form, with its bark and wood, and sap and pith, and cones and
innumerable spikelets, seems wonderfully noble and vastly superior in
the scale of creation to a spoonful of salt; yet every one of the tiny
grains has, so far as we know, full as much sense and as much power
of enjoyment as the stately tree. The mineral and the vegetable are,
in fact, alike destitute of any qualities on which a comparison of
dignity can properly be founded. The organic depends ultimately upon
the inorganic for its nutriment. It is itself ultimately reduced to
the inorganic. It does not, therefore, seem incredible that living
organisms, simpler perhaps than any yet detected by the microscope,
should be or should have been produced without generation proper by the
mere combining of inorganic materials.
This is the hypothesis of Spontaneous Generation, so called, or
_abiogenesis_, unproved and extremely difficult of proof, but precisely
filling that gap in the order and continuity of nature which is so
puzzling without it.
Practically it makes no difference to the theory of development
whether the simple organisms from which that theory supposes the more
complicated to be derived, originated at a single era or at several.
The theory does not deny the perpetuation throughout vast ages of
extremely simple organisms. To the general cohesion of the theory,
therefore, it is unimportant whether we affiliate each of these
living motes to a parent like itself, or to a combination of chemical
substances previously without life.
Considering the vast results attributed to the principle of
_variability_, it has been thought strange that any organisms
should through great cycles of time have escaped its operation, and
transmitted their original simplicity to an endless succession of
descendants.
On the hypothesis of spontaneous generation working continuously this
difficulty would disappear; simple organisms would be continually
losing their simplicity by variation, but new organisms of equal
simplicity would continually appear in the world, spontaneously
generated.
It might still be true that all but the least conspicuous members of
the world’s population belong to a single family, or to an extremely
small number of separate lines of descent. If we suppose that, as soon
as the globe was fitted for living occupants, a single simple organism
was spontaneously generated, or, if you please, created, or, in any
other way that may be named, introduced upon the earth, the results in
accordance with actual facts may be logically deduced agreeably to the
various principles of the theory of development. Its descendants would
multiply and replenish the earth, unchecked, in all parts suited to
their conditions of existence, till all such parts were occupied. No
further advance in the population of the world could then take place
until some variation had occurred, making possible the occupation of
new regions, or of the old regions, under new conditions. But the new
species, constituted by some advantageous variation, would be likely
to overrun the whole field, to the almost complete suppression of the
earlier and more simple form. The distance thus gained in the race of
progressive organization it would be likely not only to maintain, but
greatly to increase. Its descendants would vary in more than one useful
direction, till it might, as we have said, become the parent of all
the conspicuous members of the earth’s population. The earliest and
simplest form might still have representatives inheriting its likeness
by direct descent, but unable to make their way in the world, not from
wanting the power to vary, but from finding the world pre-occupied by
species too powerful for them to compete with. In this way they would
be restrained to their original insignificance.
Now exactly the same result would follow, if, instead of being born in
what we consider the ordinary course of parentage, these simple forms
were ever being spontaneously generated. They would find the world
pre-occupied against their advancement in the scale of organization;
they would rarely, if ever, be allowed to lead up by successive useful
variations to highly organized forms; and if ever, only in periods of
time so enormous as to perplex the acutest human understanding.
What is commonly supposed to be the Biblical theory of Creation, is
in truth a theory of spontaneous generation, only multiplying a
million-fold the difficulty, if it be a difficulty, involved in that
hypothesis. Unless we suppose the globe to have always existed, and
always to have been tenanted by creatures endowed with life, we are
forced to believe in the occurrence at some time or other of what,
in the language of science, must have been spontaneous generation.
As there is no historical reason for confining such an occurrence to
any particular era; as science can give no reason why, if it happened
once, it should not happen an indefinite number of times; as all
analogy is in favour of uniform laws of nature rather than exceptional
surprises; and, lastly, as numerous phenomena that have to do with
the reproduction and maintenance of life are all continuous, and
not interjectional--it seems at least an open question whether the
origin of life itself may not also be sometimes, or even continually
repeated. For, imagine what conditions we will to have prevailed when
the elementary substances coalesced, out of which were compounded the
first living being, it is difficult to imagine that the same conditions
should never have recurred to produce a similar result, since the
conditions are so far limited, that they must have been consistent, not
only with the birth, but with the life after its birth, of that most
antique animalcule. So many wonderful and hitherto unsuspected effects
in the working of Nature have of late years been unveiled, so much of
marvellous analysis successfully carried out, that it would surely be
superstitious to despair of finding fresh links in the chain that binds
together the lifeless and the living. Experiments in this direction
may hitherto have failed from want of skill or care, or proper means
at the command of those who conducted them. Yet it is not too much to
ask of men renowned in science, that in pointing out the errors, they
should abstain from discouraging the efforts.
Let it not be thought irreligious to anticipate the possible
establishment of the supposition now under discussion. It cannot be
irreverent to think that the bestowal of life upon a particle of matter
too minute for human eye to see, requires no more special apparatus
than that allotted to the exquisite crystals of the frost. ‘Out of
whose womb came the ice? and the hoary frost of heaven, who hath
gendered it?’ Yet in the workmanship of these a Divine hand is to the
full as visible as in a diatom or a puff-ball. That the life-giving
energy should have been exhausted in a single effort, is contrary
beyond doubt to the analogy of religion, whatever may be thought of the
analogy of nature.
On the other hand, let it not be thought unscientific to advocate the
claims of an unproved hypothesis. It is the nature of hypotheses to
be unproved. As they gather proof, the hypothetical becomes a theory.
At length the theory goes on to demonstration. The use of hypotheses
has often been explained. The human mind is easily exhausted by the
observation of numerous incoherent facts. It is impelled to arrange
and classify, to find some thread or threads of association on which
the facts may be strung, some principle on which they may be parcelled
out into groups. The arrangement may be erroneous, the explanatory
principle untrue; they may be so plausible, so apparently satisfactory,
so fascinating withal in general aspect, as for a long time to hinder
the real solution of great problems; and nevertheless it may be judged
that their services in the advancement of knowledge far outweigh the
hindrances caused by the too servile acceptance accorded them. The
foibles of a great writer may long infect the literature which his
greatness has ennobled. A constitution grandly conceived in proportion
to the moral and social ideas prevailing at the time of its conception
may be clung to with servility long after it has been outstripped
by the progress of civilization. But neither the genius of the poet
nor the skill of the lawgiver could be spared in its own day and
generation; neither could have been sacrificed to prevent the follies
of the plagiarist, or the dulness of eyes that in after ages might read
the letter without discerning the spirit.
We may almost say that a bad hypothesis is better than none; but a
wrong hypothesis need not be a bad one. It may tend so to group around
it the facts contributed by supporters and opponents, that when the
real explanation of them all comes to be suggested, the fraternization
of the confronting armies may be easy, and the truth be greeted and
acknowledged with general acclaim.
THE IMPERFECTION OF THE GEOLOGICAL RECORD.
The general who is for ever counter-marching and skilfully executing
retrograde movements cannot always sustain the enthusiasm of his
own troops, much less excite in his favour that of the civilian
multitude. To many minds, the reliance placed on the imperfection of
the geological record appears to be a rather damaging retreat in the
strategy of science. They were just beginning to believe in geology as
a wonderful revelation of the past history of the globe, when suddenly
they are told that the fragments of that history which have been saved
are merely tattered pages out of different chapters, giving no adequate
notion of the enormous bulk and varied contents of the whole volume.
Since, without the geological evidence of time’s duration and of the
countless changes in organic structures which that duration embraces,
the theory of development could never have been imagined, it seems
half ungrateful and inconsistent in the author of the theory to turn
round upon geological evidence and tax it with its extreme poverty
and even delusive misleading appearances. But, in fact, Mr. Darwin in
no way detracts from the value of geological evidence. The researches
necessary to extend it are invested, to those who accept his theory,
with tenfold interest. The deficiencies and interruptions in it which
he has pointed out as necessarily occurring must sooner or later have
become apparent. They were dangerous to science only as long as they
were unobserved, or not sufficiently taken into account.
That the record is really imperfect is not a matter which admits of
controversy. No one supposes that every species and variety that
ever existed in past ages on the globe is represented at this very
day by fossil specimens in prime enough condition to exhibit all the
characteristics of the creature as it once lived. No one supposes
that, if such specimens existed, all of them ever could or would be
found by human beings. It is not in the nature of a fossil to present
all the characteristics of the creature as it once lived. It cannot
possibly do it; for the fossil is without life and motion. There is no
respiration, no circulation of the blood going on. As a rule, only the
hard parts of the creature, such as shell, scales, or bony skeleton,
can be preserved. In most cases all these relics have been chemically
altered. Nevertheless, in fossils from the very lowest strata, from
the very earliest formations that yield any, we find certain analogies
to creatures now living. We reason from these analogies without any
hesitation to the characteristics which the fossil creature will
probably have presented in its living state. Our reasonings may
often be erroneous, but the mere fact of our accepting the apparent
analogies as a ground for reasoning at all, implies a belief in the
uniformity of the conditions of animal existence between our own times
and the most distant ages of the past. We argue as if generation had
succeeded generation without interruption, not as if there had been
new independent creations from time to time, since these would imply
new conditions replacing the old, and make the argument from analogy
between the items of the different creations of no value. For these
independent creations, whether capricious or not in themselves, could
only exhibit to our minds the symptoms of caprice. The mere fact of
their being independent one of another would be so wanting in congruity
with all the rest of our experience, that we should reasonably expect
their minor details as well as the general plan to be wholly fantastic.
In other words, the fossil memorials of life in past ages, imperfect
as we confess and maintain them to be, still present so many general
resemblances to one another and to living structures of the present
day, that if they do not prove the continuity of life upon the globe,
they cannot be held to prove anything at all; they should be regarded
as a very elaborate practical joke played upon the human reason.
Palæontology is defined as ‘the science which treats of fossil remains
both animal and vegetable.’ This principle of the continuity of life
from age to age may be considered as one of its definite acquisitions.
There is no single point of geological time at which it can be said,
‘at this epoch clearly all old species had passed away, all kinds
of life had become new.’ Not only is there no indication of such a
break, but there is the strongest evidence against any such having
ever occurred. In spite, however, of the completeness of the evidence
required for proving this single conclusion, the general incompleteness
and enormous deficiencies in some parts of the palæontological record
can be established beyond dispute. We are in the position of a man
who has kept the title-deeds to a large estate, while almost all the
estate itself has been buried under the encroachments of the sea. Here
and there some old landmarks may be discernible far out in the waters,
showing the extent of what had once been meadow and woodland, farm and
garden, but unable to show how these were distributed, or to exhibit
any of their details.
Mr. Parfitt, in his paper on ‘Fossil Sponge Spicules,’ told the
Devonshire Association last year (1870) that we have evidence more or
less exact of sponges in a fossil state as far back in time as the
Silurian system, mentioning specimens of _Acanthospongia Siluriensis_,
_Cliona antiqua_, and _Cliona prisca_, and stating in regard to the two
latter that the genus is still in our own seas. He then referred to
large masses of a fossil in the Devonian rocks of Cornwall, believed
by some to be sponges, and by others to be the remains of fish. That
these are in reality fish-remains has, in fact, been shown pretty
conclusively[59]. From this point, however, up to the Great Oolite,
Mr. Parfitt tells us that scarcely a vestige of the sponges is to be
found, although since that time they have been very abundant. Between
the Silurian and the Great Oolite the interval of time must have
been enormous. It is occupied by a vast series of sedimentary rocks,
embracing very varied mineral characteristics. From this series our
museums have been, and are still being, supplied with vast heaps of
fossil organic structures, including among numerous others, plants and
corals and fish and reptiles. Through all that protracted period there
is no reason to suppose, in regard to the outer rind of the globe, that
the general conditions of earth, air, and water were other than they
are now. All England may have been under water; delicate creatures may
have wintered at the North Pole for the sake of its genial climate;
and an infinity of other local and temporary differences may have
prevailed, without making the habitable globe of those days essentially
different from our own. The laws of chemistry and mechanics, the laws
of heat and motion, must have been just the same as they are now.
Then, as now, there must have been oceans and continents, winds and
currents, forests growing, decaying, and being buried, sand and chalk
being deposited in layers, molten minerals thrown up by volcanoes,
ice forming at a definite temperature, glaciers scoring the rocks,
icebergs transporting boulders, rains and rivers slowly washing down
the hills, and waves corroding the cliffs on the sea-shore. We have
evidence also that life in many forms abounded. Those forms, though
seldom transmitted to creatures of the present day with anything
approaching an exact likeness, can yet be classified under the same
general names with the most modern forms of life. Now sponges are forms
of an extremely simple organization. The silicious spicules are well
adapted for the wear and tear of a fossil existence. In the greensand
and the chalk they are actually found in extraordinary abundance. It
would be inconvenient upon any theory to have to suppose these very
simple structures introduced into the world for the first time quite
late in the series of living organisms, and after beings much more
complicated and higher in the scale of existence, unless, indeed, we
suppose that about the time of the Great Oolite the evolution of man
was first thought of, and the sponge accordingly prepared for him to
wash his face with. But even if the bath and the basin be admitted
as the final causes of sponge-existence, the conception of it must
be carried back, as we have seen, to the Silurian period; while,
according to Mr. Parfitt, the immense interval of Lias and Trias,
Permian, Carboniferous, and Devonian remains black and spongeless,
as though it were the appropriate era of the great unwashed. But if
the Darwinian theory be a true one, sponge-life having begun in the
Silurian period, and being in existence now, must have been continuous
through the whole interval; every single deposit in the entire series
since the Silurian must have been contemporary with some of the
sponges; and, as a matter of fact, Mr. Parfitt’s statement, however
true of the condition of our knowledge a few years back, must now be
qualified by the addition of several species spread over the interval
in Britain alone, even if we exclude some indefinite structures, of
which no opinion can be at present pronounced with safety. Mr. Parfitt
himself, in a paper read at Honiton in 1868, remarks that ‘the Devonian
formation has furnished a great number of specimens of what appear to
be species of sponges.’ From Permian and Triassic beds on the continent
of Europe, a very large number of forms are said to be more or less
distinctly made out. Mr. Salter, in 1864, reported the discovery of
Protospongia Fenestrata in the Lingula flags of St. David’s, thus
carrying back this form of life beyond the Silurian to the Cambrian
era. It is an interesting illustration of the great ambiguity of these
ancient fossils, that two such authorities as Mr. Salter and Dr.
Bowerbank differed about the Protospongia, the one supposing it to
exhibit the spicules, the other the fibre of the sponge. The simple
facts that species have to be moved backwards and forwards between the
amorphozoic and zoophytic groups, that relics may pass for fish in one
year and sponges in another, and by-and-by be recognised again as fish,
show the often imperfect condition of the record, even where it is not
a complete blank.
Where direct evidence of any kind is still unavailable, it may
possibly be said that no sponges are found for such and such a period,
because none existed in it. The plausibility of such an opinion can
only be tested in fresh illustrations of the general argument. The
coalfield of Nova Scotia has been described by Professor Dawson
of Montreal. As it afforded a fine field for the exertions of the
geologist, so it repaid him by its great richness in the fossil remains
of plants. But in the coal formations of England and of Westphalia
insects also had been found of different genera in addition to plants,
while Nova Scotia, with all its vegetable wealth, yielded the anxious
explorer but a single specimen of the still more interesting relics.
That specimen consisted of the head and some other fragments of a large
insect, probably neuropterous. That single specimen Professor Dawson
tells us he found in a coprolite, in the fossil excrement of a reptile
enclosed in the trunk of an erect sigillaria. Could any one invent a
more curious cabinet to preserve so fragile a specimen for millions
of years? Can it in this case be argued, that of insect remains
nothing was found in the carboniferous of Nova Scotia but the head
and some other appurtenances of a single neuropterous insect, because
that head and those appurtenances were all that had ever flourished
there? It cannot so be argued, not only because the analogies of the
carboniferous formation in other parts of the world are conclusive
against such argument, but also because within the last three or four
years, after long and diligent search, two more species have been added
to the collection of carboniferous insects from Nova Scotia itself.
Two delicate wings, one very large and one small, have been found, each
sealed, as it were, with a fern-leaf; each a frail but enduring record
of life that must once have been brilliant and abundant[60].
When the zeal of a collector adds a new species to those already
known, by finding the fragment of a butterfly’s wing that had been for
millions of years in a seam of coal, how many considerations are forced
upon the mind! Our sensitive nerves are comparatively seldom troubled
by the perceived presence of dead creatures. With the exception of our
own food, such sights are pretty well confined to the carcase of a dog
floating on a pool, the feathers of a torn bird, a parched mole, and a
sprinkling of blue-bottles in an unused room. Yet countless millions
of creatures are annually dying, ready and willing to become fossils.
Fossils, however, they do not become, simply because other creatures
eat them up. For this reason alone, not one in ten thousand of any
particular terrestrial species is likely to become fossil, because
to some creature or another it is almost sure to be good eating, and
therefore in the living state or the dead, sure to be ravenously seized
upon and devoured.
Some forms of marine life are indeed represented by a wonderful number
of specimens or fragments of specimens. Silicious and calcareous exuviæ
of minute creatures deposited in the still depths of the ocean may be
preserved by myriads, but neither these ‘in number numberless’ nor the
giant-bones of ancient Saurians convey any adequate notion of the whole
population of the globe at any one era. The palæontologist, guiding
himself only by prominent details of this description, would be like
a child over a child’s history of England, to whom the fabric of the
Constitution and the Reformation of the Church seem matters obscure,
and scarcely worthy of notice, while Alfred burning the cakes, and
Henry VIII in his well-known character of Bluebeard, stand out in bold
relief.