have geological formations in progress. Not only would volcanoes belch
forth their liquid lavas and their stones and ashes, but the waves and
currents of the ocean and the rains and streams on the land, with the
ceaseless decomposing action of the carbonic acid of the atmosphere,
would be piling up mud, sand, and pebbles in the sea. There might even
be some formation of limestone taking place where springs charged
with bicarbonate of lime were oozing out on the land or the bottom of
the waters. But in such a world all the carbon would be in the state
of carbonic acid, and all the limestone would either be diffused in
small quantities through various rocks or in limited local beds, or
in solution, perhaps as chloride of calcium, in the sea. Dr. Hunt has
given chemical grounds for supposing that the most ancient seas were
largely supplied with this very soluble salt, instead of the chloride
of sodium, or common salt, which now prevails in the sea-water.
Where in such a world would life be introduced? on the land or in the
waters? All scientific probability would say in the latter. The ocean
is now vastly more populous than the land. The waters alone afford
the conditions necessary at once for the most minute and the grandest
organisms, at once for the simplest and for others of the most complex
character. Especially do they afford the best conditions for those
animals which subsist in complex communities, and which aggregate large
quantities of mineral matter in their skeletons. So true is this that
up to the present time all the species of Protozoa and of the animals
most nearly allied to them are aquatic. Even in the waters, however,
plant life, though possibly in very simple forms, must precede the
animal.
Let humble plants, then, be introduced in the waters, and they would
at once begin to use the solar light for the purpose of decomposing
carbonic acid, and forming carbon compounds which had not before
existed, and which independently of vegetable life would never have
existed. At the same time lime and other mineral substances present in
the sea-water would be fixed in the tissues of these plants, either
in a minute state of division, as little grains or Coccoliths, or in
more solid masses like those of the Corallines and Nullipores. In this
way a beginning of limestone formation might be made, and quantities
of carbonaceous and bituminous matter, resulting from the decay of
marine plants, might accumulate in the sea-bottom. The plants have
collected stores of organic matter, and their minute germs, along
with microscopic species, are floating everywhere in the sea. Nay,
there may be abundant examples of those Amœba-like germs of aquatic
plants, simulating for a time the life of the animal, and then
returning into the circle of vegetable life. In these some might see
precursors of the Protozoa, though they are probably rather prophetic
analogues than blood relations. The plant has fulfilled its function
as far as the waters are concerned, and now arises the opportunity
for the animal. In what form shall it appear? Many of its higher
forms, those which depend upon animal food or on the more complex
plants for subsistence, would obviously be unsuitable. Further, the
sea-water is still too much saturated with saline matter to be fit
for the higher animals of the waters. Still further, there may be a
residue of internal heat forbidding coolness, and that solution of free
oxygen which is an essential condition of existence to most of the
modern animals.[46] Something must be found suitable for this saline,
imperfectly oxygenated, tepid sea. Something too is wanted that can aid
in introducing conditions more favourable to higher life in the future.
Our experience of the modern world shows us that all these conditions
can be better fulfilled by the Protozoa than by any other creatures.
They can live now equally in those great depths of ocean where the
conditions are most unfavourable to other forms of life, and in tepid
unhealthy pools overstocked with vegetable matter in a state of
putridity. They form a most suitable basis for higher forms of life.
They have remarkable powers of removing mineral matters from the waters
and of fixing them in solid forms. So in the fitness of things Eozoon
is just what we need, and after it has spread itself over the mud and
rock of the primeval seas, and built up extensive reefs therein, other
animals may be introduced capable of feeding on it, or of sheltering
themselves in its stony masses, and thus we have the appropriate dawn
of animal life.
[Footnote 46: It has been assumed that any temperature over 120°
Fahrenheit would be incompatible with ordinary aquatic life. Still such
life is at least possible in some form up to 200°.]
But what are we to say of the cause of this new series of facts, so
wonderfully superimposed upon the merely vegetable and mineral? Must
it remain to us as an act of creation, or was it derived from some
pre-existing matter in which it had been potentially present ? Science
fails to inform us, but conjectural "phylogeny" steps in and takes its
place. Haeckel, one of the prophets of this new philosophy, waves his
magic wand, and simple masses of sarcode spring from inorganic matter,
and form diffused sheets of sea-slime, from which are in time separated
distinct Amœboid and Foraminiferal forms. Experience, however, gives us
no facts whereon to build this supposition, and it remains neither more
nor less scientific or certain than that old fancy of the Egyptians,
which derived animals from the fertile mud of the Nile.
If we fail to learn anything of the origin of Eozoon, and if its
life-processes are just as inscrutable as those of higher creatures,
we can at least inquire as to its history in geological time. In this
respect we find in the first place that the Protozoa have not had
a monopoly in their profession of accumulators of calcareous rock.
Originated by Eozoon in the old Laurentian time, this process has
been proceeding throughout the geological ages; and while Protozoa,
equally simple with the great prototype of the race, have been and
are continuing its function, and producing new limestones in every
geological period, and so adding to the volume of the successive
formations, new workers of higher grades have been introduced, capable
of enjoying higher forms of animal activity, and equally of labouring
at the great task of continent-building; of existing, too, in seas
less rich in mineral substances than those of the Eozoic time, and for
that very reason better suited to higher and more skilled artists.
It is to be observed in connection with this, that as the work of
the Foraminifers has thus been assumed by others, their size and
importance have diminished, and the grander forms of more recent times
have some of them been fain to build up their hard parts of cemented
sand instead of limestone.
But we further find that, while the first though not the only organic
gatherers of limestone from the ocean waters, they have had to do, not
merely with the formation of calcareous sediments, but also with that
of silicious deposits. The greenish silicate called glauconite, or
green-sand, is found to be associated with much of the foraminiferal
slime now accumulating in the ocean, and also with the older deposits
of this kind now consolidated in chalks and similar rocks. This name
glauconite is, as Dr. Hunt has shown, employed to designate not only
the hydrous silicate of iron and potash, which perhaps has the best
right to it, but also compounds which contain in addition large
percentages of alumina, or magnesia, or both; and one glauconite from
the Tertiary limestones near Paris is said to be a true serpentine,
or hydrous silicate of magnesia.[47] Now the association of such
substances with Foraminifera is not purely accidental. Just as a
fragment of decaying wood, imbedded in sediment, has the power of
decomposing soluble silicates carried to it by water, and parting with
its carbon in the form of carbonic acid, in exchange for the silica,
and thus replacing, particle by particle, the carbon of the wood with
silicon, so that at length it becomes petrified into a flinty mass, so
the sarcode of a Foraminifer can in like manner abstract silica from
the surrounding water or water-soaked sediment. From some peculiarity
in the conditions of the case, however, our Protozoon usually becomes
petrified with a hydrous silicate instead of with pure silica. The
favourable conditions presented by the deep sea for the combination
of silica with bases, as indicated in the reports of the _Challenger_
already referred to, may perhaps account in part for this. But whatever
the cause, it is usual to find fossil Foraminifera with their sarcode
replaced by such material. We also find beds of glauconite retaining
the forms of Foraminifera, while the calcareous tests of these have
been removed, apparently by acid waters.
[Footnote 47: Berthier, quoted by Hunt.]
One consideration which, though conjectural, deserves notice, is
connected with the food of these humble animals. They are known to feed
to a large extent on minute plants, the Diatoms, and other organisms
having silica in their skeletons or cell-walls, and consequently
soluble silicates in their juices. The silicious matter contained
in these organisms is not wanted by the Foraminifera for their own
skeletons, and will therefore be voided by them as an excrementitious
matter. In this way, where Foraminifera greatly abound, there may be
a large production of soluble silica and silicates, in a condition
ready to enter into new and insoluble compounds, and to fill the
cavities and pores of dead shells. Thus glauconite and even serpentine
may, in a certain sense, be a sort of foraminiferal coprolitic matter
or excrement. Of course it is not necessary to suppose that this is
the only source of such materials. They may be formed in other ways,
and especially by the disintegration of volcanic ashes and lapilli
in the sea-bottom; but I suggest this as at least a possible link of
connection.
Whether or not the conjecture last mentioned has any validity, there is
another and most curious bond of connection between oceanic Protozoa
and silicious deposits. Professor Wyville Thompson reports from the
_Challenger_ soundings, that in certain areas of the South Pacific
the ordinary foraminiferal ooze is replaced by a peculiar red clay,
which he attributes to the action of water laden with carbonic
acid, in removing all the lime, and leaving this red mud as a sort
of ash, composed of silica, alumina, and iron oxide. Now this is in
all probability a product of the decomposition and oxidation of the
glauconitic matter contained in the ooze. Thus we learn that when
areas on which calcareous deposits have been accumulated by Protozoa
are invaded by cold arctic or antarctic waters charged with carbonic
acid, the carbonate of lime may be removed, and the glauconite left, or
even the latter may be decomposed, leaving silicious, aluminous, and
other deposits, which may be quite destitute of any organic structures,
or retain only such remnants of them as have been accidentally or by
their more resisting character protected from destruction.[48] In this
way it may be possible that many silicious rocks of the Laurentian
and Primordial ages, which now show no trace of organization, may be
indirectly products of the action of life. In any case it seems plain
that beds of green-sand and similar hydrous silicates may be the
residue of thick deposits of foraminiferal limestone or chalky matter,
and that these silicates may in their turn be oxidized and decomposed,
leaving beds of apparently inorganic clay. Such beds may finally be
consolidated and rendered crystalline by metamorphism, and thus a
great variety of silicated rocks may result, retaining little or no
indication of any connection with the agency of life. We can scarcely
yet conjecture the amount of light which these new facts may eventually
throw on the serpentine and other rocks of the Eozoic age. In the
meantime they open up a noble field to chemists and microscopists.
[Footnote 48: The "red chalk" of Antrim, and that of Speeton, contain
arenaceous Foraminifera and silicious casts of their shells, apparently
different from typical glauconite, and the extremely fine ferruginous
and argillaceous sediment of these chalks may well be decomposed
glauconitic matter like that of the South Pacific. I have found these
beds, the hard limestones of the French Neocomian, and the altered
green-sands of the Alps, very instructive for comparison with the
Laurentian limestones; and they well deserve study by all interested in
such subjects.]
When the marvellous results of recent deep-sea dredgings were first
made known, and it was found that chalky foraminiferal earth is yet
accumulating in the Atlantic, with sponges and sea-urchins resembling
in many respects those whose remains exist in the chalk, the fact was
expressed by the statement that we still live in the chalk period.
Thus stated, the conclusion is scarcely correct. We do not live in the
chalk period, but the conditions of the chalk period still exist in the
deep sea. We may say more than this. To some extent the conditions of
the Laurentian period still exist in the sea, except in so far as they
have been removed by the action of the Foraminifera and other limestone
builders. To those who can realize the enormous lapse of time involved
in the geological history of the earth, this conveys an impression
almost of eternity in the existence of this oldest of all the families
of the animal kingdom.
We are still more deeply impressed with this when we bring into view
the great physical changes which have occurred since the dawn of life.
When we consider that the skeletons of Eozoon contribute to form the
oldest hills of our continents; that they have been sealed up in solid
marble, and that they are associated with hard crystalline rocks
contorted in the most fantastic manner; that these rocks have, almost
from the beginning of geological time, been undergoing waste to supply
the material of new formations; that they have witnessed innumerable
subsidences and elevations of the continents; and that the greatest
mountain chains of the earth have been built up from the sea since
Eozoon began to exist,--we acquire a most profound impression of the
persistence of the lower forms of animal life, and know that mountains
may be removed and continents swept away and replaced, before the least
of the humble gelatinous Protozoa can finally perish. Life may be a
fleeting thing in the individual, but as handed down through successive
generations of beings, and as a constant animating power in successive
organisms, it appears, like its Creator, eternal.
This leads to another and very serious question. How long did lineal
descendants of Eozoon exist, and do they still exist ? We may for
the present consider this question apart from ideas of derivation
and elevation into higher planes of existence of which, in point of
fact, we have no actual evidence. Eozoon as a species and even as a
genus may cease to exist with the Eozoic age, and we have no proof
that any succeeding forms of Protozoa are its modified descendants.
Whatever the causes which produced the earliest Protozoan, they may
have continued more or less to be operative in succeeding ages. As far
as their structures inform us, they may as much claim to be original
creations as Eozoon itself. Still descendants of Eozoon may have
continued to exist, though we have not yet met with them. I should not
be surprised to hear of a veritable specimen being some day dredged
alive in the Atlantic or the Pacific. It is also to be observed that
in animals so simple as Eozoon many varieties may appear, widely
different from the original. In these the general form and habit of
life are the most likely things to change, the minute structures much
less so. We need not, therefore, be surprised to find its descendants
diminishing in size or altering in general form, while the characters
of the fine tubulation and of the canal system would remain. We need
not wonder if any sessile Foraminifer of the Nummuline group should
prove to be a descendant of Eozoon. It would be less likely that a
Sponge or a Foraminifer of the Rotaline type should originate from
it. If one could only secure a succession of deep-sea limestones
with Foraminifers, extending all the way from the Laurentian to the
present time, I can imagine nothing more interesting than to compare
the whole series, with the view of ascertaining the limits of descent
with variation, and the points where new forms are introduced. We have
not yet such a series, but it may be obtained; and as Foraminifera
are eminently cosmopolitan, occurring over vastly wide areas of
sea-bottom, and are very variable, they would afford a better test of
theories of derivation than any that can be obtained from the more
locally distributed and less variable animals of higher grade. I was
much struck with this recently, in examining a series of Foraminifera
from the Cretaceous of Manitoba, and comparing them with the varietal
forms of the same species in the interior of Nebraska, 500 miles to
the south, and with those of the English chalk and of the modern seas.
In all these different times and places we had the same species. In
all they existed under so many varietal forms passing into each other,
that in former times every species had been multiplied into several.
Yet in all, the identical varietal forms were repeated with the most
minute markings alike. Here were at once constancy the most remarkable
and variations the most extensive. If we dwell on the one to the
exclusion of the other, we reach only one-sided conclusions, imperfect
and unsatisfactory. By taking both in connection we can alone realize
the full significance of the facts. We cannot yet obtain such series
for all geological time; but it may even now be worth while to inquire,
What do we know as to any modification in the case of the primeval
Foraminifers, whether with reference to the derivation from them of
other Protozoa or of higher forms of life?
There is no link whatever in geological fact to connect Eozoon with any
of the Mollusks, Radiates, or Crustaceans of the succeeding Palæozoic.
What may be discovered in the future we cannot conjecture; but at
present these stand before us as distinct creations. It would, of
course, be more probable that Eozoon should be the ancestor of some
of the Foraminifera of the Primordial age, but strangely enough it is
very dissimilar from all these except Cryptozoon; and here, as already
stated, the evidence of minute structure fails to a great extent, and
Eozoon Bavaricum of the Huronian age scarcely helps to bridge over the
gap which yawns in our imperfect geological record. Of actual facts,
therefore, we have none; and those evolutionists who have regarded the
dawn-animal as an evidence in their favour, have been obliged to have
recourse to supposition and assumption.
Taking the ground of the derivationist, it is convenient to assume
(1) that Eozoon was either the first or nearly the first of animals,
and that, being a Protozoan of simple structure, it constitutes an
appropriate beginning of life; (2) that it originated from some
unexplained change in the protoplasmic or albuminous matter of some
humble plant, or directly from inorganic matter, or at least was
descended from some creature only a little more simple which had
being in this way; (3) that it had in itself unlimited capacities
for variation and also for extension in time; (4) that it tended to
multiply rapidly, and at last so to occupy the ocean that a struggle
for existence arose; (5) that though at first, from the very nature
of its origin, adapted to the conditions of the world, yet as these
conditions became altered by physical changes, it was induced to
accommodate itself to them, and so to pass into new species and genera,
until at last it appeared in entirely new types in the Cambrian fauna.
These assumptions are, with the exception of the first two, merely
the application to Eozoon of what have been called the Darwinian laws
of multiplication, of limited population, of variation, of change
of physical conditions, and of equilibrium of nature. If otherwise
proved, and shown to be applicable to creatures like Eozoon, of course
we must apply them to it; but in so far as that creature itself is
concerned they are incapable of proof, and some of them contrary to
such evidence as we have. We have, for example, no connecting link
between Eozoon and any form of vegetable life. Its structures are such
as to enable us at once to assign it to the animal kingdom, and if we
seek for connecting links between the lower animals and plants, we have
to look for them in the modern waters. We have no reason to conclude
that Eozoon could multiply so rapidly as to fill all the stations
suitable for it, and to commence a struggle for existence. On the
contrary, after the lapse of untold ages the conditions for the life of
Foraminifers still exist over two-thirds of the surface of the earth.
In regard to variation, we have, it is true, evidence of the wide range
of varieties of species in Protozoa, within the limits of the group,
but none whatever of any tendency to pass into other groups. Nor can
it be proved that the conditions of the ocean were so different in
Cambrian or Silurian times as to preclude the continued and comfortable
existence of Eozoon. New creatures came in which superseded it, and
new conditions more favourable in proportion to these new creatures;
but neither the new creatures nor the new conditions were necessarily
or probably connected with Eozoon, any farther than that it may
have served newer tribes of animals for food, and may have rid the
sea of some of its superfluous lime in their interest. In short, the
hypothesis of evolution will explain the derivation of other animals
from Eozoon if we adopt its assumptions, just as it will in that case
explain anything else; but the assumptions are improbable, and contrary
to such facts as we know.
Eozoon itself, however, bears some negative though damaging testimony
against evolution, and I take the liberty of repeating here a summary
of its imaginary autobiography:--"I, Eozoon Canadense, being a creature
of low organization and intelligence, and of practical turn, am no
theorist, but have a lively appreciation of such facts as I am able
to perceive. I found myself growing upon the sea-bottom, and know not
whence I came. I grew and flourished for ages, and found no let or
hindrance to my expansion, and abundance of food was always floated
to me without my having to go in search of it. At length a change
came. Certain creatures with hard snouts and jaws began to prey on
me. Whence they came I know not; I cannot think that they came from
the germs which I had dispersed so abundantly throughout the ocean.
Unfortunately, just at the same time lime became a little less abundant
in the waters, perhaps because of the great demands I myself had made,
and thus it was not so easy as before to produce a thick supplemental
skeleton for defence. So I had to give way. I have done my best to
avoid extinction; but it is clear that I must at length be overcome,
and must either disappear or subside into a humbler condition, and that
other creatures better provided for the new conditions of the world
must take my place." In such terms we may suppose that this patriarch
of the seas might tell his history, and mourn his destiny, though he
might also congratulate himself on having in an honest way done his
duty and fulfilled his function in the world, leaving it to other and
perhaps wiser creatures to dispute as to his origin and fate, while,
much less perfectly fulfilling the ends of their own existence.