simplest rustic observer is struck by the resemblance which the examples
of it left upon a window by frost bear to vegetable forms. In some
crystallizations the mimicry is beautiful and complete; for example, in
the well-known one called the _Arbor Dianæ_. An amalgam of four parts of
silver and two of mercury being dissolved in nitric acid, and water equal
to thirty weights of the metals being added, a small piece of soft
amalgam of silver suspended in the solution, quickly gathers to itself
the particles of the silver of the amalgam, which form upon it a
_crystallization precisely resembling a shrub_. The experiment may be
varied in a way which serves better to detect the influence of
electricity in such operations, as noted below. {166} Vegetable figures
are also presented in some of the most ordinary appearances of the
electric fluid. In the marks caused by positive electricity, or which it
leaves in its passage, we see the ramifications of a tree, as well as of
its individual leaves; those of the negative, recal the bulbous or the
spreading root, according as they are clumped or divergent. These
phenomena seem to say that the electric energies have had something to do
in determining the forms of plants. That they are intimately connected
with vegetable life is indubitable, for germination will not proceed in
water charged with negative electricity, while water charged positively
greatly favours it; and a garden sensibly increases in luxuriance, when a
number of conducting rods are made to terminate in branches over its
beds. With regard to the resemblance of the ramifications of the
branches and leaves of plants to the traces of the positive electricity,
and that of the roots to the negative, it is a circumstance calling for
especial remark, that the atmosphere, particularly its lower strata, is
generally charged positively, while the earth is always charged
negatively. The correspondence here is curious. A plant thus appears as
a thing formed on the basis of a natural electrical operation—the _brush_
realized. We can thus suppose the various forms of plants as,
immediately, the result of a law in electricity variously affecting them
according to their organic character, or respective germinal
constituents. In the poplar, the brush is unusually vertical, and little
divergent; the reverse in the beech: in the palm, a pencil has proceeded
straight up for a certain distance, radiates there, and turns outwards
and downwards; and so on. We can here see at least traces of secondary
means by which the Almighty Deviser might establish all the vegetable
forms with which the earth is overspread.
Vegetable and animal bodies are mainly composed of the same four simple
substances or elements—carbon, oxygen, hydrogen, and nitrogen. The first
combinations of these in animals are into what are called proximate
principles, as albumen, fibrin, urea, alantoin, &c., out of which the
structure of the animal body is composed. Now the chemist, by the
association of two parts oxygen, four hydrogen, two carbon, and two
nitrogen, can _make urea_. Alantoin has also been produced artificially.
Two of the proximate principles being realizable by human care, the
possibility of realizing or forming all is established. Thus the chemist
may be said to have it in his power to realize the first step in
organization. {169a} Indeed, it is fully acknowledged by Dr. Daubeny,
that in the combinations forming the proximate principles there is no
chemical peculiarity. “It is now certain,” he says, “that the same
simple laws of composition pervade the whole creation; and that, if the
organic chemist only takes the requisite precautions to avoid resolving
into their ultimate elements the proximate principles upon which he
operates, the results of his analysis will shew that they are combined
precisely according to the same plan as the elements of mineral bodies
are known to be.” {169b} A particular fact is here worthy of attention.
“The conversion of fecula into sugar, as one of the ordinary processes of
vegetable economy, is effected by the production of a secretion termed
_diastose_, which occasions both the rupture of the starch vesicles, and
the change of their contained gum into sugar. This diastose may be
separately obtained by the chemist, and it acts as effectually in his
laboratory as in the vegetable organization. He can also imitate its
effects by other chemical agents.” {170} The writer quoted below adds,
“No reasonable ground has yet been adduced for supposing that, if we had
the power of bringing together the elements of any organic compound, in
their requisite states and proportions, the result would be any other
than that which is found in the living body.”
It is much to know the elements out of which organic bodies are composed.
It is something more to know their first combinations, and that these are
simply chemical. How these combinations are associated in the structure
of living bodies is the next inquiry, but it is one to which as yet no
satisfactory answer can be given. The investigation of the minutiæ of
organic structure by the microscope is of such recent origin, that its
results cannot be expected to be very clear. Some facts, however, are
worthy of attention with regard to the present inquiry. It is
ascertained that the basis of all vegetable and animal substances
consists of nucleated cells; that is, cells having granules within them.
Nutriment is converted into these before being assimilated by the system.
The tissues are formed from them. The ovum destined to become a new
creature, is originally only a cell with a contained granule. We see it
acting this reproductive part in the simplest manner in the cryptogamic
plants. “The parent cell, arrived at maturity by the exercise of its
organic functions, bursts, and liberates its contained granules. These,
at once thrown upon their own resources, and entirely dependent for their
nutrition on the surrounding elements, develop themselves into new cells,
which repeat the life of their original. Amongst the higher tribes of
the cryptogamia, the reproductive cell does not burst, but the first
cells of the new structure are developed within it, and these gradually
extend, by a similar process of multiplication, into that primary
leaf-like expansion which is the first formed structure in all plants.”
{171} _Here the little cell becomes directly a plant_, _the full formed
living being_. It is also worthy of remark that, in the sponges, (an
animal form,) a gemmule detached from the body of the parent, and
trusting for sustentation only to the fluid into which it has been cast,
becomes, without further process, the new creature. Further, it has been
recently discovered by means of the microscope, that there is, as far as
can be judged, a perfect resemblance between the ovum of the mammal
tribes, during that early stage when it is passing through the oviduct,
and the young of the infusory animalcules. One of the most remarkable of
these, the _volvox globator_, has exactly the form of the germ which,
after passing through a long fœtal progress, becomes a complete mammifer,
an animal of the highest class. It has even been found that both are
alike provided with those _cilia_, which, producing a revolving motion,
or its appearance, is partly the cause of the name given to this
animalcule. These resemblances are the more entitled to notice, that
they were made by various observers, distant from each other at the time.
{172} It has likewise been noted that the globules of the blood are
reproduced by the expansion of contained granules; they are, in short,
_distinct organisms multiplied by the same fissiparous generation_. So
that all animated nature may be said to be based on this mode of origin;
_the fundamental form of organic being is a globule_, _having a new
globule forming within itself_, by which it is in time discharged, and
which is again followed by another and another, in endless succession.
It is of course obvious that, if these globules could be produced by any
process from inorganic elements, we should be entitled to say that the
fact of a transit from the inorganic into the organic had been witnessed
in that instance; the possibility of the commencement of animated
creation by the ordinary laws of nature might be considered as
established. Now it was given out some years ago by a French
physiologist, that _globules could be produced in albumen by
electricity_. If, therefore, these globules be identical with the cells
which are now held to be reproductive, it might be said that the
production of albumen by artificial means is the only step in the process
wanting. This has not yet been effected; but it is known to be only a
chemical process, the mode of which may be any day discovered in the
laboratory, and two compounds perfectly co-ordinate, urea and alantoin,
have actually been produced.
In such an investigation as the present, it is not unworthy of notice
that the production of shell is a natural operation which can be
precisely imitated artificially. Such an incrustation takes place on
both the outside and inside of the wheel in a bleaching establishment, in
which cotton cloth is rinsed free of the lime employed in its
purification. From the _dressing_ employed by the weaver, the cloth
obtains the animal matter, _gelatin_; this and the lime form the
constituents of the incrustation, exactly as in natural shell. In the
wheel employed at Catrine, in Ayrshire, where the phenomenon was first
observed by the eye of science, it had required ten years to produce a
coating the tenth of an inch in thickness. This incrustation has all the
characters of shell, displaying a highly polished surface, beautifully
iridescent, and, when broken, a foliated texture. The examination of it
has even thrown some light on the character and mode of formation of
natural shell. “The plates into which the substance is divisible have
been formed in succession, and certain intervals of time have elapsed
between their formation; in general, every two contiguous laminæ are
separated by a thin iridescent film, varying from the three to the fifty
millionth part of an inch in thickness, and producing all the various
colours of thin plates which correspond to intermediate thicknesses:
between some of the laminæ no such film exists, probably in consequence
of the interval of time between their formation being too short; and
between others the film has been formed of unequal thickness. There can
be no doubt that these iridescent films are formed when the dash-wheel is
at rest during the night, and that when no film exists between two
laminæ, an interval too short for its formation, (arising, perhaps, from
the stopping of the work during the day,) has elapsed during the drying
or induration of one lamina and the deposition of another.” {175} From
this it has been deduced, by a patient investigation, that those colours
of mother-of-pearl, which are incommunicable to wax, arise from
iridescent films deposited between the laminæ of its structure, and it is
hence inferred that _the animal_, like the wheel, _rests periodically
from its labours in forming the natural substance_.
These, it will be owned, are curious and not irrelevant facts; but it
will be asked what actual experience says respecting the origination of
life. Are there, it will be said, any authentic instances of either
plants or animals, of however humble and simple a kind, having come into
existence otherwise than in the ordinary way of generation, since the
time of which geology forms the record? It may be answered, that the
negative of this question could not be by any means formidable to the
doctrine of law-creation, seeing that the conditions necessary for the
operation of the supposed life-creating laws may not have existed within
record to any great extent. On the other hand, as we see the physical
laws of early times still acting with more or less force, it might not be
unreasonable to expect that we should still see some remnants, or partial
and occasional workings of the life-creating energy amidst a system of
things generally stable and at rest. Are there, then, any such remnants
to be traced in our own day, or during man’s existence upon earth? If
there be, it clearly would form a strong evidence in favour of the
doctrine, as what now takes place upon a confined scale and in a
comparatively casual manner may have formerly taken place on a great
scale, and as the proper and eternity-destined means of supplying a
vacant globe with suitable tenants. It will at the same time be observed
that, the earth being now supplied with both kinds of tenants in great
abundance, we only could expect to find the life-originating power at
work in some very special and extraordinary circumstances, and probably
only in the inferior and obscurer departments of the vegetable and animal
kingdoms.
Perhaps, if the question were asked of ten men of approved reputation in
science, nine out of the number would answer in the negative. This is
because, in a great number of instances where the superficial observers
of former times assumed a non-generative origin for life, (as in the
celebrated case in Virgil’s fourth Georgic,) either the direct contrary
has been ascertained, or exhaustive experiments have left no alternative
from the conclusion that ordinary generation did take place, albeit in a
manner which escapes observation. Finding that an erroneous assumption
has been formed in many cases, modern inquirers have not hesitated to
assume that there can be no case in which generation is not concerned; an
assumption not only unwarranted by, but directly opposed to, the
principles of philosophical investigation. Yet this is truly the point
at which the question now rests in the scientific world.
I have no wish here to enter largely into a subject so wide and so full
of difficulties; but I may remark, that the explanations usually
suggested where life takes its rise without apparent generative means,
always appear to me to partake much of the fallacy of the _petitio
principii_. When, for instance, lime is laid down upon a piece of waste
moss ground, and a crop of white clover for which no seeds were sown is
the consequence, the explanation that the seeds have been dormant there
for an unknown time, and were stimulated into germination when the lime
produced the appropriate circumstances, appears extremely unsatisfactory,
especially when we know that (as in an authentic case under my notice)
the spot is many miles from where clover is cultivated, and that there is
nothing for six feet below but pure peat moss, clover seeds being,
moreover, known to be too heavy to be transported, as many other seeds
are, by the winds. Mushrooms, we know, can be propagated by their seed;
but another mode of raising them, well known to the gardener, is to mix
cow and horse dung together, and thus form a bed in which they are
expected to grow without any seed being planted. It is assumed that the
seeds are carried by the atmosphere, unperceived by us, and, finding here
an appropriate field for germination, germinate accordingly; but this is
only assumption, and though designed to be on the side of a severe
philosophy, in reality makes a pretty large demand on credulity. There
are several persons eminent in science who profess at least to find great
difficulties in accepting the doctrine of invariable generation. One of
these, in the work noted below, {179a} has stated several considerations
arising from analogical reasoning, which appear to him to throw the
balance of evidence in favour of the aboriginal production of infusoria,
{179b} the vegetation called mould, and the like. One seems to be of
great force; namely, that the animalcules, which are supposed (altogether
hypothetically) to be produced by ova, are afterwards found increasing
their numbers, not by that mode at all, but by division of their bodies.
If it be the nature of these creatures to propagate in this splitting or
fissiparous manner, how could they be communicated to a vegetable
infusion? Another fact of very high importance is presented in the
following terms:—“The nature of the animalcule, or vegetable production,
bears a constant relation to the state of the infusion, so that, in
similar circumstances, the same are always produced without this being
influenced by the atmosphere. There seems to be a certain _progressive
advance in the productive powers of the infusion_, for at the first the
animalcules are only of the smaller kinds, or monades, and afterwards
_they become gradually larger and more complicated in their structure_;
_after a time_, _the production ceases_, _although the materials are by
no means exhausted_. When the quantity of water is very small, and the
organic matter abundant, the production is usually of a vegetable nature;
when there is much water, animalcules are more frequently produced.” It
has been shewn by the opponents of this theory, that when a vegetable
infusion is debarred from the contact of the atmosphere, by being closely
sealed up or covered with a layer of oil, no animalcules are produced;
but it has been said, on the other hand, that the exclusion of the air
may prevent some simple condition necessary for the aboriginal
development of life—and nothing is more likely. Perhaps the prevailing
doctrine is in nothing placed in greater difficulties than it is with
regard to the entozoa, or creatures which live within the bodies of
others. These creatures do, and apparently can, live nowhere else than
in the interior of other living bodies, where they generally take up
their abode in the viscera, but also sometimes in the chambers of the
eye, the interior of the brain, the serous sacs, and other places having
no communication from without. Some are viviparous, others oviparous.
Of the latter it cannot reasonably be supposed that the ova ever pass
through the medium of the air, or through the blood-vessels, for they are
too heavy for the one transit, and too large for the other. Of the
former, it cannot be conceived how they pass into young animals—certainly
not by communication from the parent, for it has often been found that
entozoa do not appear in certain generations, and some of peculiar and
noted character have only appeared at rare intervals, and in very
extraordinary circumstances. A candid view of the less popular doctrine,
as to the origin of this humble form of life, is taken by a distinguished
living naturalist. “To explain the beginning of these worms within the
human body, on the common doctrine that all created beings proceed from
their likes, or a primordial egg, is so difficult, that the moderns have
been driven to speculate, as our fathers did, on their spontaneous birth;
but they have received the hypothesis with some modification. Thus it is
not from putrefaction or fermentation that the entozoa are born, for both
of these processes are rather fatal to their existence, but from the
aggregation and fit apposition of matter which is already organized, or
has been thrown from organized surfaces. Their origin in this manner is
not more wonderful or more inexplicable than that of many of the inferior
animals from sections of themselves. * * Particles of matter fitted by
digestion, and their transmission through a living body, for immediate
assimilation with it, or flakes of lymph detached from surfaces already
organized, seem neither to exceed nor fall below that simplicity of
structure which favours this wonderful development; and the supposition
that, like morsels of a planaria, they may also, when retained in contact
with living parts, and in other favourable circumstances, continue to
live and be gradually changed into creatures of analogous conformation,
is surely not so absurd as to be brought into comparison with the
Metamorphoses of Ovid. * * We think the hypothesis is also supported in
some degree by the fact, that the origin of the entozoa is favoured by
all causes which tend to disturb the equality between the secerning and
absorbent systems.” {182} Here particles of organized matter are
suggested as the germinal origin of distinct and fully organized animals,
many of which have a highly developed reproductive system. How near such
particles must be to the inorganic form of matter may be judged from what
has been said within the last few pages. If, then, this view of the
production of entozoa be received, it must be held as in no small degree
favourable to the general doctrine of an organic creation by law.
There is another series of facts, akin to the above, and which deserve
not less attention. The pig, in its domestic state, is subject to the
attacks of a hydatid, from which the wild animal is free; hence the
disease called measles in pork. The domestication of the pig is of
course an event subsequent to the origin of man; indeed, comparatively
speaking, a recent event. Whence, then, the first progenitor of this
hydatid? So also there is a tinea which attacks dressed wool, but never
touches it in its unwashed state. A particular insect disdains all food
but chocolate, and the larva of the _oinopota cellaris_ lives nowhere but
in wine and beer, all of these being articles manufactured by man. There
is likewise a creature called the _pimelodes cyclopum_, which is only
found in subterranean cavities connected with certain specimens of the
volcanic formation in South America, dating from a time posterior to the
arrangements of the earth for our species. Whence the first pymelodes
cyclopum? Will it, to a geologist, appear irrational to suppose that,
just as the pterodactyle was added in the era of the new red sandstone,
when the earth had become suited for such a creature, so may these
creatures have been added when media suitable for their existence arose,
and that such phenomena may take place any day, the only cause for their
taking place seldom being the rarity of the rise of new physical
conditions on a globe which seems to have already undergone the principal
part of its destined mutations?
Between such isolated facts and the greater changes which attended
various geological eras, it is not easy to see any difference, besides
simply that of the scale on which the respective phenomena took place, as
the throwing off of one copy from an engraved plate is exactly the same
process as that by which a thousand are thrown off. Nothing is more easy
to conceive than that to Creative Providence, the numbers of such
phenomena, the time when, and the circumstances under which they take
place, are indifferent matters. The Eternal One has arranged for
everything beforehand, and trusted all to the operation of the laws of
his appointment, himself being ever present in all things. We can even
conceive that man, in his many doings upon the surface of the earth, may
occasionally, without his being aware of it, or otherwise, act as an
instrument in preparing the association of conditions under which the
creative laws work; and perhaps some instances of his having acted as
such an instrument have actually occurred in our own time.
I allude, of course, to the experiments conducted a few years ago by Mr.
Crosse, which seemed to result in the production of a heretofore unknown
species of insect in considerable numbers. Various causes have prevented
these experiments and their results from receiving candid treatment, but
they may perhaps be yet found to have opened up a new and most
interesting chapter of nature’s mysteries. Mr. Crosse was pursuing some
experiments in crystallization, causing a powerful voltaic battery to
operate upon a saturated solution of silicate of potash, when the insects
unexpectedly made their appearance. He afterwards tried nitrate of
copper, which is a deadly poison, and from that fluid also did live
insects emerge. Discouraged by the reception of his experiments, Mr.
Crosse soon discontinued them; but they were some years after pursued by
Mr. Weekes, of Sandwich, with precisely the same results. This
gentleman, besides trying the first of the above substances, employed
ferro-cyanet of potash, on account of its containing a larger proportion
of carbon, the principal element of organic bodies; and from this
substance the insects were produced _in increased numbers_. A few weeks
sufficed for this experiment, with the powerful battery of Mr. Crosse;
but the first attempts of Mr. Weekes required about eleven months, a
ground of presumption in itself that the electricity was chiefly
concerned in the phenomenon. The changes undergone by the fluid operated
upon, were in both cases remarkable, and nearly alike. In Mr. Weekes’
apparatus, the silicate of potash became first turbid, then of a milky
appearance; round the negative wire of the battery, dipped into the
fluid, there gathered a quantity of _gelatinous matter_, a part of the
process of considerable importance, considering that gelatin is one of
the _proximate principles_, or first compounds, of which animal bodies
are formed. From this matter Mr. Weekes observed one of the insects in
the very act of emerging, immediately after which, it ascended to the
surface of the fluid, and sought concealment in an obscure corner of the
apparatus. The insects produced by both experimentalists seem to have
been the same, a species of acarus, minute and semi-transparent, and
furnished with long bristles, which can only be seen by the aid of the
microscope. It is worthy of remark, that some of these insects, soon
after their existence had commenced, were found to be likely to extend
their species. They were sometimes observed to go back to the fluid to
feed, and occasionally they devoured each other. {187}