observation, and partly to the views which would naturally be held by
poets and thinkers, we may attribute the belief which has been held
by man, simple and philosophic alike, since first men began to think,
until, we may say, the third quarter of the nineteenth century--the
belief that the lowest of living things arose by a natural genesis or
so-called spontaneous generation in suitable materials already provided
on the land or in the sea. It was not suggested or believed that very
large and conspicuous living creatures were thus bred, though it is
true that the ancients thought even crocodiles to be generated by the
action of the sun upon the slime of the Nile. The living creatures
supposed to arise naturally in the womb of earth--the all-mother--were
mostly small creatures, like insects and worms. The ordinary belief of
the uninstructed to-day--a belief which they share with the greatest
thinkers of antiquity and the Renaissance--is that the cheese-mite, for
instance, is evolved from the substance of the cheese. Now, it is of
particular moment to observe the vast contrast between the significance
of this belief prior to the publication of “The Origin of Species” and
its significance to-day. Before we accepted the doctrine of organic
evolution, the supposed spontaneous origin of the cheese-mite in
cheese, or of the maggot in putrid meat, was of no very great moment;
a maggot or a cheese-mite is an extremely insignificant object. So far
as the great problems of the universe are concerned, a cheese-mite, as
we say, is neither “here nor there,” and its spontaneous generation was
not regarded as a fact of any great moment.
But then there arose Darwin, who, in establishing the doctrine of
organic evolution already supported by his own grandfather, by Lamarck,
and Goethe, and Herbert Spencer, gave an entirely new importance to
the question. He demonstrated how we could conceive the evolution of
all organisms, including man, from a “few simple forms,” under the
continuous influence of natural law; and thus such forms ceased to
be insignificant, and the manner of their genesis came to be a vital
problem in more senses than one. Such organisms--the mite, the maggot,
and even the mould--could no longer be regarded as insignificant, for
they were revealed as not unlike the ancestors of man himself.
[Sidenote: Evolution a Continuous Process]
The question of the beginning of life upon the earth had only to be
satisfactorily answered for the establishment of the belief in a
continuous process of evolution by natural law, even from the very
beginning of the earth itself “without form and void,” until the
production of the highest living organisms which it displays in our
own time. And all ages, even by the mouths of their great thinkers and
closest observers, had agreed in giving an apparently satisfactory
answer to this question. It might well have been thought that Darwin
was quite entitled to ignore altogether, as he did, the question of
the origin of life. Everyone knew, so to say, that simple living
organisms were every day evolved in organic refuse and elsewhere.
Darwin himself, if we may judge from a casual remark in a letter,
regarded the question apparently as purely speculative, and of small
real moment. It is all rubbish, he says, thinking about the origin of
life; we might as well argue about the origin of matter. We must beware
of illegitimately attributing opinions to the immortal dead, but this
remark, though a casual one, does seem to suggest that Darwin regarded
these two questions as on all-fours, if not, indeed, as different forms
of the same question, and that, if he had actually formulated his
views, they would have taken the shape of the doctrine which asserts
that life is implicit and potential in matter; in other words, that
when suitable conditions arose--such, for instance, as the presence of
liquid water--matter would display the properties of life.
[Sidenote: An Abyss that could not be Bridged]
Now, the remarkable fact--one of the most striking in the history of
science--is that the time-honoured belief in spontaneous generation
should have been attacked, and attacked with apparent success, just
at the very time when it would otherwise have begun to assume real
philosophic importance. For ages it had been accepted, taken as a
matter of course, and not regarded as having any particular bearing
upon the supreme questions. Then there came the time when this belief
would have been an all-important link, without which the chain of
evolution could not be completed, a link without which we were left
to contemplate a perfect chain of inorganic evolution--the history of
the earth before life--and a perfect chain of organic evolution--the
history of life upon the earth, with an abyss between the two that
could not be bridged, for how came life where there was no life? A
series of experiments were made, experiments in which, strikingly
enough, some of the greatest evolutionists of the day took a leading
part, and these seemed to upset, just when it was most wanted by
themselves for the establishment of their new doctrine, the belief
which had gone without question for so many ages.
[Sidenote: Is Life only Self-movement?]
Now, some may be inclined to wonder how it should be that certain
pioneers of the new doctrine of evolution, such as Tyndall and Huxley,
should devote themselves with such persistence and labour and force
to the overthrow of a doctrine which was so necessary for the complete
establishment of their own case--so much so, that when they had
overthrown it, they found themselves, as regards their own doctrine
of evolution, placed in a difficulty from which they did not live to
emerge. It is my own belief that this question can be answered, and
the answer is of strict relevance to our present inquiry. I believe
that Huxley and Tyndall were largely impelled by the desire to oppose
a doctrine of the nature of life which was current in their time and
is usually called “vitalism.” We shall not begin to understand the
question of the beginning of life upon the earth, as that question may
be legitimately stated to-day, unless we fully realise in what terms
the doctrine of spontaneous generation was accepted in the past, and
an understanding of this will teach us that the present-day revival of
this doctrine presents it in a form very different from that which it
so long held. Our discussion must be somewhat philosophic in character,
but the question at issue is a highly philosophic one, and the reason
why we have made so little progress in answering it hitherto is that
men of science have too frequently discussed it without paying any
serious attention to the profound philosophic questions which really
underlie it. We have permitted ourselves to talk freely about life and
matter, whilst claiming the right to take for granted the absolute
validity of our conceptions of life and our conceptions of matter.
It was universally held by those, philosophic and simple, who also held
throughout so many centuries the belief in spontaneous generation, that
there is an overwhelming contrast between living and lifeless matter,
and it was their belief in this overwhelming contrast that led them
to give to the doctrine of spontaneous generation, as they held it, a
form which cannot possibly be defended. The great character of life was
conceived to be self-movement, this self-movement being displayed in
the matter which composed the living organisms. But it was universally
held that matter, as it was seen otherwise than in living organisms,
was obviously and notoriously inert, gross, brute, and dead.
[Sidenote: The Influence of Plato]
The great influence of Plato taught men to despise matter in this
fashion, and there was the everyday experience that a stone lies where
it is placed until something from outside moves it, being, therefore,
inert, whilst a living creature such as a bird moves freely at its own
will. The more strongly men held the natural matter of which the earth
is composed to be inert, the more necessary was it to suppose that
when life was displayed in it the difference consisted in the taking
possession of this dull clay by a vital force--a mystic and wonderful
principle of quickening--which endowed even gross, inert matter with
activity and power. From the time of Plato until the last few years of
the nineteenth century thinkers vied with one another in insisting upon
the impotence and grossness and inertness of matter, and each fresh
insistence upon this doctrine rendered more necessary a corresponding
doctrine of vital force or vitalism, which should explain the amazing
transformation undergone by, let us say, the gross and inert matter
composing food, when that food was converted by the “living principle”
into the tissue of a living creature, and then displayed self-movement.
[Sidenote: Philosophy of Dead Matter]
[Sidenote: The Great Work of Pasteur]
This doctrine of vitalism, which held sway for so long, was naturally
invoked to explain the origin of life upon the earth, when the advance
of astronomy and geology demonstrated a natural evolution for the
earth and proved that there must have been a time when no life was
possible upon it. The prevalent conception of matter came in at this
point and denied altogether any such monstrous doctrine as that the
wonderful thing called life could spontaneously arise in the despicable
thing called matter. The material of the earth, whether solid, liquid
or gaseous, consisted of eternal, unchangeable, and indestructible
atoms. These were moved as forces from outside moved them. They had
no energy or power of their own. Men simply thought of them as of
incredibly minute grains of sand of various shapes and sizes, and it
was as impossible to conceive of life being spontaneously generated
in a chance heap of inert atoms as to conceive that a heap of grains
of sand should organise themselves into a little organism. As for
spontaneous generation occurring on the earth to-day, the development
of mites from cheese and so forth, that was a very different matter,
men must have thought--in so far as they thought at all--since cheese
and flesh and so forth were themselves products of life. It is well
worth noting that the common doctrine of spontaneous generation was
always held in reference to organic materials, such as the slime of the
Nile--not the dry sand of the desert. The reader may be inclined to say
that men’s beliefs on this subject in the past generation make very
confused reading, and indeed, that is true. But the fact is that their
beliefs were most confused. The work of Darwin had staggered everybody,
and straightforward, systematic, unprejudiced thinking was very nearly
impossible in the welter of controversy. Nevertheless, something
apparently definite was done. The doctrine of the beginning of life
upon the earth was left almost undiscussed, and the accepted notion
of the nature of matter--a notion which to us who know radium seems
puerile--was left unchallenged in all its falsity. But the work of the
great French chemist Pasteur led to a close examination of the belief
that humble forms of life are daily produced from lifeless organic
materials, and the conclusion was reached that no such spontaneous
generation occurs.
[Sidenote: Every Living Thing from a Living Thing]
This conclusion is of great importance in the history of modern
thought, and it was proclaimed with much rejoicing and vigour as a
great achievement of science, whilst some of its chief advocates
seemed at times to forget the extreme awkwardness of the inferences
which had to be made from it. The doctrine may be stated in Latin in
the form of the familiar dogma, “Omne vivum ex vivo,” every living
thing from a living thing. Just as the existence of a man is quite
sufficient to prove to us the prior existence of living human parents,
just as we feel sure that every beast of the field has had living
parents and that every oak has sprung from an acorn developed in a
previous oak, so, according to the doctrine of “Omne vivum ex vivo,”
we must believe that every living creature, whether human, animal, or
vegetable, whether as big as the mammoth or as small as the smallest
microbe not one-twenty-thousandth part of an inch in diameter, has
sprung from living parents. Nature, according to this doctrine, was
divided--as Nature, being a mighty whole, can never be divided--into
two absolute categories, the living and the lifeless, or living matter
and dead matter. Dead matter was notoriously dead and impotent, and
life could not conceivably arise in it, though it could be used by life
for purposes of food. On the other hand, living matter rejoiced in the
possession of all those great attributes which lifeless matter lacked,
and, in accordance with the contrast between the two kinds of matter,
the living could never be produced from the lifeless but only from the
living: for every creature, microbe or mammoth or man, we must trace
back in imagination a series of living ancestors, differing perhaps in
various characters, but always living. This series must be traced back
and back and back until----?
[Sidenote: Life Evolved from the Lifeless]
And there the difficulty arose. For the uninhabitableness of the
primitive earth was a fact of which men of science were as certain
as if from some habitable planet they had been able to gaze upon it.
Notwithstanding the dogma of “Omne vivum ex vivo,” it was impossible to
assert that every living creature has an _endless_ series of ancestors.
How, then, did life begin?
What we may call the doctrine of the older orthodoxy--the doctrine of
special creation, of supernatural interposition for the introduction
of a new entity into the scheme of things--offered one alternative. To
accept it, however, would be to abandon the whole modern conception
of natural law and of a universe which was not created once on a day,
and has not been tinkered with subsequently, but from everlasting to
everlasting is the continuous expression to us of the Infinite and
Eternal Power which to some eyes it veils and to others it reveals.
Unless we are to abandon our philosophy, this alternative cannot be
accepted, and it is now accepted by no philosophic thinker.
[Illustration: BUFFON PLATO LAMARCK
BERTHELOT HERSCHEL CLERK MAXWELL
D^{R.} BASTIAN DARWIN TYNDALL
HUXLEY LORD KELVIN SPENCER
MASTER THINKERS WHO HAVE CONTRIBUTED TO OUR KNOWLEDGE OF LIFE
Photos by Gerschel, Maull & Fox, E. Walker, London Stereoscopic,
Barraud, and Mills
]
Thus, whether “Omne vivum ex vivo” be true or false to-day, we are
compelled to accept the only other alternative, which is that it has
not always been true, or, in other words, that life was spontaneously
evolved from the lifeless (so-called) at some remote age in the past.
Just at the present time philosophic biology is out of fashion. Minds
of the great cast which endeavour to see things in their eternal
aspect have been lacking to the science of life since the days when
Huxley and Spencer were in the plenitude of their powers. Anyone who
cares to compare the principal reviews of the last decade with those
same reviews from the year of, say, 1875 to 1890, can readily see
this fact for himself. In the absence of that deliberate thought and
discussion without which clear ideas on any subject are impossible,
what may be called the official opinion of biology at the present time
is thus most remarkable and contradictory. On the one hand, it is
strenuously asserted as a matter of dogma that at the present day no
life is produced or producible upon the earth except by the process of
reproduction of previously existing life; and on the other hand it is
asserted--when the direct question is put, though otherwise the subject
is simply ignored--that life must somehow or other have been naturally
evolved in the past, presumably once and for all. I have called this
opinion contradictory, and it is indeed far more contradictory and
unsatisfactory than it may at present appear. The obvious question that
the critic asks is, “If then, why not now?”
[Sidenote: “If then, why not now?”]
[Sidenote: Is Life Now Arising from the Lifeless?]
The answer alleged is that, of course, the experiments of Pasteur and
Tyndall, to which some reference must afterwards be made here, merely
demonstrated the impossibility of the spontaneous generation of life
in our own day or under any conditions similar to those of our own
day; but doubtless the first few simple forms of living matter arose
by natural processes at some distant epoch “when the conditions were
very different from those that obtain to-day.” Now it happens to be
true that every difference between past and present conditions which
physics and geology and chemistry can assert tends to the probability
that if spontaneous generation is impossible now, it must have been a
hundredfold more impossible a hundred million years ago. Yet for some
three decades the great majority of biologists have been content to
believe that spontaneous generation is impossible now, even though
land and sea and sky are packed with organic matter under the very
conditions which obviously favour life--as the all but omnipresence
of life abundant to-day demonstrates--but that spontaneous generation
was possible in the past when, by the hypothesis, there was no
organic matter present at all, and when life had to arise in the union
and architecture of such simple substances as inorganic carbonates!
Such biologists are like those who know that the human organism can
be developed from the microscopic germ in a few years, but find it
incredible that man can have been developed from lowly organisms in
æons of æons. Nor has any living biologist even attempted to make an
adequate answer to the question, why what is impossible now should
have been possible a hundred million years ago. On the contrary, so
soon as the matter is looked at philosophically, we see that all the
probabilities, all the analogies, all the great generalisations of
science, are in favour of the belief that life must be arising from the
lifeless now, as in the past, whenever certain conditions, such as the
assemblage of carbon, oxygen, nitrogen and hydrogen in the presence of
liquid water, are satisfied.
For the moment, however, I propose to postpone this question of the
truth of “Omne vivum ex vivo” at the present day, for I desire to
throw into the forefront of my argument two quite recent developments
of science, unreckoned with because non-existent in the controversy
of the ’seventies, and in my judgment not yet duly appraised to-day.
In the present and future discussion of the manner and causation of
that supreme event in the earth’s history, the beginning of life upon
it, we must reckon with two new orders of inquiry relating to facts
unthinkably contrasted in physical magnitude yet equally relevant to
our subject. The first series of facts with which I will deal are
_astronomic_, and the second _atomic_.
[Sidenote: The Evidence from Other Worlds]
[Sidenote: Vegetable Life on Mars]
In discussing the origin of life upon the earth, we of the twentieth
century must recognise such facts as may be obtainable in regard to
life upon other orbs than ours. Now, in the first place, there is at
least one illustrious contemporary astronomer, Professor Pickering,
the chief living student of the moon, in whose opinion there are many
evidences upon our satellite of the action of vegetation, either past
or present. This, of course, is not the place for a discussion of
that evidence; it is, however, the place to record the most highly
qualified opinion at present obtainable, and to remind ourselves of
the certainty that when the moon was first borne--or born--from the
earth, life cannot possibly have been evolved, since the conditions
of temperature alone, to name one factor, were such as life could not
sustain, no liquid water being extant. There is some reason to suppose,
then, that, whatever the present case may be, life was at one time
spontaneously evolved upon the moon.
The second piece of astronomical evidence relevant to our inquiry is
afforded by the planet Mars. This, of course, is a much controverted
question, which cannot receive any discussion here. It suffices to
note that Professor Lowell, who is admittedly the greatest living
authority on Mars, has observed and photographed, not merely to
his own satisfaction, but to that of an ever increasing number of
astronomers, signs of vegetation upon Mars. I will say nothing here
as to the existence of intelligent beings there. That fascinating and
momentous question, upon which there will doubtless be difference
of opinion for some time to come, does not now concern us. It is of
quite sufficient significance for our present purpose if the existence
of merely vegetable life, and no more, upon the planet Mars can be
demonstrated, and there are now very few astronomers indeed who
question this demonstration, however chary they may be of going any
further. I submit that the question of the beginning of life upon
the earth should not be considered without reference to the evidence
which suggests the spontaneous origin of life upon the moon, and to
the practically positive demonstration of the present existence, with
seasonal alternations, as on our own earth, of vegetable life in the
watered areas of Mars.
[Sidenote: The Earth’s Crumbling “Foundations”]
These considerations were entirely unknown to the great
controversialists of a generation ago; but there is another order of
facts, entirely unimagined by them, which are now demonstrable and
admitted. For them, or for most of them, the ancient conception of
matter which we trace to Plato was substantially true; nay, more.
The recent work of the physicists and chemists had endowed that
ancient conception of matter as gross and inert and dead with a new
concreteness and vividness. One of the greatest physicists of the age,
James Clerk-Maxwell, in his famous address to the British Association,
spoke of atoms as the “foundation stones of the visible universe, which
have existed since the creation unbroken and unworn.” The accepted
conception of an atom was that of a passive thing; it had its own
inherent shape and properties, which were impressed upon it at its
creation. It had “the stamp of the manufactured article,” as Sir John
Herschell said, and throughout its endless history it responded to and
behaved under the influence of external forces in due accordance with
its shape and size. But it was unchangeable, inert and brute, the sport
of its surroundings, like the mote in the sun-beam.
[Sidenote: Immeasurable Ocean of Energy]
But to-day we stand amazed at such conceptions. We have learnt that
within the atoms of matter there is a fund of energy so incalculably
vast that the sum total of all the energies previously recognised, and
now to be styled extra-atomic, is as nothing compared with it. This
is a change indeed, that all the energies hitherto known to us should
be merely the overflow trickling from the immeasurable ocean of the
intra-atomic energy, the very existence of which has been formally and
repeatedly denied by practically all thinkers from Plato down to our
own time. Matter is not gross and inert, brute and dead. The atom, the
so-called unchangeable foundation stone, is, on the contrary, itself
an organism, the theatre of Titanic forces about which we at present
know practically nothing except that they certainly exist, and are
powerful beyond all our previous conceptions. The atom is no atom, but
a microcosm; it is no more the unit of inorganic matter than the cell
is really the unit of living matter.
Now it is surely evident on consideration, though the significance
of the change has been ignored, that the whole discussion of the
spontaneous origin or evolution of life in matter takes an entirely
new shape when our old and widely erroneous conception of matter is
abandoned, and a true one is substituted. Life is a marvellous and
characteristic demonstration of energy. When the origin of this energy
in matter was formerly discussed, we were told that the constituent
parts of matter contain no energy at all, but now we know that a quite
overwhelming proportion of the sum total of universal energy is to be
found there, and nowhere else. This is one of the most revolutionary
advances in the whole history of thought, and its full significance has
yet to be recognised.