it to attempt to show that the same system of
reproduction for filling the chasms which death occasions, and which is
now universal in the animal and vegetable kingdoms, has always existed.
Indeed, such a system is a necessary counterpart to a system of
dissolution. And we find the same phases to this reproductive system in
ancient and in modern periods. Organic remains clearly teach us that there
have always been viviparous as well as oviparous creatures, and
gemmiparous as well as fissiparous animals and plants. The second great
physiological law of existing nature has, then, always been the same.

The character of the nourishment by which animals and plants have been
sustained has never varied. The latter have ever been nourished by
inorganic, and the former by organic, matter. Some animals have ever fed
upon the flesh of other animals, as their petrified remains, enclosing the
masticated and half-digested fragments of other animals, testify. Other
tribes have fed only upon herbs or fruits; and some were omnivorous; just,
in fact, as we find the habits of existing animals.

No less certain are we that the processes of digestion and assimilation
have ever been unchanged. We find the same organs for these purposes as in
existing animals, viz., the mouth, the stomach, the intestines, and the
blood-vessels, as the coprolites and the cololites abundantly testify. We
infer, therefore, with great confidence, the existence of gastric juice
and bile for completing the transformation of the food into blood. Indeed,
the discovery by a lady (Miss Mary Anning, of England) of that singular
secretion from which the color called _India ink_ is prepared, with the
ink-bag of the sepia, or loligo, in a petrified state, shows that the
process of secretion existed in these ancient animals; and when we find
that in all respects their structure was like that of existing animals,
although some of the softer vessels have not been preserved, we cannot
doubt but the entire process of digestion, and the conversion of blood
into bone, nerve, and muscle, was precisely the same as it now is.

In the fact, also, that we find in fossil specimens organs of respiration,
such as lungs, gills, and trachea, we learn that the process of a
circulation of blood, and its purification by means of the oxygen of the
atmosphere, have never varied. Animal heat, too, dependent as it is
essentially upon this oxygenating process, was always derived from the
same source as at present.

The perfectly preserved minute vessels of vegetables enable us, by means
of the microscope, to identify them with the plants now alive; and they
prove, too, incontestably, that the nourishment of vegetables has always
been of the same kind, and has been converted into the various proximate
principles of plants by the same processes.

Again. We have evidence that these ancient animals possessed the same
senses as their congeneric races now on the globe. We have one good
example in which that most delicate organ, the eye, is most perfectly
preserved. It is well known that the visual organ of insects and of
crustaceans is composed of a multitude - often several hundreds or
thousands - of eyes, united into one, so as to serve the purpose of a
multiplying glass; each eye producing a separate image of the object
observed. Such an eye had the trilobite. Each contained at least four
hundred nearly spherical lenses on the surface of the cornea, united into
one organ; revealing to us the interesting fact, that the relations of
light to animal organization were the same in that remote era as they now



Online LibraryEdward HitchcockThe religion of geology and its connected sciences → online text (page 21 of 39)