PHENOMENA OF ANIMAL LIFE.
Distinction between the Kingdoms of Nature--Progress of Animal
Life--Sponges--Polypes--Infusoria--Animalcula--Phosphorescent
Animals--Annelidans--Myriapoda--Animal
Metamorphoses--Fishes--Birds--Mammalia--Nervous System--Animal
Electricity--Chemical Influences--Influence of Light on Animal
Life--Animal Heat--Mechanical Action--Nervous Excitement--Man and
the Animal Races, &c.
“A stone grows; plants grow and live; animals grow, live, and feel.”
Such were the distinctions made by Linnæus, between the conditions
of the three kingdoms of nature. We cannot, however, but regard them
as in all respects illogical. The stone--a solid mass of unorganized
particles--enlarges, if placed in suitable conditions, by the accretion
of other similar particles around it; but it does not, according to any
meaning in which we use the word, _grow_. Plants and animals grow; and
they differ, probably, only in the phenomena of sensation. Yet, the
trembling mimosa, and several other plants, appear to possess as much
feeling as sponges and some of the lower classes of animals. By this
definition, however, of the celebrated Swedish naturalist, we have a
popular and simple expression of a great fact.
As we have only to examine the question of the agency of the physical
forces upon animal life, we must necessarily confine our attention to
the more striking phenomena with which science has made us acquainted;
and, having briefly traced the apparent order in which the advance of
organization proceeded, we must direct our few concluding remarks to
the physico-physiological influences, which we must confess to know but
too imperfectly.
We learn that, during the states of progress which geology, looking
into the arcana of time, has made us acquainted with, a great variety
of animal forms were brought into existence. They lived their periods.
The conditions of the surface of the earth, the sea, or the atmosphere,
were altered; and, no longer fitted for the enjoyments of the new life,
these races passed away, and others occupied their places, which, in
turn, went through all the stages of growth, maturity, and decay;
until at length, the earth being constituted for the abode of the
highest order of animals, they were called into existence; and man,
the intellectual monarch of the world, was placed supreme amongst them
all. Types of nearly all those forms of life which are found in the
fossil state are now in existence; and if we examine the geographical
distribution of animals--the zones of elevation over the surface of
the earth, and the zones of depth in the ocean,--we shall find, now
existing, animal creations strikingly analogous to the primitive forms
and conditions of the earth’s inhabitants. From the depths of the ocean
we may even now study--as that most indefatigable naturalist, Professor
Edward Forbes, has done--the varying states of organization under the
circumstances of imperfect light and varying temperature.[261]
The gradual advance of animal life in the ascending strata has led
to many speculations, ingenious and refined, on the progressive
development of animals. That the changes of the inorganic world have
impressed new conditions on the organic structures of animals, to meet
the necessities of their being, must be admitted. Comparative anatomy
has demonstrated that such supposed differences really existed between
the creatures of secondary formations--those of the tertiary and the
present periods. It has been imagined, but upon debatable foundations,
that the atmosphere, during the secondary periods, was highly charged
with carbonic acid; and, consequently, that though beneficial to the
growth of plants, and peculiarly fitted for the conditions required
by those which the fossil flora makes us acquainted with, it was not
adapted to support any animals above the slow-breathing, cold-blooded
fishes and reptiles. Under the action of the super-luxuriant vegetation
of these periods, this carbonic acid is supposed to have been removed,
an addition of oxygen furnished; and thus, consequently, the earth
gradually fitted for the abode of warm-blooded and quick-breathing
creatures. We do, indeed, find a very marked line between the fossil
remains of the lias formations which enclose the saurians, and the
wealden, in which birds make their appearance more numerously than in
any previous formation.
Founded upon these facts, speculations have been put forth on the
gradual development of animals from the lowest up to the highest
orders. Between the polype and man a continuous series has been
imagined, every link of the chain being traced into connection with
the one immediately succeeding it; and, through all the divisions,
zoophytes, fishes, amphibia, reptiles, birds, and mammalia are seen,
according to this hypothesis, to be derived by gradual advancement from
the preceding orders. The first having given rise to amphibia,--the
amphibion gives birth to the reptile,--the reptile advances to
the bird,--and from this class is developed the mammal. A slight
investigation will convince us that this view has no foundation.
Although a certain relationship may be found between some of the
members of one class, and those of the other immediately joining it,
yet this is equally discovered to exist towards classes more remote
from each other; and in no one instance can we detect anything like
the passage of an animal of one class into an animal of another. Until
this is done, we cannot but regard the forms of animal life as distinct
creations, each one fitted for its state of being, springing from the
command of the great First Cause.[262]
But it is time to quit these speculative questions, and proceed to the
examination of the general conditions of animal life at the present
time.
Lowest in the scale of animals, and scarcely distinguishable from a
vegetable, we find the sponge, attached to and passing its life upon
a rock, exhibiting, indeed, less signs of feeling than many of the
vegetable tribes. The chemical differences between vegetables and
sponges are, however, very decided; and we find in the tissues of the
sponge a large quantity of nitrogen, a true animal element, which
exists, but in smaller quantities, in vegetables.
These creations, standing between vegetable and animal life, possess
the singular power of decomposing carbonic acid, as plants do; and the
water in which they live always contains an excess of free oxygen.
The polypes are a remarkably curious class. “Fixed in large arborescent
masses to the rocks of tropical seas, or in our own climate attached
to shells or other submarine substances, they throw but their
ramifications in a thousand beautiful and plant-like forms; or,
incrusting the rocks at the bottom of the ocean with calcareous earth,
separated from the water which bathes them, they silently build up
reefs and shoals, justly dreaded by the navigator; and sometimes giving
origin, as they rise to the surface of the sea, to islands, which
the lapse of ages clothes with luxuriant verdure, and peoples with
appropriate inhabitants.”[263]
Most of the polypes are fixed and stationary; but the hydra and some
others have the power of changing their positions, which they do in
search of the light of the sun. They do not appear to have organs of
sight requiring light; but still they delight in the solar influences.
The most extraordinary fact connected with the hydra is its being
multiplied by division. If an incision be made in the side of a hydra,
a young polype soon developes itself; and if one of these creatures be
divided, it quickly restores the lost portion of its structure. The
varieties of the polypes are exceedingly numerous, and many of them are
in the highest degree curious, and often very beautiful. The actiniæ,
like flowers, appear to grow from the rocks, unfolding their tentacula
to the light; and, in the excitement due to their eagerness for prey,
they exhibit a beautiful play of colours and most interesting forms.
Microscopic zoophytes of the most curious shapes are found,--all of
which attest, under examination, the perfection of all created things.
Infusoria and animalcula,--animals, many of them, appearing under the
microscope as little more than a transparent jelly,--must be recognized
as the most simple of the forms of life. They exist in all waters in
uncountable myriads; and, minute creatures as they are, it has been
demonstrated that many of the great limestone hills are composed
entirely of their remains.
The acalephæ, or the phosphorescent animals of the ocean, are no less
curious. From creatures of the most minute size, they extend to a
considerable magnitude, yet they appear to be little more than animated
masses of sea-water. If any one of these sea-jellies, or jelly-fishes
as they are often called (even the largest varieties of them), is cast
upon the shore, it is soon, by the influence of the sun, converted into
a mere fibre no thicker than a cobweb: an animal weighing seven or
eight pounds is very soon reduced to as many grains. There are numerous
kinds of these singular creatures, most of which are remarkable for
the powerful phosphorescent light they emit. The _beroes_ and the
_pulmonigrade_ shine with an intense white light many feet below the
surface, whilst the _Cestum Veneris_, or girdle of Venus, gliding
rapidly along, presents, on the edge of the wave, an undulating riband
of flame of considerable length. There can be no doubt that this arises
from the emission of phosphorescent matter of an unknown kind from the
bodies of these animals.
The microscope has made us familiar with the mysteries of a minute
creation which we should not otherwise have comprehended. These
creatures are found inhabiting the waters and the land, and they exist
in the intestinal structure of plants and animals, preying upon the
nutritive juices which pass through their systems. Although these
beings are so exceedingly small that even the most practised observer
cannot detect them with the naked eye, they are proved, by careful
examination under the microscope, to be in many cases elaborately
organized. Ehrenberg has discovered in them filamentary nerves and
nervous masses, and even vessels appropriated to the circulation
of fluids, showing that they belong really to a high condition of
existence.
Passing over many links in that curious chain which appears to bind
the animal kingdom into a complete whole, we come to the articulata of
Cuvier--the homogangliata of Owen.
All those creatures which we have been hitherto considering are too
imperfect in the construction of their simple organizations to maintain
a terrestrial existence; they are, therefore, confined to a watery
medium. In the articulata, we have evidences of higher attributes,
and indications of instincts developed in proportion to the increased
perfection of organization. Commencing with the annelidans, all of
which, except the earthworms, are inhabitants of the waters, we
proceed to the myriapoda, presenting a system intermediate in every
respect between that of worms and insects; we then find embraced in
the same order, the class insecta, which includes flies and beetles
of all kinds; and, as the fourth division of articulated beings, the
arachnidans or spiders; and, lastly, the marine tribe of crustaceans.
The most remarkable phenomena connected with these animals are the
metamorphoses which they undergo. The female butterfly, for instance,
lays eggs, which, when hatched, produce caterpillars: these live in
this state for some time, feeding upon vegetables, and, after casting
their skins as they increase in size, at last assume an entirely
different state, and, dormant in their oblong case, they appear like
dead matter. This chrysalis, or pupa, is generally preserved from
injury by being embedded in the earth, from which, after a season, a
beautifully perfect insect escapes, and, floating on the breeze of
summer, enjoys its sunshine, and revels amidst its flowers.
No less remarkable is the metamorphosis of the caducibranchiate
amphibia, passing through the true fish condition of the tadpole to the
perfect air-breathing and four-footed animal, the frog.
A metamorphosis of the crustaceans, somewhat similar to that which
takes place in insects, has been of late years creating much discussion
amongst naturalists: but the question appears to be now settled by the
careful and long-continued observations of Mr. Thompson and Mr. R. C.
Couch.
A wide line of demarcation marks the separation of the invertebrata
from the four great classes of vertebrate animals--fishes, reptiles,
birds, and mammalia. Every part of the globe,--the ocean and the inland
lake,--the wide and far-winding river, and the babbling stream,--the
mountain and the valley,--the forest with its depth of shade, and
the desert with its intensity of light,--the cold regions of the
frost-chained north, and the fervid clime within the tropics--presents
for our study innumerable animals, each fitted for the conditions to
which it is destined; and through the whole we find a gradual elevation
in the scale of intelligence, until at last, separated from all by
peculiar powers, we arrive at man himself.
In each of these four classes the animals are furnished with a bony
skeleton, which is in the young animal little more than cartilage;
but, as growth increases, lime becomes deposited, and a sufficient
degree of hardness is thus produced to support the adult formation.
Some anatomists have endeavoured to show that even in the mechanical
structure of the bony fabrics of animals, we are enabled to trace a
gradual increase in the perfection of arrangement, from the fish until
the most perfect is found in man. Many of the mammalia, however, are
furnished with skeletons which really surpass that of man. These belong
to animals which depend for subsistence upon their muscular powers, and
with whom man is, in this particular, on no equality. What is the lord
of the creation, compared with the antelope for fleetness, or with the
elephant and many other animals for strength?
As we ascend the scale of animal life we find a more perfectly
developed nervous system; and the relative size of the brain, compared
with that of the brute, is found progressively to increase, until it
arrives at the utmost perfection in man. On the system of nerves
depends sensation, and there can be no doubt that the more exalted the
order of intelligence displayed, the more exquisitely delicate is the
nervous system. Thus, in this world, refined genius must necessarily be
attended with a condition of sensibility which, too frequently, to the
possessor is a state of real disease.
It must be evident to every reader that but very few of the striking
features of animal life have been mentioned in the rapid survey which
has been taken of the progress of animal organization. The subject
is so extensive that it would be quite impossible to embrace it
within any reasonable limits; and it furnishes matter so curious and
so instructive, that, having once entered on it, it would have been
difficult to have made any selection, and we must have devoted a volume
to the æsthetics of natural science. Passing it by, therefore, with the
mere outline which has been given, we must proceed to consider some of
the conditions of vitality.
Bell has proved that one set of nerves is employed in conveying
sensation to the brain, and another set in transferring the desires of
the will to the muscles. By the separation of a main branch of one of
the nerves of sensation, although all the operations of life will still
proceed, the organ to which that nerve goes is dead to its particular
sense. In like manner, if one of the nerves of volition is divided,
the member will not obey the inclination of the brain. It is evident,
therefore, although many of the great phenomena of vital force are
dependent on the nervous system, and the paralysis of a member ensues
upon the separation or the disease of a nerve, that the nerves are but
the channels through which certain influences are carried. The _vis
vitæ_ or vital principle--for we are compelled by the imperfection of
our knowledge to associate under this one term the ultimate causes of
many of the phenomena of life--is a power which, although constantly
employed, has the capability of continually renewing itself by
some inexplicable connection existing between it and many external
influences. We know that certain conditions are necessary to the health
of animals. Diseased digestion, or any interruption in the circulation
of the blood, destroys the vital force, and death ensues. The processes
of digestion and of the circulation are perfectly understood, yet we
are no nearer the great secret of the living principle.
Animals are dependent on several external agents for the support of
existence. The oxygen of the air is necessary for respiration. Animal
heat, as will be shown presently, is in a great measure dependent
upon it. The external heat is so regulated that animal existence is
comfortably supported. Electricity is without doubt an essential
element in the living processes; and, indeed, many physiologists have
been inclined to refer vital force to the development of electricity
by chemical action in the brain. This view has, however, no foundation
in experiment beyond that afforded by the appearance of electric
currents, when the brain is excited. This proves no more than that the
operations of mind develope physical power in the matter with which it
is mysteriously connected.
The phenomena of the Torpedo and Gymnotus we have already noticed,[264]
and there are other creatures which certainly possess the power of
secreting and discharging electricity. Galvani’s experiments, and
those of Aldini, appear to show--and the more delicate researches of
Matteucci have satisfactorily determined--that currents of electricity
are always circulating in the animal frame;--that positive electricity
is constantly passing from the interior to the exterior of a muscle.
Matteucci, by arranging a series of muscles, has formed an electric
pile of some energy.[265] These currents have been detected in man, in
pigeons, fowls, eels, and frogs.
In the human body it is evident a large quantity of electricity
exists in a state of equilibrium. Du Bois Raymond has shown that we
may by mere muscular motion give rise to electric currents which can
be measured by the galvanometer. This, however, may be said of every
substance. It is perhaps more easily disturbed in the human system;
indeed, the manifestation of sparks from the hair and other parts of
the body by friction is not uncommon. Every chemical action, it has
been already shown, gives rise to electrical manifestations; and the
animal body is a laboratory, beautifully fitted with apparatus, in
which nearly every chemical process is going on. It has been proved
that acid and alkaline principles are constantly acting upon each
other through the tissues of the animal frame; and we have the curious
phenomena of endosmose and exosmose in constant effort, and catalysis
or _surface force_, operating in a mysterious manner.[266]
With the refined physiological questions connected with the phenomena
of sensation we cannot deal, nor will any argument be adduced for or
against the hypothesis which would refer these phenomena to some
extraordinary development of electric force in the brain. The entire
subject appears to stand beyond the true limits of science, and every
attempt to pass it is invariably found to lead to a confused mysticism,
in which the real and the ideal are strangely confounded. Science stops
short of the phenomena of vital action.
We cannot, however, but refer to the idea entertained by many that the
brain is an electric battery, and the nerves a system of conductors.
On this view Sir John Herschel remarks:--“If the brain be an electric
pile constantly in action, it may be conceived to discharge itself
at regular intervals, when the tension of the electricity reaches a
certain point, along the nerves which communicate with the heart, and
thus excite the pulsation of that organ.” Priestley, however, appears
to have been the first to promulgate this idea.
Light is an essential element in producing the grand phenomenon of
life, though its action is ill understood. Where there is light,
there is life, and any deprivation of this principle is rapidly
followed by disease of the animal frame, and the destruction of the
mental faculties. We have proof of this in the squalor of those whose
necessities compel them to labour in places to which the blessings
of sunshine never penetrate, as in our coal-mines, where men having
everything necessary for health, except light, exhibit a singularly
unhealthy appearance. The state of fatuity and wretchedness to which
those individuals have been reduced who have been subjected for
years to incarceration in dark dungeons, may be referred to the same
deprivation. Again, in the peculiar aspect of those people who inhabit
different regions of the earth under varying influences of light, we
see evidence of the powerful effects of solar action. Other forces, as
yet undiscovered, may, in all probability do, exert decided influences
on the animal economy; but, although we recognize many effects which we
cannot refer to any known causes, we are perfectly unable to imagine
the sources from which they spring.
It will be interesting now to examine the phenomena of animal heat, the
consideration of which naturally leads us to consider the digestive
system, the circulatory processes, and the effects of nervous
excitation.
The theory, which attributes animal heat to the combination of the
carbon of the food taken into the stomach with the oxygen of the air
inspired through the lungs, has become a very favourite one. It must,
however, be remembered that it is by no means new. The doctrines of
Brown, known as the Brunonian system, and set forth in his _Elementa
Medicinæ_, are founded upon similar hasty generalizations. Although,
without doubt, true in a certain degree, it is not so to the extent
to which its advocates would have us believe. That the carbonaceous
matter received into the stomach, after having undergone the process
of digestion, enters into combination with the oxygen breathed through
the lungs or absorbed by the skin, and is given off from the body in
the form of carbonic acid, and that, during the combination, heat is
produced, by a process similar to that of ordinary combustion, is an
established fact; but the idea of referring animal heat entirely to
this chemical source, when there are other well-known causes producing
calorific effects, is an example of the errors into which an ingenious
mind may be led, when eagerly seeking to establish a favourite
hypothesis.
Animal and vegetable diet, which is composed largely of carbon and
hydrogen, passes into the digestive system, and becomes converted into
the various matters required for the support of the animal structure.
The blood is the principal fluid employed in distributing over the
system the necessary elements of health and vigour, and for restoring
the waste of the body. This fluid, in passing through the lungs,
undergoes a very remarkable change, and not merely assumes a different
colour, but really acquires new properties, from its exposure to the
air with which the cells of these organs are filled. By a true chemical
process, the oxygen is separated from the air, that oxygen is made to
combine with the carbon and hydrogen, and carbonic acid and water are
formed. These are liberated and thrown off from the body either through
the lungs or by the skin. In the processes of life, as far as we are
enabled to trace them, we see actions going on which are referred to
certain causes which we _appear_ to explain. Thus, the combination of
the oxygen of the air with the carbon of the blood is truly designated
a case of chemical affinity; and we find that in endeavouring to
imitate the processes of nature in the laboratory, we are, to a certain
extent, successful. We can combine carbon and oxygen to produce
carbonic acid; and we know that the result of that combination is the
development of certain definite quantities of heat. Let us examine the
conditions of this chemical phenomenon, and we shall find that in the
natural and artificial processes,--for we must be allowed to make that
distinction,--there are analogous circumstances. If we place a piece of
pure carbon, a lump of charcoal or a diamond, in a vessel of air, or
even of pure oxygen gas, no change will take place in either of these
elements, and, however long they may be kept together, they will still
be found as carbon or diamond, and oxygen gas. If we apply heat to the
carbon until it becomes incandescent, it immediately begins to combine
with the oxygen gas,--it burns;--after a little time all the carbon has
disappeared, and we shall find, if the experiment has been properly
made, that a gas is left behind which is distinguished by properties
in every respect the reverse of those of oxygen, supporting neither
life nor combustion, whereas oxygen gives increased vigour to both.
We have now, indeed, carbonic acid gas formed by the union of the two
principles.
A dead mass of animal matter may be placed in oxygen gas, and, unless
some peculiar conditions are in some way brought about, no change will
take place; but, if it were possible to apply the _spark of life_ to
it, as we light up the spark in the other case, or if, as that is
beyond the power of man, we substitute a living creature, a combination
between the carbon of the animal and the gas will immediately begin,
and carbonic acid will be formed by the waste of animal matter, as in
the other case it is by the destruction of the carbon; and, if there is
not a fresh supply given, the animal must die, from the exhaustion of
its fabric. Now, in both these cases, it is clear that, although this
chemical union is a proximate cause of heat, there must be existing
some power superior to it, as the ultimate cause thereof.
The slow combustion (_eremacausis_) of vegetable matter, decomposing
under the influence of moisture and the air, does not present similar
conditions to those of the human body, although it has been insisted
upon to be in every respect analogous. That the results resemble each
other is true, but we must carefully distinguish between effects and
causes; and the results of chemical decomposition in inert matter
differ from those in the living organism. The vegetable matter has lost
the principle of organic life, and, that gone, the tendency of all
things being to be resolved into their most simple forms, a disunion of
the elements commences: oxygen, hydrogen, and carbon pass off either
in the gaseous state or as water, whilst some carbon is liberated in
a very finely-divided condition, and enters slowly into combination
with oxygen supplied by the water or the air. Hydrogenous compounds
are at the same time formed, and, under all these circumstances, as in
all other chemical phenomena, an alteration of temperature results.
Heat results from the chemical changes, and eventually true combustion
begins.
The animal tissue may act in the same way as platina has already
been shown to act in producing combination between gases; but of this
we have no proof. We know that electricity is capable of producing
the required conditions, and we also learn, from the beautiful
researches of Faraday, that the quantity of electricity developed
during decomposition is exactly equal to that required to effect the
combination of the same elements. Thus it is quite clear that, during
the combination of the carbon of the blood with the oxygen of the air,
a large amount of electricity must become latent in the compound. The
source of this we know not: it may be derived from some secret spring
within the living structure, or it may be gathered from the matter
surrounding it. There is much in nervous excitation which appears like
electrical phenomena, and attempts have been frequently made to refer
sensation to the agency of electricity. But these are the dreams of the
ingenious, for which there is but little waking reality.
Every mechanical movement of the body occasions the development of
heat; every exertion of the muscles produces sensible warmth; and,
indeed, it can be shown by experiment that every expansion of muscular
fibre is attended with the escape of caloric, and its contraction
with the absorption of it. There are few operations of the mind which
do not excite the latent caloric of the body, and frequently we find
it manifested in a very remarkable manner by a suddenly-awakened
feeling. The poet, in the pleasure of creation, glows with the ardour
of his mind, and the blush of the innocent is but the exhibition
of the phenomenon under some nervous excitation, produced by a
spirit-disturbing thought. Thus we see that the processes of digestion
and respiration are not the only sources of animal heat, but that many
others exist to which much of the natural temperature of the body must
be referred.
So much that is mysterious belongs to the phenomena of life, that
superstition has had a wide scope for the exercise of its influence;
and through all ages a powerful party of mankind have imagined that
the spirit of human curiosity must be checked before it advances to
remove the veil from any physiological causes. Hence it is that even at
the present day so much that stands between what, in our ignorance, we
call the real and the supernatural, remains uninvestigated. Even those
men whose minds are sceptical upon any development of the truths of
great natural phenomena,--who, at all events, will have proof before
they admit the evidence, are ready to give credit to the grossest
absurdities which may be palmed upon them by ingenious charlatans,
where the subject is man and his relations to the spiritual world.
Man, and the races of animals by which he is surrounded, present a
very striking group, consider them in whatever light we please. The
gradual improvement of organic form, and the consequent increase of
sensibility, and eventually the development of reason, are the grandest
feature of animated creation.
The conditions as to number even of the various classes are not the
least remarkable phenomena of life. In the lowest orders of animals,
creatures of imperfect organization,--consequently those to whom the
conditions of pain must be nearly unknown,--increase by countless
myriads. Of the infusoria and other beings, entire mountains have
been formed, although microscopes of the highest powers are required
to detect an individual. Higher in the scale, even among insects, the
same remarkable conditions of increase are observed. Some silkworms lay
from 1,000 to 2,000 eggs; the wasp deposits 3,000; the ant from 4,000
to 5,000. The queen bee lays between 5,000 and 6,000 eggs according to
Burmeister; but Kirby and Spence state that in one season the number
may amount to 40,000 or 50,000. But, above all, the white ant (_Termes
fatalis_) produces 86,400 eggs each day, which, continuing for a
lunar month, gives the astonishing number of 2,419,200, a number far
exceeding that produced by any known animal.
These may appear like the statements in which a fictionist might
indulge, but they are the sober truths discovered by the most
pains-taking and cautious observers. And it is necessary that such
conditions should prevail. These insects, and all the lower tribes of
the animal kingdom, furnish food for the more elevated races. Thousands
are born in an hour, and millions upon millions perish in a day. For
the support of organic life, like matter is required; and we find that
the creatures who are destined to become the prey of others are so
constituted that they pass from life with a perfect unconsciousness of
suffering. As the animal creation advances in size and strength, their
increase becomes limited; and thus they are prevented from maintaining
by numbers that dominion over the world which they would be enabled
from their powers to do, were their bands more numerous than we now
find them.
The comparative strength, too, of the insect tribes has ever been a
subject of wonder and of admiration to the naturalist. The strength of
these minute creatures is enormous; their muscular power, in relation
to their size, far exceeds that of any other animal. The grasshopper
will spring two hundred times the length of its own body. The
dragonfly, by its strength of wing, will sustain itself in the air for
a long summer day with unabated speed. The house-fly makes six hundred
strokes with its wings, which will carry it five feet, every second.
The stag-beetle, were it the size of the elephant, would be able to
tear up the largest mountains.
Such are the wonders of the natural world; from the zoophyte, growing
like a flowering plant[267] upon an axis filled with living pith--a
small remove from the conditions of vegetable life, upwards through the
myriads of breathing things--to man, we see the dependence of all upon
these physical powers which we have been considering.
To trace the effects of those great causes through all their mysterious
phases is the work of inductive science; and the truths discovered tend
to fit us for the enjoyment of the eternal state of high intelligence
to which every human soul aspires.
That which the ignorant man calls the supernatural, the philosopher
classes amongst natural phenomena. The ideal of the credulous man
becomes the real to him who will bend his mind to the task of inquiry.
Therefore to attempt to advance our knowledge of the unknown, to add
to the stores of truth, is an employment worthy the high destiny of
the human race. Remembering that the revelations of natural science
cannot in any way injure the revelation of eternal truth, but, on
the contrary, aid to establish in the minds of the doubting a firm
conviction of its Divine origin and of man’s high position, we need
never fear that we are proceeding too far with any inquiry, so long as
we are cautious to examine the conditions of our own minds, that they
be not made the dupe of the senses.
In the fairies of the hills and valleys, in the gnomes of the caverns,
in the spirits of the elements, we have the attempts of the mind, when
the world was young, to give form to the dim outshadowings of something
which was then felt to be hidden behind external nature.
In the Oread, the Dryad, and the Nereid, we have, in like manner, an
embodiment of powers which the poet-philosopher saw in his visions
presiding over the mountain, the forest, and the ocean. Content with
these, invested as they were with poetic beauty, man for ages held
them most religiously sacred; but the progress of natural science
has destroyed this class of creations. “Great Pan is dead,” but the
mountains are not voiceless; they speak in a more convincing tone; and,
instead of the ear catching the dying echo of an obscure truth, it is
gladdened with the full, clear note of nature in the sweetest voice
proclaiming secrets which were unknown to the dreams of superstition.
FOOTNOTES:
[261] _Reports of the Fauna of the Ægean_: by Professor
Forbes.--Reports of the British Association. _On the Physical
Conditions affecting the Distribution of Life in the Sea and the
Atmosphere, &c._: by Dr. Williams. Swansea.
[262] _The Vestiges of the Natural History of Creation._
[263] _General Outline of the Animal Kingdom_: by Professor Thomas
Rymer Jones, F.Z.S.
[264] In addition to the memoirs already referred to, Note p. 211,
see Carlisle, _On the battery of the Torpedo, governed by a voluntary
muscle_.--Phil. Trans., vol. xcv. p. 11. Todd, _Experiments on the
Torpedo of the Cape of Good Hope_.--Ibid., vol. cvi. p. 120. Todd,
_Experiments on the Torpedo Electricus at La Rochelle_.--Ibid., vol.
cvii. p. 32.
[265] For a concise account of these experiments see _Elements of
Natural Philosophy_: by Golding Bird, A.M., M.D., &c. 3rd Edition,
chap, xx p. 336. In this work all the most recent researches are given,
and the authorities referred to; see also Matteucci’s interesting
papers already quoted.
[266] _On the laws according to which the mixing of fluids, and their
penetration into permeable substances, occurs, with special reference
to the processes in the Human and Animal Organism_, by Julius Vogel, of
Giessen: translated for the Cavendish Society. Liebig, _On the Motion
of the Juices in the Animal Body_.
[267] _A General Outline of the Animal Kingdom_: by Thomas Rymer Jones,
p. 54, et seq.