THE
EDINBURGH NEW
PHILOSOPHICAL JOURNAL,
EXHIBITING A VIEW OF THE
PROGRESSIVE DISCOVERIES AND IMPROVEMENTS
IN THE
SCIENCES AND THE ARTS.
CONDUCTED BY
ROBERT JAMESON,
REGIUS PROFESSOR OF NATURAL HISTORY, LECTURER ON MINERALOGY,
AND KEEPER OF THE MUSEUM IN THE UNIVERSITY OF EDINBURGH;
Fellow of the Royal Societies of London and Edinburgh; Honorary Member
of the Royal Irish Academy; of the Royal Society of Sciences of
Denmark; of the Royal Academy of Sciences of Berlin; of the Royal
Academy of Naples; of the Geological Society of France; Honorary
Member of the Asiatic Society of Calcutta; Fellow of the Royal
Linnean, and of the Geological Societies of London; of the Royal
Geological Society of Cornwall, and of the Cambridge Philosophical
Society; of the Antiquarian, Wernerian Natural History, Royal Medical,
Royal Physical, and Horticultural Societies of Edinburgh; of the
Highland and Agricultural Society of Scotland; of the Antiquarian and
Literary Society of Perth; of the Statistical Society of Glasgow; of
the Royal Dublin Society; of the York, Bristol, Cambrian, Whitby,
Northern, and Cork Institutions; of the Natural History Society of
Northumberland, Durham, and Newcastle; of the Imperial Pharmaceutical
Society of Petersburgh; of the Natural History Society of Wetterau; of
the Mineralogical Society of Jena; of the Royal Mineralogical Society
of Dresden; of the Natural History Society of Paris; of the
Philomathic Society of Paris; of the Natural History Society of
Calvados; of the Senkenberg Society of Natural History; of the Society
of Natural Sciences and Medicine of Heidelberg; Honorary Member of the
Literary and Philosophical Society of New York; of the New York
Historical Society; of the American Antiquarian Society; of the
Academy of Natural Sciences of Philadelphia; of the Lyceum of Natural
History of New York; of the Natural History Society of Montreal; of
the Franklin Institute of the State of Pennsylvania for the Promotion
of the Mechanical Arts; of the Geological Society of Pennsylvania; of
the Boston Society of Natural History of the United States; of the
South African Institution of the Cape of Good Hope; Honorary Member of
the Statistical Society of France; Member of the Entomological Society
of Stettin, &c. &c. &c.
APRIL 1850 ... OCTOBER 1850.
VOL. XLIX.
_TO BE CONTINUED QUARTERLY._
EDINBURGH:
ADAM AND CHARLES BLACK.
LONGMAN, BROWN, GREEN, & LONGMANS, LONDON.
1850.
EDINBURGH:
PRINTED BY NEILL AND COMPANY, OLD FISHMARKET.
CONTENTS.
PAGE
ART. I. Geographical Distribution of Animals. By Professor
LOUIS AGASSIZ:--
Different Views on the Subject.--Results of
Geological Observations.--Facts and
Suppositions.--Natural Limits for
Animals.--Limitations and Adaptations.--Influence
of Heights and Depths.--Distribution of
Mammalia.--Creations on each Continent.--Zoological
Provinces.--General Conclusion, 1-25
Additional Illustrations of the Geographical
Distribution of Animals:--
1. Geographical Distribution of Sturgeons, 25
2. Fishes of Lake Superior compared with those of
the other great Canadian Lakes, 27
3. General Observations; all Fresh-water Fishes of
North America different from those of Europe--Lake
Superior and the Lakes north of it constitute a
distinct Zoological District--These Fishes have been
created where they now live--Deductions from this
fact, 30
II. On the Geography and Geology of the Peninsula of
Mount Sinai, and the adjacent Countries. By JOHN
HOGG, M.A., F.R.S., F.L.S.; Honorary Secretary of
the Royal Geographical Society, &c. (With a
coloured Geological Map.) Communicated by the
Author. (Continued from Vol. xlviii., p. 219), 33
III. Synopsis of Meteorological Observations made at the
Observatory, Whitehaven, Cumberland, in the year
1849. By JOHN FLETCHER MILLER, Esq., F.R.S.,
F.R.A.S., &c. Communicated by the Author, 53
IV. The Completed Coral Island. By JAMES D. DANA,
Geologist to the American Exploratory Expedition,
&c., &c., 65
V. Biographical Notice of Leopold Pilla, the Geologist.
By H. COQUAND. Communicated by the Author, 68
VI. On the Chronological Exposition of the Periods of
Vegetation, and the different Floras which have
succeeded each other on the Earth's surface.
According to the views of M. BRONGNIART. (Concluded
from Vol. xlviii., p. 330):--
Fossil Plants of the Permian Period.--Vosgian
Period.--Jurassic Period.--Tertiary Period, 72-97
VII. Glacial Theory of the Erratics and Drift of the New
and Old Worlds. By Professor AGASSIZ:--
Glacialists and Antiglacialists.--Erratic basins
of Switzerland.--Similar phenomena observed in
other parts of Europe.--Points necessary to be
settled; first, the relation in time and
character between the Northern and the Alpine
erratics.--Traced in North America.---Not yet
settled whether any local centres of distribution
in America; but the general cause must have acted
in all parts simultaneously. This action ceased
at 35° north latitude; this incompatible with the
notion of currents.--In both hemispheres a direct
reference to the Polar Regions. Difficulty as to
so extensive formation of Ice, removed;
difficulties on the theory of Currents, the
effects contrary to experience of
Water-Action.--Erratic phenomena of Lake
Superior.--The Iceberg theory.--Description of
appearances at Lake Superior.--Drift: contains
mud, and is without fossils.--Example of
juxtaposition of stratified and unstratified
Drift, at Cambridge.--Date of these phenomena not
fully determined, but doubtless simultaneous all
over the Globe.--The various periods and kinds of
Drift distinguished.--Accompanied by change of
level in the Continent, 97-98
VIII. Description of the Marine Telescope. By JOHN ADIE,
F.R.S.E., F.R.S.S.A. Communicated by the Author, 117
IX. Experimental Investigations to Discover the Cause of
the Change which takes place in the Standard Points
of Thermometers. By JOHN ADIE, F.R.S.E., F.R.S.S.A.
Communicated by the Author, 122
X. Observations on the Discovery, by Professor Lepsius,
of Sculptured Marks on Rocks in the Nile Valley in
Nubia; indicating that, within the historical
period, the river had flowed at a higher level than
has been known in Modern Times. By LEONARD HORNER,
Esq., F.R.S.S. L. & E., F.G.S., &c. Communicated by
the Author. With a Plate, 126
XI. On the Salmon Tribe (Salmonidæ); their Classification,
Geographical Distribution, &c., 144
XII. Results of Observations made by the Rev. F. FALLOWS,
at the Cape of Good Hope, in the years 1849-30-31.
Produced under the superintendence of G. B. Airy,
Esq., Astronomer Royal, 148
XIII. Discovery of the Great Lake "Ngami" of South
Africa, 150
XIV. DR DAVY'S Brief Sketch of the Geology of the West
Indies. Communicated for the Philosophical
Journal, 158
XV. On the Differences between Progressive, Embryonic,
and Prophetic Types in the Succession of Organized
Beings through the whole range of Geological times, 160
XVI. On a New Analogy in the Periods of Rotation of the
Primary Planets discovered by DANIEL KIRKWOOD of
Pottsville, Pennsylvania, 165
XVII. SCIENTIFIC INTELLIGENCE:--
METEOROLOGY.
1. Use of Coloured Glasses to assist the View in
Fogs. 2. Ozone, 170-171
HYDROGRAPHY.
3. On the Phenomena of the Rise and Fall of the
Waters of the Northern Lakes of America. 4.
Water Thermometer. 5. On the Falls of Niagara.
6. On the Existence of Manganese in Water.
7. Arsenic in Chalybeate Springs, 172-175
GEOLOGY.
8. The Coal Formation of America. 9. River
Terraces of the Connecticut Valley, 175-177
ZOOLOGY.
10. Fossil Crinoids of the United States. 11.
Discovery of Coral Animals on the Coast of
Massachusetts. 12. On the Circulation and
Digestion of the Lower Animals. 13.
Distribution of the Testaceous Mollusca of
Jamaica. 14. Metamorphoses of the Lepidoptera.
15. On the Zoological Character of Young
Mammalia. 16. The Manatus or Sea Cow, the
Embryonic Type of the Pachydermata. 17. Fossil
Elephant and Mastodon from Africa. 18.
Cauterization in the case of Poisonous Bites.
19. Dental Parasites, 177-184
ARTS.
20. The Steamboat New World. 21. Use of Parachutes
in Mines. 22. Adulterations of Drugs. 23. To
restore Decayed Ivory. 24. Ivory as an Article
of Manufacture. 25. Flexible Ivory. 26.
Air-Whistle. 27. Curious Electrical
Phenomenon, 184-188
XVIII. List of Patents granted for Scotland from 22d March
to 22d June 1850, 189
* * * * *
_Memorandum._--New Publications will be noticed in our next Number.
MEMORANDUM.
Owing to the large space occupied by the Proceedings of the British
Association for the Promotion of Science, held at Edinburgh in the
month of August, 1850, various interesting communications are delayed
until the next number of the Philosophical Journal.
THE
EDINBURGH NEW
PHILOSOPHICAL JOURNAL.
_Geographical Distribution of Animals._
By Professor LOUIS AGASSIZ.
The greatest obstacles in the way of investigating the laws of the
distribution of organized beings over the surface of our globe, are to
be traced to the views generally entertained about their origin. There
is a prevailing opinion, which ascribes to all living beings upon
earth one common centre of origin, from which it is supposed they, in
the course of time, spread over wider and wider areas, till they
finally came into their present state of distribution; and what gives
this view a higher recommendation, in the opinion of most men, is the
circumstance, that such a method of distribution is considered as
revealed in our sacred writings. We hope, however, to be able to shew
that there is no such statement in the Book of Genesis; that this
doctrine of a unique centre of origin, and successive distribution of
all animals is of very modern invention; and that it can be traced
back for scarcely more than a century in the records of our science.
There is another view to which, more recently, naturalists have seemed
to incline; viz., the assuming several centres of origin, from which
organized beings were afterwards diffused over wider areas, in the
same manner as according to the first theory, the difference being
only in the assumption of several centres of dispersion instead of a
single one.
We have recently been led to take a very different view of the
subject, and shall presently illustrate the facts upon which the view
rests. But before we undertake to introduce more directly this
subject, there is another point which requires preliminary
investigation, which seems to have been entirely lost sight of by all
those, without exception, who have studied the geographical
distribution of animals, and which seems to us to be the keystone of
the whole edifice, whenever we undertake to reconstruct the primitive
plan of the geographical distribution of animals and plants. The
distribution of organized beings over the surface of our globe in its
present condition cannot be considered in itself; and without an
investigation, at the same time, of the geographical distribution of
those organized beings which have existed in former geological
periods, and had become extinct before those of the present creation
were called into being. For it is well ascertained now that there is a
natural succession in the plan of creation--an intimate connection
between all the types of the different periods of the creation from
its beginning up to this day; so much so, that the present
distribution of animals and plants is the continuation of an order of
things which prevailed for a time at an earlier period, but which came
to an end before the existing arrangement of things was introduced.
The animal kingdom, as we know it in our days, is therefore engrafted
upon its condition in earlier periods; and it is to the distribution
of animals in these earlier periods that we must look, if we would
trace the plan of the Creator from its commencement to its more
advanced development in our own time.
If there is any truth in the view that animals and plants originated
from a common centre, it must be at the same time shewn that such an
intimate connection between the animals existed at all periods; or, at
least, we should, before assuming such a view for the animals living
in our days, discover a sufficient reason for ascribing to them
another mode of dispersion than to the animals and plants of former
periods. But there is such a wonderful harmony in all the great
processes of nature, that, at the outset, we should be carefully on
our guard against assuming different modes of distribution for the
organized beings of former periods, and for those which at present
cover the globe. Should it be plain that the animals and plants did
not originate from a common centre at the beginning of the creation,
and during the different successive geological periods, we have at
once a strong indication that neither has such been the case with the
animals of the present day; and, on the other hand, if there were
satisfactory evidence that the animals and plants now living
originated from a common centre, we should consider the matter
carefully before trusting to the views derived from geological facts.
Let us, therefore, examine first the value of the evidence on both
sides.
We have already expressed, and we repeat here, our earnest belief that
the view of a unique centre of origin and distribution rests chiefly
upon the supposed authority of the Mosaic record; and is in no way
sustained by evidence derived from investigations in natural history.
On the contrary, wherever we trace the animals in their present
distributions, we find them scattered over the surface of our globe in
such a manner, according to such laws, and under such special
adaptations, that it would baffle the most fanciful imagination to
conceive such an arrangement as the mere results of migrations, or of
the influence of physical causes over the dispersion of both animals
and plants. For we find that all animals and plants of the arctic
zones agree in certain respects and are uniform over the three
continents which verge towards the northern pole, whilst those of the
temperate zone agree also in certain respects, but differ somewhat
from each other within definite limits, in the respective continents.
And the differences grow more and more prominent as we approach the
tropical zone, which has its peculiar Fauna and Flora in each
continent; so much so, that it is impossible for us to conceive such a
normal arrangement, unless it be the result of a premeditated plan,
carried out voluntarily according to predetermined laws.
The opinion which is considered as the Biblical view of the case, and
according to which all animals have originated in a common centre,
would leave us at a loss for any cause by which to account for the
special dispersion of animals and plants beyond the mere necessity of
removing from the crowded ground to assume wider limits, as their
increased number made it constantly more and more necessary and
imperative. According to this view, the animals of the arctic zone as
well as those of the tropics,--those of America as well as those of
New Holland,--have been first created upon the high lands of Iran, and
have taken their course in all directions, to settle where they are
now found to be strictly limited. It does not appear how such
migrations of polar animals could have taken place over the warmer
tracts of land which they had to cross, and in which they cannot even
be kept alive, in our days, with the utmost precautions: nor how the
terrestrial animals of New Holland, which have no analogies in the
main continents, could have reached that large island, nor why they
should have all moved thither. And, indeed, it is impossible, with
such a theory, to account, either for the special adaptation of types
to particular districts of the earth's surface, or for the limited
distribution of so many species which are found only over narrow
districts in their present arrangement. It is inconsistent with the
structure, habits, and natural instincts of most animals, even to
suppose that they could have migrated over any great distances. It is
in complete contradiction with the laws of nature, and all we know of
the changes our globe has undergone, to imagine that the animals have
actually adapted themselves to their various circumstances during
their migration, as this would be ascribing to physical influences as
much power as to the Creator himself.
And, again, the regular distribution, requiring precise laws, as we
find it does, cannot be attributed either to the voluntary migration
of animals, or to the influence of physical causes, when we see so
plainly that this distribution is in accordance with the geographical
distribution of animals and plants in former geological periods. But
about this presently. We will only add, that we cannot discover in the
Mosaic account anything to sustain such a view, nor even hints leading
to such a construction. What is said of animals and plants in the
first chapter of Genesis, what is mentioned of the preservation of
these animals and plants at the time of the deluge, relates chiefly to
organized beings placed about Adam and Eve, and those which their
progeny had domesticated, and which lived with them in closer
connection.
Let us now look at the results of geological investigations respecting
the origin of earlier races of animals and plants. It is
satisfactorily ascertained at present, that there have been many
distinct successive periods, during each of which large numbers of
animals and plants have been introduced upon the surface of our globe,
to live and multiply for a time, then to disappear and be replaced by
other kinds. Of such distinct periods, such successive creations, we
now know at least about a dozen, and there are ample indications that
the inhabitants of our globe have been successively changed at more
epochs than are yet fully ascertained. But whether the number of these
distinct successive creations be twelve or twenty, the fact stands in
full light and evidence, that animals and plants which lived during
the first period disappeared, either gradually or successively, to
make room for others, and this at often-repeated intervals; and that
the existence of animals and plants which live now is of but recent
origin, is equally well ascertained.
There is another series of phenomena, not less satisfactorily
established, which go to shew that the extent of dry land rising above
the surface of the ocean has neither been equally extensive at all
times, nor has it had the same outline at all periods. On the
contrary, we know that, early in the history of our globe, there has
been a period, when but few low groups of islands existed above the
surface of the ocean, which, through successive elevation and
depression, have gradually enlarged and modified the extent and form
of the mainland.
Again, in examining the remains of organized beings preserved in the
different strata constituting the solid crust of our globe, we find
that at each period, animals and plants were distributed in the ocean
and over the mainland in a particular manner, characteristic of every
great epoch. A closer uniformity in their distribution is found in the
earlier deposits, so much so that the oldest fossils discovered in the
southern extremity of Africa, on the eastern and southern shores of
New Holland, and in Van Diemen's Land, in North America, or in various
parts of Europe, are almost identical, or at least so nearly related,
that they resemble each other much more than the animals and plants
which at present live in the same countries; shewing that uniformity
in the aspect of the surface of the globe, as well as in the nature of
animals and plants, was at first the prevailing rule, and that,
whatever was the primitive region of these animals and plants, their
types occupied much more extensive districts than any race of living
beings during later periods. Are we to infer from this fact, that, at
that period, these animals and plants originated from one common
centre, and were distributed equally all over the globe? By no means.
Though slight, we find nevertheless such differences among them in
distant parts of the world as would rather sustain the view of an
adaptation in the earliest creations to more uniform circumstances,
than that of one centre of origin for all animals and plants of those
days. During later periods, indeed, we find from geological evidence
that large islands had been formed, more extensive tracts of land
elevated above the surface of the ocean, and the remains both of the
animals and plants derived from these different regions present
already marked differences when we compare them with each
other,--varieties similar to those which exist between the respective
continents at present, though perhaps less marked. Shall we here again
assume that animals and plants originated from another centre, or from
the same centre as those of former periods, to migrate over those
different parts of the world, through the sea as well as over land? It
is impossible to arrive at such a conclusion, when we consider the
distribution of fossil remains in the more recent geological deposits,
or in those strata which were formed during the latest geological
periods, immediately before the present creation. For we find in these
comparatively modern beds a distribution of fossil remains which
agrees in a most remarkable manner with the present geographical
arrangement of animals and plants. For instance, the fossils of modern
geological periods in New Holland are of the same types as most of the
animals now living there. Again, the recent fossils of Brazil belong
to the same families as those prevailing at present in Brazil; though,
in both cases, fossil species are distinct from living ones. If,
therefore, the organized beings of the recent geological periods had
arisen from one central point of distribution, to be dispersed and
finally to become confined to those countries where their remains are
found in a fossil condition, and if the animals now living had also
spread from a common origin over the same districts, and had then been
circumscribed within equally distinct limits, we should be led to the
unnatural supposition, that animals of two distinct creations,
differing specifically throughout, had taken the same lines of
migration, had assumed finally the same distribution, and had become
permanent in the same regions, without any other inducement for their
removal and final settlement than the mere necessity of covering more
extensive ground after they had become too numerous to remain any
longer together in one and the same district. This were to ascribe to
the animals themselves, or to the physical agents under which they
live, and by which they may be influenced, as much wisdom, as much
providential forethought, as is evinced throughout nature, both in the
distribution of animals, and in their special adaptation to particular
portions of the globe in which they are closely circumscribed at
present, and to which they were limited under similar circumstances
during those periods which preceded immediately the present
arrangement of things. Now these facts in themselves leave not the
shadow of a doubt in our mind, that animals were primitively created
all over the world, within those districts which they were naturally
to inhabit for a certain time. The next question is--were these
organized beings created in pairs, as is generally thought and
believed? The opinion, that all animals must be referred to one
single, primitive pair, is derived from evidence worthy of
consideration, no doubt, but the value of which may fairly be
questioned by naturalists; since this point, at least if we except
Adam and Eve, is entirely of human construction, and only assumed
because it is thought to shew a wise economy of means in the
established order of things which exists. It is supposed, that, if one
pair were sufficient, there is no reason why the Creator should have
introduced at one time a greater number of each kind, as economy of
means is always considered an indication of high wisdom. But are not
these human considerations? And if they are, and if we are entitled to
question their value, let us see how they answer the object which was
intended, namely, the peopling of the whole world with various races
of organized beings.
Whenever we consider the economy of nature, we observe great varieties
in the habits of different animals. There are, indeed, some which live
constantly in pairs, and which by nature are designed to perpetuate
their races in that way, and to spread generation after generation
over their natural boundaries, thus mated. But there are others to
which it is equally natural to live in herds or shoals, and which we
never find isolated. The idea of a pair of herrings, or of a pair of
buffaloes, is as contrary to the nature and habits of those
animals, as it is contrary to the nature of pines and birches to
grow singly, and to form forests in their isolation.
But we can go further. There are animals in which the number of
individuals of different sexes is naturally unequal, and among which
there are either constantly more males or constantly more females
born, as the result of their peculiar nature and habits in the
creation. A bee-hive never consists of a pair of bees; and never could
such a pair preserve the species, with their habits. For them it is
natural to have one female and many males devoted to it, and thousands
of neutral bees working for them. And this is the natural original
mode of existence among that species of animals, which it would be
utterly contrary to the laws of nature to consider as derived from a
single pair. There are a number of birds, on the contrary, in which
only a few males are universally found with many females, living
together in companies, such as the pheasants, and our domesticated
fowls. It were easy to multiply examples in order to shew that a
creation of all animals in pairs would have been contrary to their
very nature, as we observe it in all. To assume that they have changed
this nature would be to fall back upon the necessity of ascribing to
physical influences a power which they do not possess,--that of
producing changes in the very nature of organized beings, and of
modifying the primitive plan of the Creator.
Again, there are animals which, by nature, are impelled to feed upon
other animals. Was the primitive pair of lions to abstain from food
until the gazelles and other antelopes had sufficiently multiplied to
preserve their races from the persecution of these ferocious beasts?
Were all animals, and the innumerable tribes of ferocious fishes which
live upon smaller ones, to abstain from food till these had been
multiplied to a sufficient extent to secure their preservation? Or
were, perhaps, the carnivorous animals created only at a later period?
But we find them everywhere together. They constitute natural,
harmonious groups with the herbivorous tribes, both in the waters and
on land, preserving among each other such proportions as will maintain
for ages an undisturbed harmony in the creation.
Again, we find animals and plants occurring in distinct districts,
unconnected with each other, in such ways that it would seem almost
impossible for either to migrate from any point of their natural
circle of distribution over its whole surface. Have, for instance,
such animals as are found identical both in America and Europe been
created either in Europe or in America, and wandered from one of the
continents over to the other? Have those species which occur only in
the far north, and upon the higher summits of the Alps, been created
either in the Alps or in the north, and wandered from one place to the
other? We are at a loss for substantial arguments for believing that
either one or the other place has been the primitive location of such
animals, or for denying their simultaneous creation in both.
Evidence could be accumulated to shew, we will not say the
improbability only, but even the impossibility, of supposing that
animals and plants were created in single pairs, and assumed
afterwards their present distribution. But the facts mentioned will be
sufficient to introduce our argument, and from all we know of the laws
of nature and of the distribution of animals, we conclude that they
could neither originate from a single pair, nor upon a single spot.
And as for plants, we would ask naturalists whether it were not
superfluous to create more than a single stalk of most plants, as
vegetables, with a few exceptions, may multiply extensively from a
single stem. But if it is granted that animals could not originate
from a single pair, nor upon a single spot, what is the more natural
view to take of the subject?
Without entering fully into this question, we may as well state that
we have been gradually led to the conclusion, that most animals and
plants must have originated primitively over the whole extent of their
natural distribution. We mean to say that, for instance, lions, which
occur over almost the whole of Africa, over extensive parts of
Southern Asia, and were formerly found even over Asia-Minor and
Greece, must have originated primitively over the whole range of these
limits of their distribution. We are led to these conclusions by the
very fact, that the lions of the East Indies differ somewhat from
those of Northern Africa; these, again, differ from those of Senegal.
It seems more natural to suppose that they were thus distributed over
such wide districts, and endowed with particular characteristics in
each, than to assume that they constituted as many species; or to
believe that, created anywhere in this circle of distribution, they
have gradually been modified to their present differences in
consequence of their migration. We admit these differences to be
primitive and contemporaneous, from the fact, that there are other
animals of different genera extending over the same tracts of land
which have different representatives in each, circumscribed within
narrower bounds, and this particular combination in each special
district of the wider circle covered by the lion, seems, in our
opinion, the strongest argument in favour of the view, that the
particular districts of distribution have been primitively ascribed,
with definite limits, to each species. Why should the antelopes north
of the Cape of Good Hope differ from those of Arabia, or those of the
Senegal, or those of the Atlas, or those of the East Indies, if they
were not primitively adapted with their special modifications to those
districts, when we see the lion cover the whole range? And why should
the varieties we notice among the lions within these boundaries not be
primitive, though not constituting distinct species, when we see the
herbivorous species of the same genus differ from one district to
another? And why should the differences in that one species of lion be
the result of changes in its primitive character, arising from its
distribution into new districts, when we see that the antelopes are at
once fixed as distinct species over the same ground?
This argument cannot be fully appreciated by those who are not
extensively acquainted with natural history, but we may, perhaps, make
it plainer by alluding to some other similar facts. Our fresh waters
teem everywhere with animals and plants. Fishes and mollusca are among
the most prominent of their animals. Let us compare for a moment the
different species which occur in the Danube, in the Rhine, and in the
Rhone, three hydrographic basins entirely unconnected with each other
throughout their whole extent. They spring from the same mountain
chain, as we may take the Inn as the source of the Danube. These three
great rivers rise within a few miles of each other. Nevertheless, most
of their fishes differ, but there are some which are common to the
three. We find the pickerel,--the European pickerel, in the three
basins. The eel is also common to them all. One kind of trout occurs
in the three. But how strange the distribution of some others!--for
instance, the perches. In the Rhine we find _Perca fluviatilis_, and
_Acerina cernua_; in the Rhone, _Perca fluviatilis_, and _Aspro
vulgaris_; in the Danube, _Perca vulgaris_, _Lucio-perca Sandra_,
_Acerina cernua_, _A. Schraitzer_, _Aspro vulgaris_, and _A. Zingel_.
If these animals had not originated in these rivers separately, why
should not such closely-allied species, some of which occur in the
three basins, have all spread equally into them? and if they
originated in the separate basins, we have within close limits a
multiple origin of the same species.
And that this multiple origin must be admitted as a fact is shewn by
the following further evidence. Among the carpes we find, for
instance, _Barbus_, _Gobio_, _Carpio_, common to the three. But the
Danube has three _Gobios_, whilst the others have but one, one of the
Danube being identical with the one of the other two rivers. The most
striking fact, however, occurs in the genus _Leuciscus_. _Leuciscus
dobula_ is common to the three; but in addition to it, the Danube has
several species which occur neither in the Rhine nor in the Rhone. The
basin of the Rhone, again, has several species which occur neither in
the Danube nor in the Rhine; and in the Rhine, there are species which
belong neither to the Rhone nor to the Danube. Now, we ask, could all
these species of _Leuciscus_ have been created in one of the
basins,--in the Danube for instance,--and have migrated in such a way,
that a certain number of the species should remain solely in the
Danube, while some others left the Danube altogether to settle finally
only in the Rhone, and others to settle only in the Rhine; that one
accompanying those species peculiar to the Rhone, remained in the
Danube with those species peculiar to it, and settled also in the
Rhone, with those species peculiar to that river, and also in the
Rhine with the species peculiar to the Rhine? And whether we assume
the Rhone as the primitive centre, instead of the Danube or the Rhine,
the argument holds equally good. We have one species common to the
three rivers, and several species peculiar to each, which could never
have migrated (if migration took place) in such a manner as to assume
their present combinations. But if, on the contrary, we suppose that
all the species originated in the rivers where they occur, then we
have again a multiple origin of that species which is common to the
three, for it were wonderful if that one alone had migrated, when they
are all so closely allied. Here, again, we arrive at the conclusion,
that the same species can have a multiple origin, in the same manner
as, from the considerations alluded to before, we have decided that
species do not originate from single pairs, but in their natural
proportion with the other species with which they live simultaneously
over the whole ground which they cover. And this is the view which we
take of the natural distribution of animals, that they originated
primitively over the whole extent of their natural distribution; that
they originated there, not in pairs, but in large numbers, in such
proportions as suits their natural mode of living, and the
preservation of species; and that the same species may have originated
in different unconnected parts of the more extensive circle of their
distribution. We are well aware that there are very many species which
are known to have spread beyond what we would call their natural
limits; species which did not occur in North America before the
settlement of the whites, that are now abundant here over very
extensive tracts of country; other species which have been introduced
from America into Europe, and also into other parts of the world, in
different ways. But these are exceptional facts; and, what is more
important, these changes in the primitive distribution of organised
beings, both animals and plants, have taken place under the influence
of man,--under the influence of a being acting not merely from natural
impulses, or under the pressure of physical causes, but moved by a
higher will. So that these apparent exceptions to the rule would only
go to confirm it; as, within the limits of these secondary changes, we
see a will acting, just as we consider that the primitive distribution
of all organized beings has been the result of the decrees of the
Creator, and not the result of mere natural influences.
Having thus led the way to what we would consider as a fairer ground
for investigating the natural geographical distribution of animals and
plants, let us now examine the natural lines which seem to regulate
this distribution. Nothing can be more striking to the observer than
the fact, that animals, though endowed with the power of locomotion,
remain within fixed bounds in their geographical distribution,
although an unbounded field for migration is open to them in all
directions, over land, through the air, and through the waters. And no
stronger argument can be introduced to shew that living beings are
endowed with their power of locomotion to keep within general
boundaries, rather than to spread extensively. There is another fact
which shews that animals are made to remain within these natural
limits. We would allude especially to the difficulty we experience
whenever we attempt to transport animals from their native country
into other countries, even if we secure for them as nearly as can be
the same conditions in which they used to live. Again, observe the
changes which animals undergo when they are once acclimatized to
countries different from their native land. There can be no more
striking evidence of this than the endless variety of our domestic
animals, and there is no subject which more requires a renewed and
careful investigation than this. We do not, however, feel competent to
introduce this point more fully to the notice of our readers. Some
facts bearing upon the question may best be mentioned in a reference
to the different animals which man has thus made subservient to his
social condition. We shall here allude only to the laws of
distribution of wild animals in their natural condition.
It has already been stated, that the present distribution of animals
agrees with the distribution of extinct types belonging to earlier
geological periods, so that the laws which regulate the geographical
distribution of animals seem to have been the same at all times,
though modified in accordance with the successive changes which the
animal kingdom has undergone from the earliest period of its creation
to the present day. The universal law is, that all animals are
circumscribed within definite limits. There is not one species which
is uniformly spread all over the globe, either among the aquatic races
or among the terrestrial ones. Of the special distribution of man, who
alone is found everywhere, we shall speak hereafter. The special
adaptation of animals to certain districts is not merely limited to
the individual species. We observe a similar adaptation among genera,
entire families, and even whole classes. For instance, all _Polypi_,
_Medusæ_, and _Echinoderms_, that is to say all _Radiata_, without
exception, are aquatic.[1] That large group of animals has not a
single terrestrial representative upon any point of the surface of the
globe; and during all periods of the history of our earth, we find
that they have always been limited to the liquid element. And they are
not only aquatic, they are chiefly marine, as but exceedingly few of
them are found in fresh waters. Among _Mollusca_ we find almost the
same adaptation. Their element also is the sea. The number of
fresh-water species is small, compared with that of marine types; and
we find terrestrial species in only one of their classes. In former
periods, also, _Mollusca_ were chiefly marine; fluviatile and
terrestrial types occurring only in more recent periods.
Footnote 1: The following statements have been strictly
considered, and are made in reference to a revised classification
of the animal kingdom, the details of which must, however, be
omitted here, as they would extend this article beyond our
allotted bounds.
With the _Articulata_, we find another state of things. Two of their
classes, the worms and _Crustacea_, are chiefly marine, or at least
aquatic, as we have a number of fresh-water worms, and some
fresh-water _Crustacea_. But insects are, for the most part, chiefly
terrestrial, feeding upon terrestrial plants, at least in their
full-grown condition; though a large number of these animals are
fluviatile, and even some marine, during their earlier periods of
life. In the _Vertebrata_, the adaptations are more diversified. Only
one class of these animals is entirely aquatic--the fishes; and the
number of the marine species is far greater than that of the
fresh-water kinds. Among reptiles there are many which are aquatic,
either throughout life, or through the earlier period of their
existence. But, as if animal life rose to higher organization, as it
leaves the ocean to inhabit dry land or fresh waters, we find that the
greater number of the aquatic reptiles are fluviatile, and but a few
marine. This fact agrees wonderfully with the natural gradation of the
classes already mentioned. The lower type of animals, the _Radiata_,
is almost exclusively marine. Among _Mollusca_, we have a greater
number of marine types, a large number of fluviatile species, and
fewer terrestrial, and these are the highest in their class. Again,
among _Articulata_, the lower classes, worms and _Crustacea_, are
marine, or at least fluviatile, whilst the highest class, that of
insects, is chiefly terrestrial or fluviatile, during the earlier
periods of their growth. Among the _Vertebrata_ we see the lowest
form, that of fishes, entirely aquatic, and the same rule applies
partially to the reptiles; but as the class rises, the number of the
fluviatile species is greater than that of the marine types. Next,
among birds, which by their structure are exclusively adapted to live
in the atmospheric air, we find the larger number to be terrestrial,
and only the lower ones to live upon water, or dive occasionally into
it, always seeking the surface, however, to breathe and to perform
their most important vital functions. It is, nevertheless, not a
little strange, that this class should by nature be adapted to rise
into the air, just as if the first tendency towards liberating them
from the aquatic element had been carried to an excess, and gave them
a relation to the earth which no other class, as a whole, holds to
that degree, except, perhaps, the insects, which are placed among the
_Articulata_ in the same relation to the lower classes and the natural
element, which the class of birds maintains among _Vertebrata_. The
highest class of _Vertebrata_ affords us examples of these three modes
of adaptation, the lowest of these being entirely aquatic, and even
absolutely marine; next, we have fluviatile types of the large
terrestrial mammalia, in the family of _Manatees_, again, a swimming
family among Carnivora, another flying, most of them however walking
upon their four extremities on solid ground, but at the head of all,
man, standing upright, to look freely upwards, and to contemplate the
whole universe.
This wonderful adaptation of the whole range of animals, as it exists
at present, shews the most intimate connection with the order of
succession of animals in former geological periods. The four great
types, _Radiata_, _Mollusca_, _Articulata_, and _Vertebrata_, were
introduced at the beginning simultaneously. However, the earliest
representatives of these great types were all aquatic. We find in the
lowest beds which contain fossils, _Polypi_, together with
star-fishes, bivalve shells, univalves, chambered shells, cases of
worms, and _Crustacea_, being representatives of at least seven out of
nine classes of invertebrate animals, if we are not allowed to suppose
that _Medusæ_ existed also, and if insects were still wanting for a
time. But, in addition to these, fishes among _Vertebrata_ are
introduced, but fishes only, all of which are exclusively marine. At a
somewhat later period insects come in. We find next reptiles in
addition to fishes--the lower classes, or invertebrates, continuing to
be represented through all subsequent epochs, but by species changing
gradually at each period, as all classes do after they have been once
introduced. The first representatives among reptiles are marine, next
huge terrestrial ones, some, perhaps, flying types, and with them, and
perhaps even before them, birds, allied to the wading tribes: still
later, _Mammalia_, beginning again with marine and huge terrestrial
types, followed by the higher quadrupeds; and, last only, Man,--at the
head of the creation, in time as well as in eminence, by structure,
intelligence, and moral endowments.
Besides the general adaptation of animals to the surrounding media,
there is a more special adaptation, which seems not less important,
though it is perhaps less striking. Animals, as well as plants, do not
live equally at all depths of the ocean, or at all heights above its
surface. There must be a deep influence upon the geographical
distribution of animals in a vertical direction derived from
atmospheric pressure above the surface of the waters, and from the
pressure of the water itself at greater and greater depths,--the level
of the ocean, or a small elevation above its surface, or a shallow
depth under its surface, being the field of the most extensive and
intensive development of animal life. And it is not a little
remarkable that in the same classes we should find lower types at
greater depths in the ocean, and also lower types at greater heights
above. We will quote a few examples, to shew how much we may expect
from investigations pursued in this direction, for at present we have
but little information which can aid us in ascertaining the
relationship between atmospheric and hydrostatic pressure and the
energies of animal life.