THE DAWN-ANIMAL AS A TEACHER IN SCIENCE.
The thoughts suggested to the philosophical naturalist by the
contemplation of the dawn of life on our planet are necessarily many
and exciting, and the subject has in it the materials for enabling the
general reader better to judge of some of the theories of the origin of
life agitated in our time. In this respect our dawn-animal has scarcely
yet had justice; and we may not be able to render this in these pages.
Let us put it into the witness-box, however, and try to elicit its
testimony as to the beginnings of life.
Looking down from the elevation of our physiological and mental
superiority, it is difficult to realize the exact conditions in which
life exists in creatures so simple as the Protozoa. There may perhaps
be higher intelligences that find it equally difficult to realize how
life and reason can manifest themselves in such poor houses of clay
as those we inhabit. But placing ourselves near to these creatures,
and entering as it were into sympathy with them, we can understand
something of their powers and feelings. In the first place it is plain
that they can vigorously, if roughly, exercise those mechanical,
chemical, and vegetative powers of life which are characteristic of
the animal. They can seize, swallow, digest, and assimilate food; and,
employing its albuminous parts in nourishing their tissues, can burn
away the rest in processes akin to our respiration, or reject it from
their system. Like us, they can subsist only on food which the plant
has previously produced; for in this world, from the beginning of time,
the plant has been the only organism which could use the solar light
and heat as forces to enable it to turn the dead elements of matter
into living, growing tissues, and into organic compounds capable of
nourishing the animal. Like us, the Protozoa expend the food which
they have assimilated in the production of animal force, and in doing
so cause it to be oxidized, or burnt away, and resolved again into
dead matter. It is true that we have much more complicated apparatus
for performing these functions, but it does not follow that this gives
us much real superiority, except relatively to the more difficult
conditions of our existence. The gourmand who enjoys his dinner may
have no more pleasure in the act than the Amœba which swallows a
Diatom; and for all that the man knows of the subsequent processes to
which the food is subjected, his interior might be a mass of jelly,
with extemporised vacuoles, like that of his humble fellow-animal. The
workman or the athlete has bones and muscles of vastly complicated
structure, but to him the muscular act is as simple and unconscious a
process as the sending out of a pseudopod to a Protozoon. The clay is
after all the same, and there may be as much credit to the artist in
making a simple organism with varied powers, as a more complex frame
for doing nicer work. It is a weakness of humanity to plume itself on
advantages not of its own making, and to treat its superior gifts as
if they were the result of its own endeavours. The truculent traveller
who illustrated his boast of superiority over the Indian by comparing
his rifle with the bow and arrows of the savage, was well answered by
the question, "Can you make a rifle?" and when he had to answer, "No,"
by the rejoinder, "Then I am at least better than you, for I can make
my bow and arrows." The Amœba or the Eozoon is probably no more than we
its own creator; but if it could produce itself out of vegetable matter
or out of inorganic substances, it might claim in so far a higher
place in the scale of being than we; and as it is, it can assert equal
powers of digestion, assimilation, and motion, with much less of bodily
mechanism.
In order that we may feel, a complicated apparatus of nerves and
brain-cells has to be constructed and set to work; but the Protozoon,
without any distinct brain, is all brain, and its sensation is simply
direct. Thus vision in these creatures is probably performed in a rough
way by any part of their transparent bodies, and taste and smell are no
doubt in the same case. Whether they have any perception of sound as
distinct from the mere vibrations ascertained by touch, we do not know.
Here also we are not far removed above the Protozoa, especially those
of us to whom touch, seeing, and hearing are mere feelings, without
thought or knowledge of the apparatus employed. We might so far as
well be Amœbas. As we rise higher we meet with more differences. Yet
it is evident that our gelatinous fellow-being can feel pain, dread
danger, desire possessions, enjoy pleasure, and in a simple unconscious
way entertain many of the appetites and passions that affect ourselves.
The wonder is that with so little of organization it can do so much.
Yet, perhaps, life can manifest itself in a broader and more intense
way where there is little organization; and a highly strung and
complex organism is not so much a necessary condition of a higher life
as a mere means of better adapting it to its present surroundings.
Those philosophies which identify the thinking mind with the material
organism, must seem outrageous blunders to an Amœba on the one hand, or
to an angel on the other, could either be enabled to understand them;
which, however, is not very probable, as they are too intimately bound
up with the mere prejudices incident to the present condition of our
humanity. In any case the Protozoa teach us how much of animal function
may be fulfilled by a very simple organism, and warn us against the
fallacy that creatures of this simple structure are necessarily nearer
to inorganic matter, and more easily developed from it than beings of
more complex mould.
A similar lesson is taught by the complexity of their skeletons.
We speak in a crude unscientific way of these animals accumulating
calcareous matter, and building up reefs of limestone. We must,
however, bear in mind that they are as dependent on their food for
the materials of their skeletons as we are, and that their crusts
grow in the interior of the sarcode just as our bones do within our
bodies. The provision even for nourishing the interior of the skeleton
by tubuli and canals is in principle similar to that involved in the
Haversian canals, cells, and canalicules of bone. The Amœba of course
knows neither more nor less of this than the average Englishman.
It is altogether a matter of unconscious growth. The process in
the Protozoa strikes some minds, however, as the more wonderful of
the two. It is, says an eminent modern physiologist, a matter of
"profound significance" that this "particle of jelly [the sarcode
of a Foraminifer] is capable of guiding physical forces in such a
manner as to give rise to these exquisite and almost mathematically
arranged structures." Respecting the structures themselves there is no
exaggeration in this. No arch or dome framed by human skill is more
perfect in beauty or in the realization of mechanical ideas than the
tests of some Foraminifera, and none is so complete and wonderful in
its internal structure. The particle of jelly, however, is a figure of
speech. The body of the humblest Foraminifer is much more than this.
It is an organism with divers parts, as we have already seen in a
previous chapter, and it is endowed with the mysterious forces of life
which in it guide the physical forces, just as they do in building
up phosphate of lime in our bones, or indeed just as the will of the
architect does in building a palace. The profound significance which
this has, reaches beyond the domain of the physical and vital, even to
the spiritual. It clings to all our conceptions of living things: quite
as much, for example, to the evolution of an animal with all its parts
from a one-celled germ, or to the connection of brain-cells with the
manifestations of intelligence. Viewed in this way, we may share with
the author of the sentence I have quoted his feeling of veneration in
the presence of this great wonder of animal life, "burning, and not
consumed," nay, building up, and that in many and beautiful forms. We
may realize it most of all in the presence of the organism which was
perhaps the first to manifest on our planet these marvellous powers.
We must, however, here also, beware of that credulity which makes too
many thinkers limit their conceptions altogether to physical force
in matters of this kind. The merely materialistic physiologist is
really in no better position than the savage who quails before the
thunderstorm, or rejoices in the solar warmth, and seeing no force or
power beyond, fancies himself in the immediate presence of his God. In
Eozoon we must discern not only a mass of jelly, but a being endowed
with that higher vital force which surpasses vegetable life and also
physical and chemical forces; and in this animal energy we must see an
emanation from a Will higher than our own, ruling vitality itself; and
this not merely to the end of constructing the skeleton of a Protozoon,
but of elaborating all the wonderful developments of life that were to
follow in succeeding ages, and with reference to which the production
and growth of this creature were initial steps. It is this mystery of
design which really constitutes the "profound significance" of the
foraminiferal skeleton.
Another phenomenon of animality forced upon our notice by the Protozoa
is that of the conditions of life in animals not individual, as we
are, but aggregative and cumulative in indefinite masses. What, for
instance, the relations to each other of the Polyps, growing together
in a coral mass, of the separate parts of a Sponge, or the separate
cells of a Foraminifer, or of the sarcode mass of an indefinitely
spread out Stromatopora or Bathybius. In the case of the Polyps, we
may believe that there is special sensation in the tentacles and
oral opening of each individual, and that each may experience hunger
when in want, or satisfaction when it is filled with food, and that
injuries to one part of the mass may indirectly affect other parts,
but that the nutrition of the whole mass may be as much unfelt by the
individual Polyps as the processes going on in our own bones are by
us. So in the case of a large Sponge or Foraminifer, there may be some
special sensation in individual cells, pseudopods, or segments, and
the general sensation may be very limited, while unconscious living
powers pervade the whole. In this matter of aggregation of animals we
have thus various grades. The Foraminifers and Sponges present us with
the simplest of all, and that which most resembles the aggregation of
buds in the plant. The Polyps and complex Bryozoons present a higher
and more specialised type; and though the bilateral symmetry which
obtains in the higher animals is of a different nature, it still at
least reminds us of that multiplication of similar parts which we see
in the lower grades of being. It is worthy of notice here that the
lower animals which show aggregative tendencies present but imperfect
indications, or none at all, of bilateral symmetry. Their bodies, like
those of plants, are for the most part built up around a central axis,
or they show tendencies to spiral modes of growth.
It is this composite sort of life which is connected with the main
geological function of the Foraminifer. While active sensation,
appetite, and enjoyment pervade the pseudopods and external sarcode
of the mass, the hard skeleton common to the whole is growing within;
and in this way the calcareous matter is gradually removed from
the sea water, and built up in solid reefs, or in piles of loose
foraminiferal shells. Thus it is the aggregative or common life,
alike in Foraminifers as in Corals, that tends most powerfully to the
accumulation of calcareous matter; and those creatures whose life is
of this complex character are best suited to be world-builders, since
the result of their growth is not merely a cemetery of their osseous
remains, but a huge communistic edifice, to which multitudes of lives
have contributed, and in which successive generations take up their
abode on the remains of their ancestors. This process, so potent in
the progress of the earth's geological history, began, as far as we
know, with Eozoon.
Whether, then, in questioning our proto-foraminifer, we have reference
to the vital functions of its gelatinous sarcode, to the complexity and
beauty of its calcareous test, or to its capacity for effecting great
material results through the union of individuals, we perceive that we
have to do, not with a low condition of those powers which we designate
life, but with the manifestation of those powers through the means of a
simple organism; and this in a degree of perfection which we, from our
point of view, would have in the first instance supposed impossible.
If we imagine a world altogether destitute of life, we still might
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. Now arises the opportunity
for animal life. 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. 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.
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, the prophet 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.[BA] 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, which is a more dense kind of
animal matter than is usually supposed, 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, 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 BA: 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; 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.[BB] 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. When the recent deposits
discovered by the _Challenger_ dredgings shall have been more fully
examined, we may perhaps have the means of distinguishing such rocks,
and thus of still further enlarging our conceptions of the part played
by Protozoa in the drama of the earth's history. 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 oxidised 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 BB: 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. Eozoon as a species and
even as a genus may cease to exist with the Eozoic age, and we have no
evidence whatever that Archæocyathus, Stromatopora, or Receptaculites
are its modified descendants. 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 Primordial.
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 Stromatopora; 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 Primordial 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 its argument may be thus stated in what we may
imagine to be its own expressions:--"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.
Thus our dawn-animal has positively no story to tell as to his own
introduction or his transmutation into other forms of existence.
He leaves the mystery of creation where it was; but in connection
with the subsequent history of life we can learn from him a little
as to the laws which have governed the succession of animals in
geological time. First, we may learn that the plan of creation has been
progressive, that there has been an advance from the few, low, and
generalized types of the primæval ocean to the more numerous, higher,
and more specialized types of more recent times. Secondly, we learn
that the lower types, when first introduced, and before they were
subordinated to higher forms of life, existed in some of their grandest
modifications as to form and complexity, and that in succeeding ages,
when higher types were replacing them, they were subjected to decay and
degeneracy. Thirdly, we learn that while the species has a limited term
of existence in geological time, any grand type of animal existence,
like that of the Foraminifera or Sponges, for example, once introduced,
continues and finds throughout all the vicissitudes of the earth some
appropriate residence. Fourthly, as to the mode of introduction of new
types, or whether such creatures as Eozoon had any direct connection
with the subsequent introduction of mollusks, worms, or crustaceans, it
is altogether silent, nor can it predict anything as to the order or
manner of their introduction.
Had we been permitted to visit the Laurentian seas, and to study Eozoon
and its contemporary Protozoa when alive, it is plain that we could not
have foreseen or predicted from the consideration of such organisms
the future development of life. No amount of study of the prototypal
Foraminifer could have led us distinctly to the conception of even
a Sponge or a Polyp, much less of any of the higher animals. Why is
this? The answer is that the improvement into such higher types does
not take place by any change of the elementary sarcode, either in those
chemical, mechanical, or vital properties which we can study, but in
the adding to it of new structures. In the Sponge, which is perhaps
the nearest type of all, we have the movable pulsating cilium and true
animal cellular tissue, and along with this the spicular or fibrous
skeleton, these structures leading to an entire change in the mode of
life and subsistence. In the higher types of animals it is the same.
Even in the highest we have white blood-corpuscles and germinal matter,
which, in so far as we know, carry on no higher forms of life than
those of an Amœba; but they are now made subordinate to other kinds of
tissue, of great variety and complexity, which never have been observed
to arise out of the growth of any Protozoon. There would be only a very
few conceivable inferences which the highest finite intelligence could
deduce as to the development of future and higher animals. He might
infer that the foraminiferal sarcode, once introduced, might be the
substratum or foundation of other but unknown tissues in the higher
animals, and that the Protozoan type might continue to subsist side
by side with higher forms of living things as they were successively
introduced. He might also infer that the elevation of the animal
kingdom would take place with reference to those new properties of
sensation and voluntary motion in which the humblest animals diverge
from the life of the plant.
It is important that these points should be clearly before our minds,
because there has been current of late among naturalists a loose way
of writing with reference to them, which seems to have imposed on many
who are not naturalists. It has been said, for example, that such an
organism as Eozoon may include potentially all the structures and
functions of the higher animals, and that it is possible that we might
be able to infer or calculate all these with as much certainty as we
can calculate an eclipse or any other physical phenomenon. Now, there
is not only no foundation in fact for these assertions, but it is from
our present standpoint not conceivable that they can ever be realized.
The laws of inorganic matter give no data whence any _à priori_
deductions or calculations could be made as to the structure and
vital forces of the plant. The plant gives no data from which we can
calculate the functions of the animal. The Protozoon gives no data from
which we can calculate the specialties of the Mollusc, the Articulate,
or the Vertebrate. Nor unhappily do the present conditions of life of
themselves give us any sure grounds for predicting the new creations
that may be in store for our old planet. Those who think to build a
philosophy and even a religion on such data are mere dreamers, and have
no scientific basis for their dogmas. They are more blind guides than
our primæval Protozoon himself would be, in matters whose real solution
lies in the harmony of our own higher and immaterial nature with the
Being who is the author of all life--the Father "from whom every
family in heaven and earth is named."
While this work was going through the press, Lyell, the greatest
geological thinker of our time, passed away. In the preceding pages I
have refrained from quoting the many able geologists and biologists who
have publicly accepted the evidence of the animal nature of Eozoon as
sufficient, preferring to rest my case on its own merits rather than on
authority; but it is due to the great man whose loss we now mourn, to
say that, before the discovery of Eozoon, he had expressed on general
grounds his anticipation that fossils would be found in the rocks older
than the so-called Primordial Series, and that he at once admitted the
organic nature of Eozoon, and introduced it, as a fossil, into the
edition of his Elements of Geology published in the same year in which
it was described.
APPENDIX.
CHARACTERS OF LAURENTIAN AND HURONIAN PROTOZOA.
It may be useful to students to state the technical characters of
Eozoon, in addition to the more popular and general descriptions in the
preceding pages.
_Genus_ EOZOON.
Foraminiferal skeletons, with irregular and often confluent cells,
arranged in concentric and horizontal laminæ, or sometimes piled in an
acervuline manner. Septal orifices irregularly disposed. Proper wall
finely tubulated. Intermediate skeleton with branching canals.
Eozoon Canadense, _Dawson_.
In rounded masses or thick encrusting sheets, frequently of large
dimensions. Typical structure stromatoporoid, or with concentric
calcareous walls, frequently uniting with each other, and separating
flat chambers, more or less mammillated, and spreading into horizontal
lobes and small chamberlets; chambers often confluent and crossed by
irregular calcareous pillars connecting the opposite walls. Upper
part often composed of acervuline chambers of rounded forms. Proper
wall tubulated very finely. Intermediate skeleton largely developed,
especially at the lower part, and traversed by large canals, often
with smaller canals in their interstices. Lower laminæ and chambers
often three millimetres in thickness. Upper laminæ and chambers one
millimetre or less. Age Laurentian and perhaps Huronian.
_Var._ MINOR.--Supplemental skeleton wanting, except near the base, and
with very fine canals. Laminæ of sarcode much mammillated, thin, and
separated by very thin walls. Probably a depauperated variety.
_Var._ ACERVULINA.--In oval or rounded masses, wholly acervuline. Cells
rounded; intermediate skeleton absent or much reduced; cell-walls
tubulated. This may be a distinct species, but it closely resembles the
acervuline parts of the ordinary form.
Eozoon Bavaricum, _Gümbel_.
Composed of small acervuline chambers, separated by contorted walls,
and associated with broad plate-like chambers below. Large canals
in the thicker parts of the intermediate skeleton. Differs from _E.
Canadense_ in its smaller and more contorted chambers. Age probably
Huronian.
_Genus_ ARCHÆOSPHERINA.
A provisional genus, to include rounded solitary chambers, or
globigerine assemblages of such chambers, with the cell-wall
surrounding them tubulated as in Eozoon. They may be distinct
organisms, or gemmæ or detached fragments of Eozoon. Some of them
much resemble the bodies figured by Dr. Carpenter, as gemmæ or ova
and primitive chambers of Orbitolites. They are very abundant on some
of the strata surfaces of the limestone at Côte St. Pierre. Age Lower
Laurentian.
SYSTEMATIC POSITION OF EOZOON.
The unsettled condition of the classification of the Protozoa, and our
absolute ignorance of the animal matter of Eozoon, render it difficult
to make any statement on this subject more definite than the somewhat
vague intimations given in the text. My own views at present, based on
the study of recent and fossil forms, and of the writings of Carpenter,
Max Schultze, Carter, Wallich, Haeckel, and Clarepede, may be stated,
though with some diffidence, as follows:--
I. The class _Rhizopoda_ includes all the sarcodous animals whose only
external organs are pseudopodia, and is the lowest class in the animal
kingdom. Immediately above it are the classes of the Sponges and of the
flagellate and ciliate Infusoria, which rise from it like two diverging
branches.
II. The group of Rhizopods, as thus defined, includes three leading
_orders_, which, in descending grade, are as follows:--
(_a_) _Lobosa_, or Amœboid Rhizopods, including those with
distinct nucleus and pulsating vesicle, and thick lobulate
pseudopodia--naked, or in membranous coverings.
(_b_) _Radiolaria_, or Polycistius and their allies, including
those with thread-like pseudopodia, with or without a
nucleus, and with the skeleton, when present, silicious.
(_c_) _Reticularia_, or Foraminifera and their allies, including
those with thread-like and reticulating pseudopodia, with
granular matter instead of a nucleus, and with calcareous,
membranous, or arenaceous skeletons.
The place of _Eozoon_ will be in the lowest order, _Reticularia_.
III. The order _Reticularia_ may be farther divided into two
_sub-orders_, as follows:--
(_a_) _Perforata_--having calcareous skeletons penetrated with
pores.
(_b_) _Imperforata_--having calcareous, membranous, or arenaceous
skeletons, without pores.
The place of Eozoon will be in the higher sub-order, _Perforata_.
IV. The sub-order _Perforata_ includes three _families_--the
_Nummulinidæ_, _Globigerinidæ_, and _Lagemdæ_. Of these Carpenter
regards the Nummulinidæ as the highest in rank.
The place of Eozoon will be in the family _Nummulinidæ_, or between
this and the next family. This oldest known Protozoon would thus belong
to the highest family in the highest sub-order of the lowest class of
animals.
THE LATE SIR WILLIAM E. LOGAN.
When writing the dedication of this work, I little thought that the
eminent geologist and valued friend to whom it gave me so much pleasure
to tender this tribute of respect, would have passed away before its
publication. But so it is, and we have now to mourn, not only Lyell,
who so frankly accepted the evidence in favour of Eozoon, but Logan,
who so boldly from the first maintained its true nature as a fossil.
This boldness on his part is the more remarkable and impressive, from
the extreme caution by which he was characterized, and which induced
him to take the most scrupulous pains to verify every new fact before
committing himself to it. Though Sir William's early work in the Welsh
coal-fields, his organization and management of the Survey of Canada,
and his reducing to order for the first time all the widely extended
Palæozoic formations of that great country, must always constitute
leading elements in his reputation, I think that in nothing does he
deserve greater credit than in the skill and genius with which he
attacked the difficult problem of the Laurentian rocks, unravelled
their intricacies, and ascertained their true nature as sediments, and
the leading facts of their arrangement and distribution. The discovery
of Eozoon was one of the results of this great work; and it was the
firm conviction to which Sir William had attained of the sedimentary
character of the rocks, which rendered his mind open to the evidence of
these contained fossils, and induced him even to expect the discovery
of them.
This would not be the proper place to dwell on the general character
and work of Sir William Logan, but I cannot close without referring to
his untiring industry, his enthusiasm in the investigation of nature,
his cheerful and single-hearted disposition, his earnest public spirit
and patriotism--qualities which won for him the regard even of those
who could little appreciate the details of his work, and which did much
to enable him to attain to the success which he achieved.
INDEX.
Acervuline explained, 66.
Acervuline Variety of Eozoon, 135.
Aggregative Growth of Animals, 213.
Aker Limestone, 197.
Amity Limestone, 197.
Amœba described, 59.
Annelid Burrows, 133, 139.
Archæospherinæ, 137, 148.
Archæocyathus, 151.
Arisaig, Supposed Eozoon of, 140.
Bathybius, 65.
Bavaria, Eozoon of, 148.
Beginning of Life, 215.
Billings, Mr.,--referred to, 41;
on Archæocyathus, 151;
on Receptaculites, 163.
Calumet, Eozoon of, 38.
Calcarina, 74.
Calcite filling Tubes of Eozoon, 98.
Canal System of Eozoon, 40, 66, 107, 176, 181.
Carpenter--referred to, 41;
on Eozoon, 82;
Reply to Carter, 204.
Caunopora, 158.
Chrysotile Veins, 107, 180.
Chemistry of Eozoon, 199.
Coccoliths, 70.
Cœnostroma, 158.
Contemporaries of Eozoon, 127.
Côte St. Pierre, 20.
Derivation applied to Eozoon, 225.
Discovery of Eozoon, 35.
Eozoic Time, 7.
Eozoon,--Discovery of, 35;
Structure of, 65;
Growth of, 70;
Fragments of, 74;
Description of, 65, 77 (also Appendix);
Note on by Dr. Carpenter, 82;
Thickened Walls of, 66;
Preservation of, 100;
Pores filled with Calcite, 97, 109;
with Pyroxene, 108;
with Serpentine, 101;
with Dolomite, 109;
in Limestone, 110;
Defective Specimens of, 113;
how Mineralized, 102, 116;
its Contemporaries, 127;
Acervuline Variety of, 135;
Variety _Minor_ of, 135;
Acadianum, 140;
Bavaricum, 148;
Localities of, 166;
Harmony of with other Fossils, 171;
Summary of evidence relating to, 176.
Faulted Eozoon, 182.
Foraminifera, Notice of, 61.
Fossils, how Mineralized, 93.
Fusulina, 74.
Glauconite, 100, 125, 220.
Graphite of Laurentian, 18, 27.
Green-sand, 99.
Grenville, Eozoon of, 38.
Gümbel on Laurentian Fossils, 124;
on Eozoon Bavaricum, 141.
Hastings, Rocks of, 57.
History of Discovery of Eozoon, 35.
Honeyman, Dr., referred to, 140.
Hunt, Dr. Sterry, referred to, 35;
on Mineralization of Eozoon, 115;
on Silurian Fossils infiltrated with Silicates, 121;
on Minerals of the Laurentian, 123;
on Laurentian Life, 27;
his Reply to Objections, 199.
Huronian Rocks, 9.
Intermediate Skeleton, 64.
Iron Ores of Laurentian, 19.
Jones, Prof. T. Rupert, on Eozoon, 42.
King, Prof., his Objections, 184.
Labrador Feldspar, 13.
Laurentian Rocks, 7;
Fossils of, 130;
Graphite of, 18, 27;
Iron Ores of, 19;
Limestones of, 17.
Limestones, Laurentian, 17;
Silurian, 98.
Localities of Eozoon, 166.
Loftusia, 164.
Logan, Sir Wm., referred to, 36;
on Laurentian, 24;
on Nature of Eozoon, 37;
Geological Relations of Eozoon, 48;
on Additional Specimens of Eozoon, 52.
Loganite in Eozoon, 36, 102.
Lowe, Mr., referred to, 38.
Long Lake, Specimens from, 91.
Lyell, Sir C., on Eozoon, 234.
Madoc, Specimens from, 132.
Maps of Laurentian, 7, 16.
MacMullen, Mr., referred to, 37.
Metamorphism of Rocks, 13, 34.
Mineralization of Eozoon, 101;
of Fossils, 93;
Hunt on, 115.
Nicholson on Stromatopora, 165.
Nummulites, 73.
Nummuline Wall, 43, 65, 106, 176, 181.
Objections answered, 169, 188.
Parkeria, 164.
Petite Nation, 20, 43.
Pole Hill, Specimens from, 121.
Proper Wall, 43, 65, 106, 176, 181.
Preservation of Eozoon, 93.
Protozoa, their Nature, 59, 207.
Pseudomorphism, 200.
Pyroxene filling Eozoon, 108.
Red Clay of Pacific, 222.
Red Chalk, 222.
Reply to Objections, 167, 188.
Receptaculites, 162.
Robb, Mr., referred to, 120.
Rowney, Prof., Objections of, 184.
Serpentine mineralizing Eozoon, 102.
Silicates mineralizing Fossils, 100, 103, 121, 220.
Silurian Fossils infiltrated with Silicates, 121.
Steinhag, Eozoon of, 146.
Stromatopora, 37, 156.
Stromatoporidæ, 165.
Supplemental Skeleton, 64.
Table of Formations, 6.
Trinity Cape, 10.
Tubuli Explained, 66, 106.
Varieties of Eozoon, 135, 236.
Vennor, Mr., referred to, 46, 57.
Wentworth Specimens, 91.
Weston, Mr., referred to, 20, 40, 162.
Wilson, Dr., referred to, 36.
Worm-burrows in the Laurentian, 133, 139.
Butler & Tanner. The Selwood Printing Works. Frome, and London.
* * * * *
Transcriber Notes
The label Plate II was added to the illustration's page. The "NOTES"
sections were standardized to say "NOTES TO CHAPTER ..." and the
sections labeled as (A.), (B.), etc.
End of Project Gutenberg's Life's Dawn on Earth, by John William, Sir Dawson