FURTHER SPECULATION AS TO THE ORIGIN AND NATURE OF LIFE[6]
_Preliminary Remarks on Recent Views in Chemistry._
It is a fact extremely familiar to chemists that the groupings possible
to atoms of carbon are exceptionally numerous and complicated, each
carbon atom having the power of linking itself with others to an
extraordinary extent, so that it is no exceptional thing to find a
substance which contains twenty or thirty atoms of carbon as well as
other elements linked together in its molecule in a perfectly definite
way, the molecule being still classifiable as that of a definite
chemical compound. But there are also some non-elementary bodies which,
although they are chemically complete and satisfied, retain a
considerable vestige of power to link their molecules together so as to
make a complex and massive compound molecule; and these are able not
only to link similar molecules into a more or less indefinite chain,
but to unite and include the saturated molecules of many other
substances also into the unwieldy aggregate.
[Footnote 6: An article reprinted from the _North American
Review_ for May 1905.]
Of the non-elementary bodies possessing this property, _water_ appears
to be one of the chief; for there is evidence to show that the ordinary
H-2-O molecule of water, although it may be properly spoken of as a
saturated or satisfied compound, seldom exists in the simple isolated
shape depicted by this formula, but rather that a great number of such
simple molecules attach themselves to each other by what is called
their residual or outstanding affinity, and build themselves up into a
complex aggregate.
The doctrine of residual affinity has been long advocated by Armstrong;
and the present writer has recently shown that it is a necessary
consequence of the electrical theory of chemical affinity,[7] and that
the structure of the resulting groupings, or compound aggregates, may
be partially studied by means of floating magnets, somewhat after the
manner of Alfred Mayer.[8]
[Footnote 7: See _Nature_, vol. 70, p. 176, June 23, 1904.]
[Footnote 8: See an article on "Modern Views of Chemical Affinity"
by the present writer in a magazine called _Technics_, for
September 1904.]
It may be well here to explain to students that one of the lines of
argument which lead to the conclusion that the water molecule, as it
ordinarily exists, is really complex and massive, is based upon
measurements of the Faraday dielectric constant for water; for this
constant, or "specific inductive capacity," is found to be very large,
something like 50 times that of air or free ether; whereas for glass it
is only 5 or 6 times that of free space. The dielectric constant of a
substance generally increases with the density or massiveness of its
molecule,—indeed, the value of this constant is one of the methods
whereby matter displays its interaction with and loading of the free
ether of space,—and any such density as the conventional nine times
that of hydrogen for the molecule of water would be wholly unable to
explain its immense dielectric constant.
The influence of the massiveness of a water molecule is also displayed
in its power of tearing asunder or dissociating any salts or other
simple chemical substance introduced into it; common salt, for
instance, is found always to have a certain percentage of its molecules
knocked or torn asunder directly it is dissolved in water, so that, in
addition to a number of salt molecules in solution, there are a few
positively charged sodium atoms and a few negatively charged chlorine
atoms, existing in a state of loose attraction to the water aggregate,
and amenable to the smallest electric force; which, when applied, urges
the chlorine one way and the sodium the other way, so that they can be
removed at an electrode and their place supplied by freshly dissociated
molecules of salt, thus bringing about its permanent electro-chemical
decomposition, and enabling the water to behave as an electrolytic
conductor directly a little salt or acid is dissolved in it.
The power of the water molecule to associate itself with molecules of
other substances is illustrated by the well-known fact that water is an
almost universal solvent. It is its residual affinity which enables it
to enter into weak chemical combination with a large number of other
substances, and thus to dissolve those substances. The dissolving power
usually increases when the temperature is raised, possibly because the
self-contained or self-sufficient groupings of the water molecules are
then to some extent broken up and the fragments enabled to cling on to
the foreign or introduced matter instead of only to each other. The
foreign substance is apt to be extruded again when the liquid cools,
and when the affinity of the water-aggregates for each other resumes
its sway. Very hot water can dissolve not only the substances
familiarly known to be soluble in water, but it can dissolve things
like glass also; so that glass vessels are unable to retain water kept
under high pressure at a very high temperature, approaching a red heat.
Another material which also seems to have the power of combining with a
number of other bodies, under the influence of the loose mode of
chemical combination spoken of as residual affinity, is carbon; so that
a block of charcoal can absorb hundreds of times its own bulk of
certain gases.
Indeed, Sir James Dewar has recently employed this absorbing power of
very cold carbon to produce a perfect kind of vacuum, which may,
perhaps, be the nearest approach to absolute vacuum that has yet been
attained: probably higher than can be attained by any kind of
mechanical or mercury pump.
_Unexpected Influence of Size._
Suppose now a substance contains a great number of carbon molecules and
a great number of water molecules, each of which has this residual
affinity or power of clinging together well developed, what may be
expected to be the result? Surely, the formation of a molecule
consisting of thousands or hundreds of thousands of atoms, constituting
substances more complex even than those already known to or analysable
by organic chemistry; and if these complex molecules likewise possess
the adhesive faculty, a grouping of millions or even billions of atoms
may ultimately be formed. (A billion, that is a million millions, of
atoms is truly an immense number, but the resulting aggregate is still
excessively minute. A portion of substance consisting of a billion
atoms is only barely visible with the highest power of a microscope;
and a speck or granule, in order to be visible to the naked eye, like a
grain of lycopodium-dust, must be a million times bigger still.) Such a
grouping is likely to have properties differing not only in degree but
in kind from the properties of simple substances.
For it must not be thought that aggregation only produces quantitative
change and leaves quality unaltered. Fresh qualities altogether are
liable to be introduced or to make their appearance at certain
stages—certain critical stages—in the building up of a complex mass
(_cf._ p. 71).
The habitability of a house, for instance, depends on its possessing a
cavity of a certain size; there is a critical size of brick-aggregate
which enables it to serve as a dwelling. Nothing much smaller than this
would do at all. The aggregate retains this property, thus conferred
upon it by size, however big it may be made after that; until it
becomes a palace or a cathedral, when it may perhaps reach an upper
limit of size at which it would be crushed by its own weight, or at
which the span of roof is too great to be supported. But the
difference, as regards habitability, between a palace and a hovel is
far less than that between a hovel and one of the air-holes in a brick
or loaf, or any other cavity too small to act as a human habitation.
The difference as regards habitability is then an infinite difference.
To take a less trivial instance; a planet which is large enough to
retain an atmosphere by its gravitative attraction differs utterly, in
potentiality and importance, from the numerous lumps of matter
scattered throughout space, which, though they may be as large as a
haystack or a mountain or as the British Isles, or even Europe, are yet
too small to hold any trace of air to their surface, and therefore
cannot in any intelligible sense of the word be regarded as habitable.
One of the lumps of matter in space can become a habitable planet only
when it has attained a certain size, which conceivably it might do by
falling together with others into a complex aggregate under the
influence of gravitative attraction. The asteroids have not succeeded
in doing this, but the planets have; and, accordingly, one of them, at
any rate, has become a habitable world.
But observe that the great size and the consequent retention of an
atmosphere did not generate the inhabitants; it satisfied one of the
conditions necessary for their existence. How they arose is another
matter. All that we have seen so far is that an aggregate of bodies may
possess properties and powers which the separate bodies themselves
possess in no kind or sort of way. It is not a question of degree, but
of kind.
So also, further, if the aggregate is large enough, very much larger
than any planet, as large as a million earths aggregated together, it
acquires the property of conspicuous radio-activity, it becomes a
self-heating and self-luminous body, able to keep the ether violently
agitated in all space round it, and thus to supply the radiation
necessary for protecting the habitable worlds from the cold of space to
which they are exposed, for maintaining them at a temperature
appropriate to organic existence, and likewise for supplying and
generating the energy for their myriad activities. It has become in
fact a central sun, and source of heat, solely because of its enormous
size combined with the fact of the mutual gravitative attraction of its
own constituent particles. No body of moderate size could perform this
function, nor act as a perennial furnace to the rest.
_Application to Protoplasm._
Very well then, return now to our complex molecular aggregate, and ask
what new property, beyond the province of ordinary chemistry and
physics, is to be expected of a compound which contains millions or
billions of atoms attached to each other in no rigid, stable, frigid
manner, but by loose unstable links, enabling them constantly to
re-arrange themselves and to be the theatre of perpetual change,
aggregating and reaggregating in various ways and manifesting ceaseless
activities. Such unstable aggregates of matter may, like the water of a
pond or a heap of organic refuse, serve as the vehicle for influences
wholly novel and unexpected.
Too much agitation—that is, too high a temperature—will split them up
and destroy the new-found potentiality of such aggregates; too little
agitation—that is, too low a temperature—will permit them to begin to
cohere and settle down into frozen rigid masses insusceptible of
manifold activities. But take them just at the right temperature, when
sufficiently complex and sufficiently mobile; take care of them, so to
speak, for the structure may easily be killed; and what shall we find?
We could not infer or guess what would be the result, but we can
observe the result as it is.
The result is that the complexes group themselves into minute masses
visible in the microscope, each mass being called by us a "cell"; that
these cells possess the power of uniting with or assimilating other
cells, or fragments of cells, as they drift by and come into contact
with them; and that they absorb into their own substance such portions
as may be suitable, while the insufficiently elaborated portions—the
grains of inorganic or over-simple material—are presently extruded.
They thus begin the act of "feeding."
Another remarkable property also can be observed; for a cell which thus
grows by feeding need not remain as one individual, but may split into
two, or into more than two, which may cohere for a time, but will
ultimately separate and continue existence on their own account. Thus
begins the act of "reproduction."
But a still more remarkable property can be observed in some of the
cells, though not in all; they can not only assimilate a fragment of
matter which comes into contact with them, but they can sense it,
apparently, while not yet in contact, and can protrude portions of
their substance or move their whole bodies towards the fragment, thus
beginning the act of "hunting"; and the incipient locomotory power can
be extended till light and air and moisture and many other things can
be sought and moved towards, until locomotion becomes so free that it
sometimes seems apparently objectless—mere restlessness, change for
the sake of change, like that of human beings.
The power of locomotion is liable, however, to introduce the cell to
new dangers, and to conditions hostile to its continued aggregate
existence. So, in addition to the sense of food and other desirable
things ahead, it seems to acquire, at any rate when still further
aggregated and more developed, a sense of shrinking from and avoidance
of the hostile and the dangerous,—a sense as it were of "pain."
And so it enters on its long career of progress, always liable to
disintegration or "death"; it begins to differentiate portions of
itself for the feeding process, other portions for the reproductive
process, other portions again for sensory processes, but retaining the
protective sense of pain almost everywhere; until the spots sensitive
to ethereal and aerial vibrations—which, arriving as they do from a
distance, carry with them so much valuable information, and when duly
appreciated render possible perception and prediction as to what is
ahead—until these sensitive spots have become developed into the
special organs which we now know as the "eye" and the "ear." Then,
presently, the power of communication is slowly elaborated, speech and
education begin, and the knowledge of the individual is no longer
limited to his own experience, but expands till it embraces the past
history and the condensed acquisition of the race. And thus gradually
arises a developed self-consciousness, a discrimination between the
self and the external world, and a realisation of the power of choice
and freedom,—a stage beyond which we have not travelled as yet, but a
stage at which almost all things seem possible.
The first two properties, assimilation and reproduction, overshadowed
by the possibility of _death_, are properties of life of every kind,
plant life as of all other. The power of locomotion and special senses,
overshadowed by the sense of _pain_, are the sign of a still further
development into what we call "animal life." The further development,
of mind, consciousness, and sense of freedom, overshadowed by the
possibility of wilful error or _sin_, is the conspicuous attribute
of life which is distinctively human.
Thus, our complex molecular aggregate has shown itself capable of
extraordinary and most interesting processes, has proved capable of
constituting the material vehicle of life, the natural basis of living
organisms, and even of mind; very much as a planet of certain size
proved capable of possessing an atmosphere.
But is it to be supposed that the complex aggregate _generated_ the
life and mind, as the planet generated its atmosphere? That is the
so-called materialistic view, but to the writer it seems an erroneous
one, and it is certainly one that is not proven. It is not even certain
that every planet generated all the gases of its own atmosphere: some
of them it may have swept up in its excursion through space. What is
certain is that it possesses the power of retaining an atmosphere; it
is by no means so certain how all the constituents of that atmosphere
arrived.
_Questions concerning the Origin and Nature of Life._
All that we have actually experienced and verified is that a complex
molecular aggregate is capable of being the vehicle or material basis
of life; but to the question _what life is_ we have as yet no answer.
Many have been the attempts to generate life _de novo_, by packing
together suitable materials and keeping them pleasantly warm for a long
time; but, if all germs of pre-existing life are rigorously excluded,
the attempt hitherto has been a failure: so far, no life has made its
appearance under observation, except from antecedent life.
But, to exclude all trace of antecedent life, it is necessary not only
to shut out floating germs, but to kill all germs previously existing
in the material we are dealing with. This killing of previous life is
usually accomplished by heat; but it has been argued that strong heat
will destroy not only the life but the potentiality for life, will
break up the complex aggregate on which life depends, will deprive the
incubating solution not only of life but of livelihood. There is some
force in the objection, and it is an illustration of the difficulty
surrounding the subject. But Tyndall showed that antecedent life could
be destroyed, without any very high temperature, by gentle heat
periodically applied: heat insufficient to kill the germs, but
sufficient to kill the hatched or developed organisms. Periodic heating
enables the germs of successive ages to hatch, so to speak, and the
product to be slain; and, although some each time may have reproduced
germs before slaughter—eggs capable of standing the warmth—yet a
succession of such warmings would ultimately be fatal to all, and that
without necessarily breaking up the protoplasmic complex aggregates on
the existence of which the whole vital potentiality depends.
So far, however, all effort at spontaneous generation has been a
failure; possibly because some essential ingredient or condition was
omitted, possibly because great lapse of time was necessary. But
suppose it was successful; what then? We should then be reproducing in
the laboratory a process that must at some past age have occurred on
the earth; for at one time the earth was certainly hot and molten and
inorganic, whereas now it swarms with life.
Does that show that the earth generated the life? By no means; no more
than it need necessarily have generated all the gases of its
atmosphere, or the meteoric dust which lies upon its snows.
Life may be something not only ultra-terrestrial, but even immaterial,
something outside our present categories of matter and energy; as real
as they are, but different, and utilising them for its own purpose.
What is certain is that life possesses the power of vitalising the
complex material aggregates which exist on this planet, and of
utilising their energies for a time to display itself amid terrestrial
surroundings; and then it seems to disappear or evaporate whence it
came. It is perpetually arriving and perpetually disappearing. While it
is here, if it is at a sufficiently high level, the animated material
body moves about and strives after many objects, some worthy, some
unworthy; it acquires thereby a certain individuality, a certain
character. It may realise _itself_, moreover, becoming conscious of
its own mental and spiritual existence; and it then begins to explore
the Mind which, like its own, it conceives must underlie the material
fabric—half displayed, half concealed, by the environment, and
intelligible only to a kindred spirit. Thus the scheme of law and
order dimly dawns upon the nascent soul, and it begins to form clear
conceptions of truth, goodness, and beauty; it may achieve something
of permanent value, as a work of art or of literature; it may enter
regions of emotion and may evolve ideas of the loftiest kind; it may
degrade itself below the beasts, or it may soar till it is almost
divine.
Is it the material molecular aggregate that has of its own unaided
latent power generated this individuality, acquired this character,
felt these emotions, evolved these ideas? There are some who try to
think that it is. There are others who recognise in this extraordinary
development a contact between this material frame of things and a
universe higher and other than anything known to our senses; a universe
not dominated by Physics and Chemistry, but utilising the interactions
of matter for its own purposes; a universe where the human spirit is
more at home than it is among these temporary collocations of atoms; a
universe capable of infinite development, of noble contemplation, and
of lofty joy, long after this planet—nay, the whole solar system—shall
have fulfilled its present spire of destiny, and retired cold and
lifeless upon its endless way.
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