ORIGIN OF BRUTE MATTER IN LIVING MATTER.
Spontaneous generation: an episode in the history of the
globe—Verification of the identity between brute and living
matter—Slow identification—Rapid identification—Contrary
opinion—Hypothesis of cosmozoa; cosmic panspermia—Hypothesis of
pyrozoa.
There should be two ways of testing the doctrine of the essential
identity of brute and living matter—one slow and more laborious, the
other more rapid and decisive.
_Identification of the Two Matters, Brute and Living._—The laborious
method, which we will be obliged to follow, consists in the attentive
examination of the various activities by which life is manifested, and
in finding more or less crude equivalents for them in all brute beings,
or in certain of them.
_Rapid Verification. Spontaneous Generation._—The rapid and decisive
method, which, unhappily, is beyond our resources, would consist in
showing unquestionable, clearly marked life, the superior life, arising
from the kind of inferior life that is attributed to matter in general.
It would be necessary completely to construct in all its parts, by a
suitable combination of inorganic materials, a single living being,
even the humblest plant or the most rudimentary animal. This would
indeed be an irrefutable proof that the germs of all vital activity are
contained in the molecular activity of brute bodies, and that there is
nothing essential to the latter that is not found in the former.
Unhappily this demonstration cannot be given. Science furnishes no
example of it, and we are forced to have recourse to the slow method.
The question here involved is that of spontaneous generation. It is
well known that the ancients believed in spontaneous generation,
even for animals high in the scale of organization. According to Van
Helmont, mice could be born by some incomprehensible fermentation in
dirty linen mixed with wheat. Diodorus speaks of animal forms which
were seen to emerge, partly developed, from the mud of the Nile.
Aristotle believed in the spontaneous birth of certain fishes. This
belief, though rejected as to the higher forms, was for a long time
held with regard to the lower forms of animals, and to insects—such as
the bees which the shepherd of Virgil saw coming out from the flanks
of the dead bullock—flies engendered in putrefying meat, fruit worms
and intestinal worms; finally, with regard to infusoria and the most
rudimentary vegetables. The hypothesis of the spontaneous generation of
the living being at the expense of the materials of the ambient medium
has been successively driven from one classificatory group to another.
The history of the sciences of observation is also a history of the
confutation of this theory. Pasteur gave it the finishing stroke, when
he showed that the simplest microorganisms obeyed the general law which
declares that the living being is formed only by _filiation_—that is
to say, by the intervention of a pre-existing living organism.
_Spontaneous Generation an Episode in the History of the Globe._—Though
we have been unable to effect spontaneous generation up to the present,
it has been referred by Haeckel to a more or less distant past, to
the time when the cooling of the globe, the solidification of its
crust, and the condensation of aqueous vapour upon its surface created
conditions compatible with the existence of living beings similar
to those with which we are acquainted. Lord Kelvin has fixed these
geological events as occurring from twenty to forty million years ago.
Then circumstances became propitious for the appearance of the first
organisms, whence were successively derived those which now people the
earth and the waters.
Circumstances favourable to the appearance of the first beings
apparently occurred only in a far distant past; but most physiologists
admit that if we knew exactly these circumstances, and could reproduce
them, we might also expect to produce their effect—namely, the creation
of a living being, formed in all its parts, developed from the
inorganic kingdom. To all those who held this view the impotence of
experiment at the present time is purely temporary. It is comparable to
that of primitive men before the time of Prometheus; they, not knowing
how to produce fire, could only get it by transmitting it from one to
another. It is due to the inadequacy of our knowledge and the weakness
of our means; it does not contradict the possibility of the fact.
_Contrary Opinion. Life did not Originate on our Globe._—But all
biologists do not share this opinion. Some, and not the least eminent,
hold it to be an established fact that it is impossible for life to
arise from a concurrence of inorganic materials and forces. This was
the opinion of Ferdinand Cohn, the great botanist; of H. Richter, the
Saxon physician, and of W. Preyer, a physiologist well known from his
remarkable researches in biological chemistry. According to these
scientists, life on the surface of the globe cannot have appeared as a
result of the reactions of brute matter and the forces that continue to
control it.
According to F. Cohn and PI. Richter, life had no beginning on our
planet. It was transported to the earth from another world, from the
cosmic medium, under the form of cosmic germs, or _cosmozoa_, more
or less comparable to the living cells with which we are acquainted.
They may have made the journey either enclosed in meteorites, or
floating in space in the form of cosmic dust. The theory in question
has been presented in two forms:—_The Hypothesis of Meteoric Cosmozoa_,
by a French writer, the Count de Salles-Guyon; and that of _cosmic
panspermia_ brought forward in 1865 and 1872 by F. Cohn and H. Richter.
_Hypothesis of the Cosmozoa._—The hypothesis of the cosmozoa, living
particles, protoplasmic germs emanating from other worlds and reaching
the earth by means of aerolites, is not so destitute of probability
as one might at first suppose. Lord Kelvin and Helmholtz gave it the
support of their high authority. Spectrum analysis shows in cometary
nebulæ the four or five lines characteristic of hydro-carbons. Cosmic
matter, therefore, contains compounds of carbon, substances that are
especially typical of organic chemistry. Besides, carbon and a sort
of humus have been found in several meteorites. To the objection
that these aerolites are heated while passing through our atmosphere,
Helmholtz replies that this elevation of temperature may be quite
superficial and may allow micro-organisms to subsist in their interior.
But other objections retain their force:—First, that of M. Verworn, who
considers the hypothesis of cosmic germs as inconsistent with the laws
of evolution; and that of L. Errera, who denies that the conditions
necessary for life exist in interplanetary bodies.
_Hypothesis of Cosmic Panspermia._—Du Bois-Reymond has given the name
of _cosmic panspermia_ to a theory very similar to the preceding,
formulated by F. Cohn in 1872. The first living germs arrived on our
globe mingled with the cosmic dust that floats in space and falls
slowly to the surface of the earth. L. Errera observes that if they
escape by this gentle fall the dangerous heating of meteorites, they
still remain exposed to the action of the photic rays, which is
generally destructive to germs.
_Hypothesis of Pyrozoa._—W. Preyer declined to accept this cosmic
transmigration of the simplest living beings, nor would he allow
the intervention of other worlds into the history of our own. Life,
according to him, must have existed from all time, even when the globe
was an incandescent mass. But it was not the same life as at present.
Vitality must have undergone many profound changes in the course of
ages. The _pyrozoa_, the first living beings, vulcanians, were very
different from the beings of the present day that are destroyed by
a slight elevation of temperature. No doubt this theory of pyrozoa,
proposed by W. Preyer in 1872, seems quite chimerical, and akin
to Kepler’s dreamy visions. But in a certain way it accords with
contemporary ideas concerning the life of _matter_. It is related
to them by the evolution which it implies in the materials of the
terrestrial globe.
According to Preyer, primitive life existed in fire. Being igneous
masses in fusion, the pyrozoa lived after their own manner; their
vitality, slowly modified, assumed the form which it presents to-day.
Yet, in this profound transformation their number has not varied, and
the total quantity of life in the universe has remained unchanged.
Here we recognize the ideas of Buffon. These cosmozoa, these pyrozoa,
have a singular resemblance to the _organic molecules_ of “live matter”
of the illustrious naturalist—distributed everywhere, indestructible,
and forming living structures by their concentration.
But we must leave these scientific or philosophical theories, and come
to arguments based upon facts.
It is in a spirit quite different from that of the poets, the
metaphysicians, and the more or less philosophical scientists that
the science of our days looks at the more or less obscure vitality of
inanimate bodies. It claims that we may recognize in them, in a more or
less rudimentary state, the action of the factors which intervene in
the case of living beings, the manifestation of the same fundamental
properties.