Chapter THE TENTH (2)

We may add that the analogy between the modes of reproduction, in the two kingdoms, animal and vegetable, does not limit itself to these conditions of likeness; we may observe resemblances in the specialities of the function. Particular vitality, a turgid state of the tissues, accompanied by elevation of the local temperature, occur in the case of certain plants at the moment of impregnation, especially in the species of the family of Aroïdes. On placing a thermometer, at that time, in the great floral covering of the Arums, an excess of from 1° to 2° on the temperature of the surrounding air will be denoted, an extraordinary fact in vegetable life, for vegetables are always colder than the external air. How can we believe that the plant in which this excitement takes place has no feeling of its own condition? The plant, like the animal, has its seasons of love, can it be that it has no consciousness of them? Are we to believe that the plant which becomes warm, in which life rises at the moment of impregnation, has no more sensation than a stone? Such is not our opinion. We cannot understand life without sensibility--the one appears to us to be the indication of the other.

The analogy between the plant and the animal in their functions of reproduction is nowhere more evident or more curious than in a vegetable production which abounds in the waters of the Rhône, and has received the name of _Vallisneria spiralis_. In this plant the male and female organs are placed on different branches of the same plant. The female flowers are fixed to the ground by long, twisted, spiral stalks. But, when seeding time comes, the spirals of the stems unroll themselves, and the female flowers come up to the surface of the water and spread themselves out. The male flowers, not being placed like the female on elastic stems, cannot come up to the surface of the water. What do they do? They burst through their covering, and float around their females on the surface of the water. After that the current carries away the detached male flowers; and the female stem folds itself up again, and sinks to the bottom of the river, there to ripen its impregnated ovules.

The function of reproduction in plants is rich in conclusions in support of our thesis. The plants called phanerogamous are not reproduced only by impregnation by means of the visible sexual organs, the pistil and the stamen, they are also multiplied by grafts, buds, and cuttings. Cryptogamous plants, which have no sexual organs, are multiplied either by effects which detach themselves from the individual plant at a certain period of its vegetation as we see in the case of fungi, algæ, mushrooms, &c., or by fragments of the individual itself, which, being thrown into the ground, germinate and multiply themselves.

Animals, in their several classes, represent all these modes of reproduction; there is not one which does not exist among them. Animals are not reproduced by eggs only, either interior or exterior, and by living young ones, they are equally multiplied, like vegetables, by offsets, by cuttings, and by ingraftment.

Multiplication by offsets may be observed in the fresh-water polype. Little buds which grow and lengthen come out of the body of this animal. While the bud is lengthening, he throws off other and smaller offsets, which throw off still smaller ones. All these are so many little polypes, which derive their nourishment from the principal polype. Having attained a certain size, these offsets separate themselves from the primitive individual, and constitute so many new polypes. Coral multiplies itself in the same manner. From the principal branch spring secondary branches which have originated in a bud or shoot, and these branches, inserting themselves into the chief stem, form new individuals. Thus the exterior aspect of the coral resembles a ramified tree rather than an animal.

Madrepores, another kind of zoophytes, resemble trees so closely, that for centuries they were supposed to be marine plants; they too, like coral, are reproduced by offsets.

Multiplication by cuttings is seen in the fresh-water polype. Take a fresh-water polype, and cut it into as many fragments as you choose. Each of these fragments, left to itself, will become a polype. These new individuals may be in their turn cut into pieces, which will produce as many new ones. This is multiplication by cuttings, exactly similar to the process in plants, so that the generation of fresh-water polypes does not differ from that of one of our fruit-trees. It is not only the entire polype which, thus cut to fragments, furnishes a new polype; the skin of this animal can also produce one new individual or several. Is not this a vegetable ingraftment?

A similar generation by ingraftment is to be observed in another instance, in the case of the fresh-water polype. Take different portions of the same polype, or those of different polypes, and join them at the ends, or lay them upon one another, and you will combine them so closely that they reciprocally nourish each other, and ultimately form only one individual. Here is vegetable ingraftment carried out in an animal.

5. Other points of resemblance exist between plants and animals. If they are not generally remarked, it is because the authors of the classics of natural history do not direct the attention of the reader to these facts. We are about to supplement their silence, and to bring the analogies between the two natural kingdoms into view.

Firstly, there exists in both a common and equally astonishing fecundity. Among plants, as among animals, one individual can give birth to thousands of individuals like himself. Vegetables are even more fertile than the superior animals. Trees produce every year, and sometimes for a century. Mammiferous animals, birds, and reptiles produce infinitely less than trees; their pregnancy is less frequent, and takes place during a certain period in the life of the animal only. The elm produces every year more than 300,000 seeds, and this may continue for a hundred years. Fish and insects approach most nearly to trees in fecundity. A tench spawns 10,000 eggs yearly, a carp 20,000. Among insects, a female bee produces from 40,000 to 50,000 eggs. To these animals we may compare, among vegetables, the poppy, the fern, the mustard plant, which produce incalculable quantities of seeds. We must not forget, besides, that vegetables multiply themselves in many ways, whereas each animal possesses but one mode of reproduction.

What we wish to establish, what is evident, is that among both animals and plants fecundity is equal, and equally prodigious. From the point of view of this analogy, we may also quote the size of the species, which is extremely variable in both kingdoms, because both produce at the same time giant species and dwarf species. Among animals, there are some of monstrous size, such as the whale, the cachalot, and the elephant, such as the gigantic reptiles of the ancient world, the ichthyosaurus, which was longer than the whale, the megalosaurus and the iguanadon, which were as large as the elephant.

To these colossi of the animal kingdom, we may oppose the colossi of the vegetable kingdom; the monstrous baobab gourd, which covers hundreds of square yards with its shade, the elm, whose trunk may grow to the size of a whale's girth, the _Eucalyptus globulus_, an Australian tree which is being acclimatized in Algeria and in the south of France, the _Sequioœa gigantea_, the giant of Californian forests.

If the two kingdoms of nature have their colossi, they have also their dwarfs, and their infinitely little. There are cryptogamic vegetables which are only to be seen with the microscope, and there are animalculæ equally invisible to the naked eye. If the animal kingdom can show, in its scale of size, the whale, and the microscopic _acarus_, the vegetable kingdom possesses a similar decreasing scale from the baobab to the lichens.

The same places are inhabited or resorted to by plants and animals. Both live on the same soil, as if for mutual aid. The two kingdoms combine at all points of the globe. We might name a number of places in which certain plants and certain animals thrive together. The chamois and the maple tree love the same mountains, the same high places; the truffle and the earth-worm dwell in the same underground region; the birch and the hare are found in the same place; the water-lily grows in the same fresh water with the aquatic worm; and the cod and the algæ prosper in the same submarine depths.

All vegetables and animals have an original country, but they can be acclimatized under other skies by human industry and skill. The chestnut-tree and the Indian cock, the peach-tree and the turkey, transported to Europe, has each forgotten its native land.

Among both animals and plants there are amphibious creatures. The frog, and the other batrachians, live, like the reeds, on the earth and in the water. Both animals and plants can live as parasites. The animal world has the flea, the louse, the acarus; the vegetable world has its lichens, and its mushrooms.

Thus, equal fecundity, similar variety in the scale of size, analogy in habitation, which implies ideality of organization, possibility of transplantation and of acclimatization out of their original country, possibility of amphibious existence, parasitical life, all general conditions which suppose a great analogy of organization; we establish all these things in drawing the parallel between plants and animals. How, then, if we grant sensibility to one of these kingdoms, can we deny it to the other?

6. Plants, like animals, have their maladies. We do not now allude to maladies caused by parasites, like the sickness of the vine, due to the _oïdium Tuckeri_, the sickness of the petals, caused by other small mushrooms, that of the rose-tree, the olive-tree, of corn, &c., produced by parasitical cryptogams, which fix themselves on the plant, and change the normal course of its life; we speak of morbid affections, properly so called. The pathological condition and its consequences exist in the plant as in the animal. Stoppage, or febrile and abnormal acceleration of the sap in the vegetable, answer to stagnation of the blood, or its acceleration during fever, in the animal; various excrescences of the bark, analogous to affections of the skin; the abortion of certain organs, and the capricious development of others; the secretion of pathological liquids which flow outside. This is a brief catalogue of the maladies to which trees, shrubs, and herbaceous vegetables are subject. A plant which passes too quickly and too often from intense cold to extreme heat, soon becomes ill, and necessarily perishes, like an animal exposed to those dangerous alterations. A shrub left in a current of cold air could no more live than an animal if kept in a similar place. In a word, the plant exhibits health or sickness, according to its conditions of existence. How can we admit that the being in which such changes take place, can be merely the passive subject of them, that it experiences neither pain nor pleasure in passing from health to sickness, or from sickness to health?

7. Sicknesses, or other causes, produce anomalies of form, or irregularities of structure in plants, as in animals. Just as in the animal kingdom _monstrosities_ exist, there are monstrosities in the vegetable kingdom. The science which occupies itself with monstrosities in animals is called _teratology_. Geoffrey St. Hilaire has made some most interesting studies of the causes of the productions of monsters in the different classes of animals; but it has been perceived of late that an analogous science must be created, for the explanation of monstrosities proper to the vegetable kingdom, and Moquin Tandon has published a book upon _vegetable teratology_.

8. Old age and death are common to both plants and animals. Plants, after having survived the various maladies which threaten them, do not escape a slow old age, and death necessarily follows. With time, their vessels become hardened, their size becomes reduced, they can no longer give passage to the sap, or other liquids which ought to go through them. Liquids are not aspired with the same regularity, they no longer transude through the vegetable tissue with the same precision; they remain stagnant in the vessels, become corrupt there, and transfer their decomposition to the vessels which enclose them. Thenceforth the vital functions cease to be performed, and the plant dies. Things happen in a like manner among animals. The thickening of the vessels, the decrease of their power bring on the condition of old age, in which the functions are disturbed and slackened; then comes death, the inevitable end of all, in each kingdom of nature.

Thus, when we compare animals and plants, and especially when we consider the inferior beings in both kingdoms, it is impossible to establish a precise line of demarcation between them. The characteristics by which the old naturalists defined the distinction between plants and animals, are now acknowledged to be without meaning, and this distinction becomes more and more difficult in proportion as we make progress in our knowledge of these creatures. Voluntary motion was regarded as the principal distinctive characteristic between the two kingdoms of nature; but at the present day this characteristic can no longer be invoked. Elementary works on botany now tell us about the fly-catching plant, which catches the insect that crawls over its leaves, exactly as a spider catches flies, and about the oscillating plant, whose leaves are endowed by voluntary motion, more distinct than that belonging to many animals.

Apart from these examples, drawn from classical works, we would ask what becomes of the argument for the immobility of plants, considered as a distinctive characteristic of the vegetable kingdom, when we see that zoophytes are fixed to the earth, and when, on the other hand, we see certain young plants, or their germs, such as the germs of algæ, mosses, and ferns, possessing the faculty of motion.

The _spores_, or reproductive organs of algæ, and the _impregnating corpuscles_ of the mosses and ferns, possess the fundamental characteristics of animality, that is to say, they are provided with locomotive organs, and they execute movements which appear to be voluntary. Those singular creatures are seen to go and come in the interior of liquids, to endeavour to penetrate into cavities, to withdraw, return, and definitively introduce themselves with an apparent effort.

The German botanists regard these vegetable germs as belonging to the animal kingdom. Considering that only animals have the organs of motion, and that the spores of algæ and the impregnating corpuscles of mosses and ferns are provided with organs of motion, they do not hesitate to declare that in the commencement of their life, algæ, mosses, and ferns are in truth animals, which become plants when they fix themselves, and begin to germinate. French botanists have not yet ventured to adopt that view; they are content to call the movable impregnating corpuscles of algæ, mosses, and ferns, _antherozoïdes_, but they do not dare to pronounce upon their animality. M. Pouchet says, in his work _L'Univers_, page 444:

"Motion manifests itself spontaneously with extraordinary intensity
in the _animalculæ_ of several plants, which have spinal organs for
this purpose, hairs by means of which they swim about in the liquid
which contains them.

"Some of these, real animalcule plants, have the shape of eels, and
move themselves by means of two long filaments attached to their
heads; others exactly resemble the tadpoles of frogs, and jump
about in the cells of the mosses.

"Nevertheless, it is such creatures as these, whose locomotive
organs are so plainly to be discerned, and which we can see,
under the microscope, jumping about as nimbly as our acrobats,
that certain botanists persist in considering, on theory alone,
as motionless and insensible. Some philosophers certainly possess
eyes, that they may not see!"

There are these germs of plants, and young plants which move, and on the other hand, almost all the adult zoophytes, sponges, corals, madrepores, sea-stars, byssus, &c., &c., to which we may add several mollusca (all those in shells), are fixed to the earth. In these cases we must take the plant for the animal, and the animal for the plant, if we positively hold by voluntary motion as an absolute distinction between animals and plants.

On the borders of the two kingdoms,--when we consider zoophytes in the animal, and cryptogams in the vegetable kingdom,--there is no longer, so to speak, either animal or plant; the two seem to be confounded, and fused together.

If, before the discovery of the fresh-water polype, that living creature had been presented to a naturalist, he would have felt puzzled how to class it. Seeing it multiplying itself by buds, by offshoots, by engraftment, he would doubtless have declared that this organized being was a plant. But if he had been made to remark that this same creature fed on living prey, which it seized and swallowed, that it had long and flexible arms, of which it formed a kind of net for the purpose of seizing this prey, which it conveyed into the interior of a digestive tube, our naturalist would have made haste to place the polype in the ranks of the animals. He would have been asked to observe that the polype may be turned inside out, like a glove, so that his interior skin becomes his exterior skin, and that, thus turned inside out, he lives, grows, and multiplies himself, precisely as he does before this curious reversal. Our naturalist, much embarrassed in the presence of so unheard of a fact, would doubtless immediately have begun to seek some intermediate kingdom between the animal and the vegetable, to which he might relegate this paradoxical being, which could not, with absolute certainty, be classed either with plants, or with animals.

The fact is, classifications are products of human science, nature knows nothing about them. We descend, by insensible degrees, from one kingdom to the other; we go from the man to the polype, and from the polype to the rose tree, by infinite gradations, and, on the confines of the two kingdoms, there is a whole series of creatures which it is very difficult to range under any system. For how long did naturalists hesitate before they regarded infusoria, coral, sponges, star-fish, gorgons, sea-anemones, and madrepores as animals? Even in the present day micrographers who study the microscopic beings proper to vegetable and animal infusions, such as the monads, polypoid worms, and numerous others, find the utmost difficulty in assigning these creatures to such or such a kingdom, and they sometimes decide rather arbitrarily upon placing them among animals or plants.

From all the considerations, all the facts which we have just advanced, we conclude that the sensibility of plants is not to be contested, since no one can think of denying that privilege to certain zoophytes which can with difficulty be distinguished from vegetables.

We see an imposing tree, a stately oak with sturdy branches, growing on the sea coast. Not far off, on the sand of the shore, lies a star-fish flung there by the waves. A few yards below, on the surface of the water, floats a sponge, a branch of coral, a madrepore. When the icy wind blows, when the hurricane lifts the angry waves, which is it, the animal or the plant that will manifest sensibility to the tempest? The sponge, the coral, the madrepore will remain as indifferent to the fury of the elements as the rock in which they are incrusted, or as the pebble on which the star-fish stretches out its four motionless arms. But, the majestic oak will shudder at every gust of the tempest; he will bend his branches and shut up his leaves to shelter himself from the icy blast or the furious storm; and a mere glance at his attitude will indicate to you that an abnormal perturbation reigns in the atmosphere. Would you seriously say, in that case, that the vegetable feels nothing, and that the animal is sensible? Would you not, on the contrary, be inclined to declare that the tree is the sentient being, and that the star-fish, the sponge, the madrepore, are the creatures which are destitute of feeling?

Pause beside still water and seek for the polype or fresh-water hydra which we have just mentioned. You will find it difficult to disentangle this zoophyte from the reeds and willows which surround it. You will find, at length, a kind of membranous tube, a few centimetres in length. Is that the polype you were looking for? Is it not rather the stubble of some reed or grass plant? This living twig, with nothing to distinguish it in appearance from a herbaceous plant, is constantly fixed in the same place, like an aquatic vegetable. It makes some faint movements, consisting simply of the opening and shutting of the orifice of the tube, which solely constitutes its being. Sometimes it lengthens, sometimes it contracts itself, by stretching out membranous arms, as fine as threads, by means of which it seizes and drags towards it the water insects which chance to pass near it. This is the one single characteristic of its animality. At this rate, an aërial plant, the _fly-catcher_, would be just as much an animal as our polype, since it catches the insects which venture to crawl upon its leaves.

At the bottom of the sea there is a very curious zoophyte, the _actinium_, or sea-anemone. For a long time this creature was confounded with the plants, and held to be an ocean flower. Those who admire the beautiful, bright-coloured actinia, in the Garden of Acclimatization, in Paris, who look at them, waving on their flexible stem, shaking the coloured appendages and fringes which adorn their heads, find it hard to regard these charming queens of the waters otherwise than as real flowers. And, in fact, for ages, the _sea-anemones_ were held to be marine plants.

In the last century, coral was held to be a marine shrub, and it was even believed that the flowers of the coral had been discovered. An academician of Paris, Count de Marsigli, created a European reputation for himself by this supposed discovery. Peyssonnel, a Provençal naturalist, found the utmost difficulty in opposing this idea, and in establishing the fact that these supposed flowers of the coral were in reality young corals. He had the whole Academy of Sciences against him; and his opposition to the ideas of the Academy brought him into such disgrace, that he was obliged to leave France and to go to the Antilles, where he died in obscurity as a doctor of medicine. And all this because he maintained that coral is not a plant, and does not produce flowers!

The famous Genevese naturalist, Charles Bonnet, anticipating the knowledge of our day by more than a century, has given a most interesting form to the parallel between animals and plants, in his work entitled _Contemplation de la Nature_. We cannot resist the pleasure of quoting the following passage, in which Charles Bonnet shows in a striking manner what are the difficulties in the way of distinguishing the plant from the animal, and how those difficulties are disposed of by those who dispute the sensibility of plants:--

"Everything is graduated in nature," says Charles Bonnet, "and, in
refusing to admit that plants are sentient, we force nature to make
a jump without any assignable reason.

"We observe that feeling decreases by degrees from man to the
nettle, and to the mussel, and we persuade ourselves that it stops
there, because we regard these animals as the least perfect. But
there are, perhaps, many degrees between the feeling of the mole
and of the plant. There are, perhaps, still more between the most
and the least sensible of the plants. The gradations, which we
observe, ought to persuade us to this philosophy; the new beauty
which it adds to the system of the world, and the pleasure to be
derived from the multiplication of sentient creatures ought to
contribute to induce us to admit it. I willingly admit that this
philosophy is much to my taste. I love to think that those flowers
which adorn our fields and our gardens with a brightness constantly
renewed, those fruit trees which are so pleasant to our eyes and
our palate; those majestic trees that compose the vast forests,
which time seems to have respected, are so many sentient creatures
partaking after their fashion in the sweetness of existence.

"Plants offer some facts to our observation which seem to indicate
that they possess feeling, but we are not likely to perceive those
facts, because of the strong persuasion that they are insensible,
which has prevailed among us for so long. We ought to agree to
consider the question _tabula rasa_, and to subject plants to
a new, impartial, and unprejudiced examination. An inhabitant
of the moon, possessed of intellectual faculties like ours, but
without any preconceived ideas about the insensibility of plants,
would be the philosopher whom we require. Let us imagine such
an observer engaged in studying the productions of our earth,
and, after having given his attention to the polypes and other
insects multiplied by the process of grafting, passing on to the
contemplation of vegetables. He would, doubtless, take them at
the period of their birth. With this view, he would sow seed of
various species, and he would carefully watch their germination.
Let us suppose that some of those seeds have been reversed in the
sowing, the sprouting part turned downwards, the stem upwards; and
the observer has the skill to distinguish one end of the seed from
the other, and knows their functions. After some days, he will
remark that the seed has grown into this reversed position, that
the stem is turned upward, and the sprouting portion downward. He
will feel no surprise; he will attribute a circumstance which is
so hurtful to the life of the plant, to the mistake he has made in
sowing the seed. But, continuing to observe, he will see the sprout
and the stem each bending itself in the opposite direction, and
trying to attain the right position. This change of direction will
strike him as very remarkable, and he will begin to suspect that
the organized being which he is studying is endowed with a certain
amount of discernment. Too prudent, however, to pronounce upon
these early indications, he will suspend his judgment and pursue
his investigations. The plants whose germination our physicist
has been observing, have been raised in the neighbourhood of a
hedge. Thus favoured, and carefully cultivated, they have made
great progress in a very short time. The soil which surrounds them
at some distance is of two opposite qualities. That on the right
of the plants is rich, damp, and spongy; that on the left is dry,
hard, and gravelly. Our observer remarks that the roots, after
having begun by extending equally on both sides, have changed their
direction, and have spread out towards the rich and humid soil;
over which they are stretching, and thus threatening to deprive
the plants already there of their due share of nourishment. To
prevent this inconvenience, he digs a ditch between the plants
which he is observing and those they threaten to starve, and now he
thinks he has provided against everything. But the plants, which
he believes he has governed, disconcert all his precautions by
extending their roots downwards, under the ditch, and gaining the
other side.

"Surprised at this, he uncovers one of these roots, but without
exposing it to heat, and holds a sponge steeped in water towards
it. The root turns itself to the sponge, and when he changes its
position, the root accommodates itself to each alteration.

"While our philosopher is meditating profoundly upon these
facts, other facts equally remarkable present themselves almost
simultaneously. He observes that all these plants have leaned away
from the hedge, and are bending forward as though to present every
portion of their bodies to the beneficent smiles of the sun. He
sees that all the leaves are so turned that their upper surface is
exposed to the sun, or to the fresh air, and that the lower surface
is directed towards the hedge, or the ground. Former experience
will have taught him that the upper surface of leaves serves
chiefly as a defence for the lower surface, and that the latter
is principally destined to pump up the moisture rising from the
earth, and provide for the evacuation of what is superfluous. The
direction of the leaves which he notices appears quite in harmony
with his experiences. He studies this portion of the plant with
increased attention.

"He remarks that the leaves of some species seem to follow the
movements of the sun, so that in the morning they turn to the
east, in the evening to the west. He sees that some leaves close
themselves against the sun, others against the dew. He observes an
analogous movement in certain flowers. Afterwards, he observes
that no matter what the direction of the plants relative to the
horizon has been, the direction of the leaves is always that
which he has at first noticed, he bethinks him of changing this
direction, and of placing the leaves in a position exactly contrary
to their natural one. He has already had recourse to similar
means in order to assure himself of the instinct of animals, and
to ascertain its bearings. With this view he bends perpendicular
plants towards the horizon, and keeps them in that position. Thus,
the direction of the leaves is absolutely changed; the upper
surface, which previously turned to the sun or to the fresh air,
now looks towards the earth or the interior of the plant, and the
lower surface, which formerly looked towards the earth or the
interior of the plant, now turns to the sun, or the fresh air. But
very soon all these leaves begin to move, they turn on their stem
as on a pivot, and in an hour they will have resumed their former
position. Our observer, wishing to assure himself whether leaves
and branches when detached and plunged into water will preserve
the inclinations which they manifest when upon the plant of which
they formed a portion, subjects them to an experiment whose results
leave him no doubt of the fact.

"He places wet sponges under the leaves, and he sees the leaves
turn towards the sponges and endeavour to adhere to them by their
lower surfaces. He also observes that certain plants, which he has
shut up in his cabinet and in a cellar, have turned towards the
window, or the grating respectively.

"Finally, the phenomena of the Sensitive Plant, its varied
movements, the promptitude with which it contracts when touched,
form the interesting subject which terminates his researches.

"Thus plentifully supplied with facts which all seem to tend to the
support of belief in the sensibility of plants, which side will
our philosopher take? Will he surrender to these proofs? Will he
suspend his judgment? I think he will take the first part."[16]

Charles Bonnet believes, in short, that the plant, as well as the animal, is endowed with sensibility.

According to the system which we have developed, the animal is possessed of a soul, which is still very imperfect, and endowed only with faculties corresponding to its needs. But, since the animal, in addition to the sensibility enjoyed by the plant, possesses intelligence also, we must conclude from thence that the plant has not a soul, properly so called, but only the rudiment, the commencement, in other words, the _germ_ of a soul.

We know that the sun has the privilege of giving birth to organic life upon our globe, his rays have power to produce the formation of living tissues, plants or zoophytes, when they fall upon the earth or the waters, and we may draw this conclusion from all that has gone before, that the sun sends down upon the earth _animated germs_ under the form of his rays, which emanate from the spiritualized creatures who dwell in the king-star.

Thus our system of nature completes itself; thus, thanks to solar radiation, the two ends of the immense chain of organized beings whose place and part in the vast theatre of the worlds we have attempted to define are united. Life begins in the waters, its first appearance is in plants and zoophytes; for these two classes of living creatures obey the same laws, and appear to have the same origin. The sun, by sending his vivifying rays upon the earth, produces the formation of plants and zoophytes, which are the points of departure of organization. The _animated germ_ deposited by the sun in plants and zoophytes grows, passes from the zoophyte to the mollusc, or articulated animal, and then undergoes a further development, by passing from the mollusc or articulated animal to the fish. This germ of a soul thus becomes a rudimentary soul, provided with certain faculties. In the zoophyte and the mollusc it had only sensibility; in the fish, and then in the reptile, and the bird, it has attention and judgment. The faculties are augmented in proportion as the animal mounts higher in the organic scale. Arrived at its summit, the human being, the soul is in possession of all its faculties, and especially of memory, which during the animal stages of the ascent is obscure and uncertain.

To accord sensibility to plants permits us to unite all the creatures of the living creation, and thus to complete our general system of terrestrial nature.

FOOTNOTES:

[15] "_Histoire des Plantes_," Paris, p. 111.

[16] "_Contemplation de la Nature_ (_Œuvres d'Histoire Naturelle de Charles Bonnet._") Neuchâtel, 1781.

CHAPTER THE THIRTEENTH.

DOES MAN EXIST ELSEWHERE THAN ON THE EARTH?--DESCRIPTION OF THE PLANETS.--PLURALITY OF INHABITED WORLDS.

THROUGHOUT the preceding chapters we have reasoned as if the earth were the whole universe. Indeed, almost all men believed that such was the case, from the first establishment of society until the last century. Great mathematical knowledge, profound study, and highly perfected optical instruments are requisite to rectify the false ideas, the errors, and the illusions which are the result of a simple view of the earth and the sky. Great efforts of the mind, and a very difficult struggle against the testimony of our senses are necessary to the recognition that the earth moves, and that the sun is motionless. In order to distinguish the place and the office of each of those softly beaming globes, in the midst of the uniformity of aspect presented by the stars which shine during the night, patient and severe observations, transmitted and repeated from age are indispensable, and, in addition, an excellent scientific method. Let us therefore not be surprised that men have taken so much time to comprehend the ordering of the universe, and that they had only the most childish conception of them for thousands of years. The ancients, the Greeks, the Romans, the Egyptians, knew nothing of the universe, except the earth (nor did the Orientals, with the exception of some truly learned men, who had divined the general mechanism of the universe by methods unknown to us, but they concealed their knowledge from the profane). These ancients could speak of only a small portion of the globe: of Europe, Asia, and the North of Africa. The remainder was a dead letter for the peoples of antiquity. After them, and following their example, the first Christians reduced the universe to what they knew of it; they believed there was but one world, because they saw only one. The earth was for them the universe. In the stars they saw only brilliant spots, like silver nails in the celestial vault, to enhance the azure, and charm the eyes of men in the quiet of the night. The moon was the natural beacon of the earth. In the sky there was a shining track followed by the sun, and the torch of day was no larger than the beacon of night. The celestial region which spread itself above the sun and the moon was the Empyrean of the ancients, the Paradise of the Christians and the Mussulmans. It was at once the sojourn of clouds and of light, the habitation of the elect of God, of the saints and the just. Under the earth, and in its interior, were immense abysses, gulfs, and cavities, the dark dwellings of the damned.

This simple cosmogony, which merely translates what our eyes show us, has been that believed by every people in their infancy. Among the savage tribes of the two worlds, in America and in Africa, as in the ancient East, among the Romans as among the Egyptians and the ancient Greeks, this coarse simplicity and absolute ignorance of the constitution of the world prevailed. On this profoundly false basis all the ancient religions were founded. The social customs of modern peoples are based upon the same errors. Language has consecrated them; the earth is everywhere called the _world_, as the ancients called it (_mundus_, κόσμος); every one says the sun _travels_, or _goes_, from east to west, and that the stars _rise_ and _set_.

Poetry has set its eternal seal on this vicious system, and has, so to speak, consecrated it, by clothing it with all the _prestige_ of genius and imagination.

Modern astronomy has caused the false skies of antiquity to vanish away; it has dispersed the pretensions of the celestial vault, sown with brilliant spots, and substituted a simple mass of coloured air. It has revealed the true office of each of those stars which we see by day or by night. It has fixed, in an indisputable manner, the real place of the earth in the universe, and, to say the truth, that place is singularly small.

We know now, that the earth, far from being herself the world, is only an imperceptible point of the world. If we only compare it with the sun, we know that our globe is one million three hundred thousand times smaller than the sun. This takes us far away from the idea of the ancient Greeks, who thought they ventured much in asserting that the sun was as big as the Peloponnesus.

In addition, the earth has been dispossessed of all privileges. It was believed formerly to be unique and unrivalled, we now know that there are an infinity of other globes similar to the earth, so that she is no more than one individual in a group of other individuals who resemble her. We know that the earth figures among the planets, that she is only a planet of our system.

What, then, is a planet? the reader will ask. An attentive gaze directed to the stars of night will make him understand it. Let him examine, on any fine evening, the star which is pointed out to him as Mars or Jupiter, and to which a certain position is assigned at a given hour. Then, a few hours later, let him come and look once more for Mars or Jupiter, and he will perceive that the position of Mars or Jupiter, with respect to the other stars, is changed. Or he may do better still. Let him look at Mars or Jupiter through the telescope of an observatory, or the glass of one of those open-air astronomers who are to be found in the public ways in Paris and other great cities. Thus he may see Mars or Jupiter change his place under his own eyes. While the other stars remain motionless, Jupiter or Mars will pass away from the field of the glass.

There are, then, fixed stars and movable stars. The movable stars are the planets (πλανήτης, from πλάνος, wandering). The fixed stars are what we _call_ stars. It is not difficult to distinguish the planets from the stars with the naked eye. The stars emit sparkling light, whence comes their name, from the Latin _stellare_, to shine, and their light twinkles. The planets, on the contrary, shine with a steady, mild, unvacillating light. The reason of this difference is, that the light shed by the stars is their own. The stars are so many suns resembling ours. They illumine worlds like our world, so prodigiously distant that we cannot even perceive them. The planets do not shine of themselves; they merely reflect, like gigantic mirrors, the light of the sun which illumines them, and renders them visible to us. Thus, the planets are stars which travel. They revolve around the sun. The earth, being a planet, is a travelling star, which revolves around the sun.

But the earth is not the only planet of our solar system. There are seven others, which do not differ essentially from the earth. The names of the eight planets which compose our solar system, are as follows, arranged according to their distance from the sun: Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Between Mars and Jupiter there is a collection of small bodies, which seem to be fragments of broken planets; they are called asteroïds. At present, in 1871, more than a hundred are known, and it is not yet fifty years since they were first sought for in the sky. These asteroïds may be collected together in our fancy, and formed into a separate group, which would be a ninth planet. Let us glance at the planets which compose our solar system.

Plates 4 and 5, which accompany these pages, will suffice to give an idea of the relative dimensions of the planets. In these two plates the planets are arranged according to the order of their distance from the sun. In plate 4, Mercury, Venus, the Earth, and Mars are represented; in plate 5, the asteroïds Jupiter, Saturn, Uranus, and Neptune. Mercury is the nearest planet to the sun, his distance from the central orb being only fourteen millions of leagues, which, in astronomy, is near neighbourhood. This planet revolves upon its axis with the same rapidity as the earth. The day, in Mercury, is only three minutes longer than ours (24h. 3ms.). Being closer to the sun than the earth is, Mercury turns more quickly round the sun, so that its year is only 88 days, whereas ours is 365 days.

We know that the sole cause of the inequality of the seasons, as well as of day and night in the planets, is the inclination of the star on its axis of rotation. If the planets, while revolving round the sun, retained the verticality of the axis which joins these north and south poles, there would be perfect equality in the distribution of the solar light and heat over the same latitudes; along each parallel there would be a complete regularity in the lighting and warming of the planet; the differences of heat and cold would not depend on anything but their greater or less distance from the sun. But this verticality only exists for two or three planets of our system. The others, and among them Mercury, Venus, the Earth, and Mars, are strongly inclined on their axis of rotation.

They revolve in a bent position, as if they had received a great blow on the shoulder, which had caused them to deviate from their primitive and regular situation. From this there results a very variable disposition of the duration of the light, and consequently of the heat, which these inclined planets receive from the horizontal rays of the solar star. Thus the inequality in the length of the days and nights, and the diversity of the four seasons on the same parallel, are accounted for.[17]

Mercury. Venus. Earth. Mars. Sun.

Fig. 4.--Comparative Size of the Planets Mercury, Venus, the Earth, and Mars.]

The inclination of the axis of the terrestrial sphere is 23° which is a considerable deviation, and occasions great differences in the duration of days and of seasons on different points of our globe. The inclination of the axis of the planet Mercury is enormous: it is 70°. This planet bends over itself as if about to fall. Hence results prodigious variation of light and heat on the same parallel, and seasons whose abrupt changes must be painful and hard to bear by the inhabitants of this planet, if such inhabitants exist.

Mercury is five times less than the Earth, as is shown in plate 4. Venus comes after Mercury, according to distance from the Sun.

Venus, which is 27,000,000 of leagues from the Sun, receives twice as much light and heat as our globe. Its days are of nearly the same length as ours (23 hours, 21 minutes), but its year, necessarily shorter than that of the Earth, since it is nearer to the Sun, lasts only 224 days. Its seasons last two months each. Its globe is nearly of the same bulk as that of the Earth. Venus is almost always wrapped in clouds, which must fall in rain, forming rivers and seas. These waters refresh the plains, which must be scorched by the heat of the burning sun. The seasons are still shorter and more unequal in Venus than in Mercury; its axis is, in fact, inclined at 75°.

After Venus comes the Earth, which is almost of the same bulk, but 28,000,000 of leagues from the Sun. Its diameter is nearly 3000 leagues. It accomplishes its revolution on its axis in 24 hours (23 hours, 56 minutes, 4 seconds), and in 365 days, 5 hours its revolution around the sun.

The inclination of the Earth's axis is 23°, which produces the differences of days and nights, and the inequality of the seasons, according to latitude. The Earth possesses a privilege denied to the planets Mercury, Venus, and Mars; she has a secondary star, or satellite, called the Moon. Placed at a distance of only 90,000 leagues from the Earth, the Moon accomplishes her revolution around it in 27 days. It is not the object of this work to give any description of our globe. We will suppose our readers to be sufficiently acquainted with it, and pass on to the planet which comes next to it in the scale of distance from the Sun. This is the planet Mars.

An extraordinary resemblance exists between Mars and the Earth. Physical, geographical, and climatological conditions, days and nights, seasons, celestial perspectives, all are alike in these two planets, with the sole difference that the globe of Mars is half as small again as that of the Earth; so that, if a man were transported to Mars, he might believe himself to be, not in a strange planet, but in a little known corner of the Earth, such as Australia or Polynesia.

As we pursue our journey through the heavens, ever increasing our distance from the Sun, we shall find, after Mars, the group of the Asteroïds. We shall not linger before this cluster of small stars, which is no doubt nothing but a collection of the dismembered fragments of a planet, which formerly existed in this particular point of space, and was dashed to pieces by some formidable accident in the universe. These little stars, like the important planets, have each their names, such as _Vesta_, _Pallas_, _Circe_, &c., &c. _Maximiliana_, and _Feronia_ are placed at the two extremities, with respect to distance from the Sun. These remains of a broken star continue to circulate around the Sun, like the planet which they formerly composed.

After the Asteroïds comes great Jupiter.

Jupiter is the largest planetary sphere in our solar system, being 1400 times greater than the Earth. Its distance from the Sun is 200,000,000 miles. In consequence of this distance, its year is as long as twelve of our years. Notwithstanding its colossal dimensions, Jupiter turns with such rapidity upon its axis, that it accomplishes an entire revolution in twelve hours, so that its day and night are respectively only ten hours long. The shortness of Jupiter's nights are compensated by the existence of four moons, or satellites, which revolve around this planet, and give it permanent light. This illumination by reflection, added to very long twilights, must make Jupiter's nights nearly equal to the day in brightness.

Though Jupiter suffers under the disadvantage of very short days, it has on the other hand the inappreciable advantage of perfect equality in the length of its days and nights, and of that of the four seasons over all its parallels. The axis of Jupiter is hardly at all oblique, and therefore Jupiter, like the planet Saturn, enjoys a sort of perpetual spring, that is to say, an equable distribution of solar heat and light along the same degrees of latitude. Jupiter, unlike Mars and Venus, has no vicissitudes of seasons, no sudden and painful transitions from cold to heat in the same place. The climates are invariable in each latitude, and the seasons are hardly discernible.

The globe of Saturn is 734 times larger than that of the Earth, and is 364,000,000 leagues from the Sun. It takes thirty years to perform its revolution around the central star, and its year is therefore thirty times as long as ours.

Saturn, like Jupiter, has very short days. It revolves on its axis in ten hours, so that its day and night respectively are but five hours. But it has eight moons, or satellites, which accompany it, and give it light, thus, as in the case of Jupiter, supplementing the shortness of its days. There is hardly any obliquity of the axis of Saturn, so that its days and nights are always equal. There is a perpetual _equinox_, and the climates are invariable, while variation of seasons hardly exists. In Saturn, as in Jupiter, perpetual spring reigns. Saturn has one peculiarity which does not belong to any other body in our solar system. It is placed in the centre of a ring, of the same nature as its own, and which surrounds it on every side. This ring (see plate 5), is surrounded by a second, and the second by a third, and the whole are called the rings of Saturn. This circular envelope is exceedingly thin--only ten leagues in thickness--but very wide; its width is 12,000 leagues. It is not motionless, but it revolves with the globe which it surrounds.

The strange disposition of the rings of Saturn affords a proof of the inexhaustible riches of nature, and the variety of forms which the Creator has called into being in the vast universe. It ought to guard us against our constant tendency to model all the worlds which we do not know, upon the type of the earth.

Hardly anything is known about the peculiarities of Uranus, a planet which is only eighty-two times larger than the earth, but which is 732,000,000 of miles from the sun, and takes eighty-four years to accomplish its revolution around the central star.

Plate 5 shows the relative proportions of Uranus and the earth. The prodigious distance of Uranus from our globe, added to its small size, renders it almost inaccessible to observation.

For the same reason, nothing can be ascertained respecting the physical and geographical conditions of Neptune, the last planet of our solar system, which was discovered in our time by M. Le Verrier, thanks to the simple force of calculation, thereby affording the most brilliant proof ever given of the utility of the mathematical sciences. Neptune is so small and so far from us, that it is probable mere observation of the heavens would never have detected its existence. In this case mathematical analysis was more powerful than the telescope. It would be impossible to give particulars analogous to those which we have supplied concerning the foregoing planets, in reference to a star only 105 times larger than the earth, which revolves at the distance of _one milliard 150 millions of leagues_ from the sun, and the duration of whose year is 164 times that of the terrestrial year, so that if the ages of the Christian era were counted according to the Neptunian chronology, instead of being in the 19th century, we should be in the 12th year of that era. All we can say about Neptune, therefore, is that it forms the boundary of the domain of our visible world.

We cannot, however, state positively that our solar world terminates at this limit. No doubt the range of our astronomical glasses goes no farther, but assuredly they do not sweep the boundaries of the empire of the sun. It is known, in fact, that comets return to us after having (as indicated by their geometrical curve), swept over the depths of space to a distance of thirty-two _milliards of leagues_. Thus the distance of one milliard 150 millions of leagues, which is that of Neptune from the sun, by no means represents the confines of our solar world, but simply defines the limits of the range of our telescopes.

Fig. 5.--Size of the Planets Jupiter, Saturn, Uranus, and Neptune compared with the Earth.]

This rapid glance at our solar system in its entirety, proves that the earth is not in possession of any privilege. The part which she plays in the economy of the universe is equally fulfilled by other stars, and there is nothing to justify the pre-eminence assigned to her by the ancients. She is not the largest, the warmest, or the brightest of the planets. She simply forms a portion of a group of stars, and is but one individual of that group.