While Newton maintained that the form of the earth was that of a spheroid flattened at the poles, as a necessary sequence of the great natural law which bears his name, Jacques Cassini declared himself in favour of an elongated spheroid. The difference between these two illustrious teachers originated a controversy which lasted for upwards of fifty years. The Academy of Sciences of Paris pronounced, not unnaturally, in favour of the opinion of their colleague, though it was far from having the authority of Dominique Cassini, father of Jacques, and, still less, that of the illustrious President of the Royal Society of London. But patriotic ardour supplemented the weakness of their arguments. The flattened spheroid and Newton's law were rejected by France, because they were an English invention. Undoubtedly, no one openly acknowledged so paltry a reason, but it was certainly true as a sentiment. As everybody knows, it was Voltaire who first removed the prohibition, and popularised the Newtonian philosophy in France.

How did our astronomers finally succeed in demonstrating mathematically the veritable form of our planet?

To obtain a clear and accurate conception, we are obliged to transport ourselves back two thousand years. Let us recall, in the first place, that, owing to the diurnal movement, all the stars progress from east to west; that they rise and set, to recommence the same rotation. This is a general and conspicuous fact, which everybody can confirm for himself. But now for another, whose observation requires a little more time and patience. During the diurnal movement, which carries on all the stars and the sun himself, the latter progresses independently, in the inverse direction of the celestial vault, as a fly might do upon a revolving globe. But this second fact is complicated with a third: While advancing on his own account, from west to east, the circle which the sun traverses is not parallel to the Equator; the radiant luminary transports himself alternatively into the northern and southern hemispheres, accomplishing this rotation in 365 days and a fraction of a day, in an oblique plane, which cuts that of the Equator under an angle of about 23½°.

Let us here take advantage of a parenthesis to explain a few astronomical technicalities, necessary for the due comprehension of our subject.

It is in the plane, or oblique circle,—ὁ κῦκλος λοξός;, as Ptolemæus called it,—that eclipses occur, owing to the relative positions of the sun, earth, and moon; and it is for this reason modern astronomers have denominated it the Ecliptic. The Ecliptic is the Equator of the oblique sphere (σφαῖρα ἐγκεκλιμμένη), properly so called, as the Equator is that of the sphere of the world, or the right sphere (σφαῖρα ὀρθή). The circles parallel to the Ecliptic, which continue to diminish in diameter up to the poles of the oblique sphere, bear the name of parallels of latitude; and we give that of meridians of longitude or oblique ascensions (ἀναφοραὶ λοξαί) to the great circles which cut the first rectangularly as they all pass through the axis and the poles of the Ecliptic. The same division by circles cutting each other rectangularly has been made on the right sphere, or sphere of the world. Only, there the latitudes are named declinations, and the longitudes right ascensions. The general diurnal movement is a movement in right ascension; it is measured upon the Equator. The individual annual movement of the sun is a movement in longitude; it is measured upon the Ecliptic.

The zone, or belt, which the sun seems to trace in its annual march, from the limit of its southern excursion (the winter solstice) to the limit of its boreal excursion (the summer solstice), and in returning from that limit to the other, after having twice passed through the equinoctial line (or Equator),—this zone is marked on the firmament by a belt of constellations known as the Zodiac.

These constellations are named, according to the figurative grouping of the stars (on which we have commented in Book I.),—the Ram, the Bull, the Twins, the Crab, the Lion, the Virgin, the Balance, the Scorpion, the Archer, the Cow, the Water-bearer, the Fishes. There are twelve, three for each season. The constellations represented by these figures, so singularly chosen, spread over the whole celestial vault,—that is, over an extent of 360°.

To resume.

The heavens, like earth, have their annals: everything changes there as in the human world. In the age of Hipparchus,—or some two thousand years ago,—the sun entered, at the spring equinox, into the zodiacal sign of Aries; in the summer solstice, it entered into that of Cancer; at the autumnal equinox, into Libra; and at the winter solstice, into Capricorn. These signs then corresponded exactly to the constellations which they represent.

Now, whatever Aristotle and his disciples may say, the firmament is not incorruptible (ἀφθαρτός) and immovable; even the fixed stars, as we call them, change their place in time. We have seen that the whole celestial vault or "right sphere" runs, from east to west, around the poles of the world; we have seen also that the sun moves, on his own account, from west to east, around the poles of the oblique sphere, or the Ecliptic. Well, this does not suffice; there is a third movement to be observed,—that of the right sphere itself round the poles of the Ecliptic; and this, not like that of the sun, from west to east, but inversely, from east to west. Only, this movement of the starry sphere in longitude, or parallel to the plane of the Ecliptic, is extremely slow, compared with the movement of the same sphere in right ascension, or parallel to the Equator of the world. While the former traverses in twenty-four hours the 360° of the circle, the latter occupies (in round numbers) 25,000 years.

Who was the first discoverer of the slow movement of the heavens? Hipparchus. This great astronomer, on comparing his own observations with the more ancient ones of Aristillus and Timocharis, succeeded in ascertaining that the constellation which, 150 years before him, corresponded to the spring equinox, did not, in his time, any longer coincide exactly with the same equinoctial point, but had outstripped or preceded it about 2°. This is what we mean by the precession of the equinoxes.

Hipparchus was at first of opinion that this movement affected only the constellations of the Zodiac; but he soon became assured of its universality. He perceived that if it does not alter the parallels of latitude; because it has occurred parallel with the Ecliptic, it makes the position of the equinox retrograde from east to west, and the sun pass slowly through the same constellations in the reverse of the order in which he annually traverses them.

We know this movement now to nearly the fraction of a second. By an inappreciable daily quantity, it rises, at the end of the year, to 50".3,—in a century, to about 1½°,—in twenty centuries, to 30°, or the twelfth part of the Zodiac. It is for this reason the Ram, which, in the days of Hipparchus, was occupied by the sun in spring, has no longer any value as a commemorative sign; it gives place now-a-days to the constellation of the Fishes, and corresponds to the constellation of Taurus, or the Bull; the constellation of Taurus to Gemini, or the Twins; the constellation of the Twins to Cancer, and so on. But little more than a month, then (a month of 2000 years!), of the great year (a year of 25,000 years!) has elapsed since the epoch of Hipparchus. It is to astronomy especially that, with a slight variation, we may apply the aphorism of Hippocrates—"Brevis vita, ars longa" (Life is short, and art long).

The precession of the equinoxes explains why the pole of our starry vault does not occupy invariably the same point of the firmament, and why the constellations which we now see shining during the nights of a given season change their places as time glides by.

But what is the cause of this movement?

Before this question, as before a sovereign tribunal, appear the two opposite doctrines which have been enunciated on the value of the earth and the sun in the world's system. According to the doctrine at once the oldest and most intolerant, the earth occupies immovably the centre of the world; the sun and the planets are only its satellites; they, like the moon, revolve around the earth; finally, all the starry sphere, the whole celestial vault, rotates upon its own axis in four-and-twenty hours. We have been speaking as if this were really and truly the condition of things. If we admit this doctrine, which bears the name of the Ptolemean system,—though, in truth, it is probably as old as humanity itself,—how shall we explain the precession of the equinoxes? We cannot do otherwise than suppose, that while the celestial sphere executes its diurnal movement round the poles of the world, it executes another and much slower movement round the poles of the Ecliptic.

But this assuredly is a most singular supposition. What! the same starry sphere revolves at one and the same time parallel to the plane of the Equator, and parallel to another plane (the Ecliptic) inclined upon the first? After having imagined eight spheres of crystal to explain the movements of the moon, the sun, the planets (Mercury, Venus, Mars, Jupiter, Saturn), and the stars, do we require a ninth? Where will you stop, if you begin to discover additional movements? You are condemned to wander from hypothesis to hypothesis, until you fall into an abyss of contradictions!

Such is the language employed by the tribunal of posterity, in addressing itself to the error which would substitute appearance for reality.

According to the other theory, it is the sun which occupies the centre of the system, and it is the earth which, accompanied by the remainder of the planets, revolves around it. This theory is likewise of considerable antiquity, though generally known as the Copernican system. But four-and-twenty centuries prior to the epoch of Nicholas Copernicus, it was taught by the "Samian sage," Pythagoras, and his disciples. The system then in acceptance, however, imposed upon them the necessity of silence. Ptolemæus was acquainted with it, but endeavoured to turn it into ridicule. "There are people," he says, "who pretend that heaven is immovable, and that it is earth which revolves on its own axis; evidently these individuals are unaware how supremely absurd is their opinion (πάνμ γελοιότατον)." And it was in the name of logic and mathematics that Ptolemæus thus treated the Pythagoreans!

In the system of Copernicus,—the diurnal movement of the right sphere,—it is the earth's rotation upon its own axis which, being prolonged into the heavens, marks there, by its extremities, what are called the Poles of the world, just as the Equator of the world is simply the prolongation of the terrestrial Equator. As for the Equator of the oblique sphere (the Ecliptic), in which the sun apparently moves, it is, in reality, the identical plane in which the earth moves during its annual revolution round the sun. Now, in this movement of translation, the axis of the earth does not remain constantly parallel to itself; it deviates,—very slightly, it is true,—and so as to be scarcely perceptible to several generations of men. It is then quite natural that our successors should see, for a long time to come, the northern pole of the starry sphere near the extremity of the tail of Ursa Minor. But, two thousand years hence, this slow deviation will have become very perceptible; astronomers will then see the pole of the world in another constellation, and, as this displacement is continuous, the prolonged axis of the earth will have traced on the firmament, in 25,000 to 26,000 years, a circle parallel to the plane of the Ecliptic, and having for its centre the pole of that plane. This circle is the base of a cone whose summit rests upon the earth. (Fig. 27, a.)

But this imaginary defined circle (which appears elliptic on account of the perspective) is but the mean of a series of oscillations around the pole of the world, which changes its position, as we have just shown. (Fig. 27, b.) These oscillations originate in the circumstance that the axis of the earth inclines alternately forward and backward, in such wise, that a star, after having approached the Pole, immediately afterwards recedes from it; they cause the terrestrial globe to resemble the head of a man who, by an alternation of gesture, says alternately yes and no. Only, while man (the puppet!) occupies but a second or two in affirming and denying the same thing, the earth employs about eighteen years and a half in inclining once forward to say yes (in Latin, adnuere), and once backward to say no (in Latin, abnuere). This is scientifically denominated the nutation of the earth.

Who was the fortunate mortal to discover a phenomenon so singular? Bradley, the English astronomer; the same who discovered the aberration of light. It was in the course of his researches to determine the annual parallax or distance of the stars that, at an interval of nineteen years, he made, in 1728, the discovery of the aberration of light, and, in 1747, that of nutation.

The reader may not be displeased to know under what circumstances he accomplished the latter discovery. While observing, for several successive years, the circumpolar stars, and notably the star γ in Draco,—a constellation situated between Ursa Major and Ursa Minor (see Fig. 2, p. 9),—Bradley noticed that this star changed its position by a movement constantly directed towards the north, from 1727 to 1736, or for a period of nine years. When it had reached the latter limit, the star appeared stationary for a moment, and then retraced its course in a southerly direction. Would it also occupy a period of nine years to arrive at the limit of this contrary excursion? Bradley affirmed that it would, and communicated his prediction to a French astronomer, Le Monnier.

How was Bradley led to appear in the new character of a seer?

By two special circumstances—the universality, and the duration of the phenomenon.

If the star γ in Draco had been the only one to direct its course towards the north, Bradley would probably have been led to believe that the Pole exercised upon it a peculiar attraction; but he perceived that many other stars rose in like manner towards the Pole with an uniform and constant march; it was, therefore, more natural to suppose that the Pole advanced towards them. And what strengthened the probability of this hypothesis was, that the stars situated in the neighbourhood of the course of the solstices exhibited a corresponding displacement. But there was already recognised as in existence a peculiar movement which explained the precession of the equinoxes. Was it necessary, therefore, to suppose a second, a kind of rotatory movement? Newton had already thought of it, by imagining a nutation, through which the Pole might alternately rise and sink on the plane of the Ecliptic in the space of a year. But the displacement which occurs in that interval is too slight to be perceptible to observation. There might, therefore, be a reasonable doubt of the accuracy of Newton's idea.

Bradley resumed the idea of his illustrious compatriot. He recognised in the northward movement of the stars the effect of a similar rotation, but one which took much longer in its accomplishment. By doubling the interval of nine years, to the term of which he had seen the movement become stationary, he obtained a period nearly approaching that which the moon employs in returning to the same nodes. This coincidence flashed upon him like a ray of light.

We must here remind the reader,—who, we hope, is not weary of our scientific or semi-scientific disquisition,—that the lunar nodes,—i.e., the points of the Ecliptic through which the moon passes when it proceeds from south to north (the ascending node), and from north to south (the descending node),—are the analogues of the solar equinoxes; the equatorial points through which the sun passes on its course from south to north (the spring equinox), and in returning from north to south (the autumn equinox),—points of intersection whose retrogradation constitutes, as we have seen, the precession of the equinoxes. Well, the moon's nodes retrograde in a similar manner by a movement directed from east to west; only it is a much slower movement. While the equinoxes are displaced but fifty seconds (50") in a year, the lunar nodes, during the same period, and in the same direction, move over a space of 19° 20' 29"; so that, in less than nineteen years, they have made the complete circuit of the heavens, to return to exactly the same point, after traversing 360°.

Thus, then, we have explained the data on which Bradley rested his prediction. It was confirmed by Le Monnier, who observed, in fact, that the star γ in Draco, and the neighbouring stars, observed by Bradley from 1727 to 1736, moving from south to north, occupied the same period of time, from 1736 to 1745, in accomplishing an equal excursion in a contrary direction, from north to south. These observations enabled him to fix approximatively the quantity of the nutation.

To sum up; it was recognised that the angle made by the axis of the terrestrial poles with the axis of the poles of the Ecliptic, far from remaining constantly equal to itself (the amount was 23° 27' 30" in the middle of the present century), varies by 0".48 yearly, and that this angle itself experiences a variation whose mean value is 48" in a century. It sometimes exceeds this mean value, and sometimes falls below it, by an amount which rises to nearly 9".65. Thus, while describing, in an interval of 25,000 to 26,000 years, its curve around the poles of the Ecliptic, the earth's axis describes, from east to west, a small ellipsis in the space of about eighteen and two-third years, and imperceptibly changes, moreover, its angle of inclination.

But, in fine, what is the true cause of all these movements?

Were the earth a perfect sphere, were all its radii of equal length, the effect of the universal ponderation would make itself felt as if all the material molecules were concentrated at a single point—the centre; and, apart from this ponderation, which exercises itself in the direct ratio of the masses, and in the inverse ratio of the square of the distances, nothing exists which would sway our globe in one direction rather than in another,—no precession of the equinoxes would take place, the plane of the Ecliptic would invariably coincide with the plane of the Equator, and an eternal spring would smile on the fortunate earth. The dream of the poet would be realised, and light would spread

But, as observation shows, the contrary has taken place, since, besides its movements of diurnal rotation and annual revolution, the earth has its mobile axis, which is independently inclined and displaced. Thus, the material molecules of the planetary surface are not all at an equal distance from the centre; and, consequently, the earth is not a perfect sphere. It is, as D'Alembert has demonstrated, the bulging, equatorial portion which experiences, owing to the solar attraction, a retrograde movement, carrying onward the rest of the globe in a general march, called the precession of the equinoxes.

But this general movement, as we have seen, is, in itself, simply the mean of a series of oscillations, which D'Alembert has also connected with gravitation. He has shown that the nutation of the earth's axis results from the moon's attraction on the bulging portion of our globe. Finally, it has been mathematically demonstrated that the said bulging portion of the earth produces, under the continuous action of the sun, the precession of the equinoxes; just as this portion determines, by its continuous action, the nutation of the lunar axis. As in this universal ponderation all the wheelwork of the world catches (tous les rouages du monde s'engrènent), and the planets, such as Mars and Venus, must also have their share in the action, however weak it may be, we have contrived to render an exact account of the slow changes of the obliquity of the Ecliptic.

Let us resume. Movement and matter, all is ponderated.

Inasmuch as matter is unequally distributed around the earth's centre, being flattened at the Poles and bulging at the Equator, it follows that the sun's enormous weight makes it vacillate, so that it describes at its axis a cone around the poles of the plane of its orbit. Its movement we see in the heavens in the precession of the equinoxes. But the terrestrial axis traces it tremblingly, because the moon, owing to its vicinity, exercises a perturbing action on our planet, which, in its turn, exercises on the moon a still more energetic influence.

CHAPTER II.
WHAT MAY BE SEEN UPON THE EARTH.

A solemn moment is it when the sap—that life-blood of the plant—arrested by the icy grasp of winter in its circulatory movement—receives a new impulse through the vivifying action of the central luminary of our system. What a subject for study and reflection!

It has been very finely dealt with by Longfellow.

How wonderful! he exclaims,—and we only regard the wonder with indifference, because it is repeated annually,—how wonderful is the advent of spring!—the great annual miracle, as he calls it, of the blossoming of Aaron's rod, repeated on myriads and myriads of branches!—the gentle progression and growth of herbs, flowers, trees,—gentle, and yet irrepressible,—which no force can stay, no violence restrain,—like the influence of love, which wins its way, and cannot be withstood by any human power, because itself is divine power. True enough it is, that if spring came but once in a century, or burst forth with the terror of an earthquake, and not in silence, what wonder and expectation there would be in all hearts to behold the miraculous change! But now the silent succession suggests nothing but necessity. To most men, only the cessation of the miracle would be miraculous, and the perpetual exercise of God's power seems less wonderful than its withdrawal would be.

May we venture on another quotation? We take it, gentle reader, from a living poet, whose works are not so widely read as their genuine poetical feeling and wealth of language deserve—I mean Sydney Dobell.

After describing the return of Spring, and her grief and astonishment at the spectacle of earth, pale, frozen, seemingly dead, he continues,—

We think that the ancients, if they had seriously reflected upon the important part played by the sun in the economy of nature; how it is the heart, and spring, and inner power of every movement and manifestation of life; how it is, as Sir David Brewster says, the centre and soul of our world, the lamp that lights it, the fire that heats it, the magnet that guides and controls it, the fountain of colour, which gives its azure to the sky, its verdure to the fields, its rainbow-hues to the gay world of flowers, and the purple light of love to the marble cheek of youth and beauty;—we think that the ancients, if they had thought upon, or had known, all this, would not have given the earth a chief place in our system. And that they did so is all the more strange when we remember that they attributed to the world a soul (the "soul of the world" is a favourite idea with the great philosophers of antiquity), and looked upon the planets as living creatures.

But they were swayed by that egotistical instinct which leads man to refer everything to himself, even the very gods which he has created after his own image. The Bible teaches us that there is but one God. Alas! are there not as many gods as there are men? Does not each of us create a deity in accordance with his own inclinations, his mode of thought, his degree of mental culture, the sphere of his ideas? Is the God of a tolerant philosopher identical with that of a bigoted fanatic? It is not so much due to a deceitful appearance, an optical illusion, as to a kind of innate infatuation, that the human race have come to consider the planet they inhabit as the centre of the universe.

Causes of the Circulation of the Sap.

Let us return to the sap, the life-blood of vegetation.

How is it that its movement does not recommence at the same time in all plants? Why are some clothed with leaves when the others are scarcely budding? Wherefore, in certain genera, do the flowers appear before the leaves?

Some authorities assert,—but facts show it to be a purely gratuitous supposition,—that the flower, which, with the fruit, seems to be the goal or object of vegetation, demands a greater activity on the part of the sap. But, in truth, many trees and shrubs, such as the poplar, the willow, and the hazel, flourish at an epoch when the sap is barely aroused from its protracted lethargy.

These are questions which have still to be answered.

But upon yet another question we may dwell at some detail. What is the cause of the circulation of the sap?

To the best of our knowledge, this important problem has never been propounded as it should have been. And for this reason: all observers who have taken up its consideration have had in view only the rising sap, and the cause of its rising. Evidently this is but a part of the problem. The ascending sap, after undergoing an important modification in the leaves, becomes the descending sap; just as the venous blood is transformed, on coming into contact with the air in the lungs, into arterial blood. It is this alternative movement of going and coming which constitutes the circulation both of the sap and the blood, and which ceases completely only with the life of the plant or the animal. We must, therefore, bear in mind,—which has not been hitherto done,—these two opposite, yet indissolubly connected, movements, before we can approach with advantage the solution of the proposed question.[40]

Science consists in discovering, among the different ways of looking at things which present themselves to the mind, the one which appears to explain most clearly the phenomena submitted to observation. He who doubts the accuracy of our remark need only join us in reviewing the different opinions enunciated up to the present time on the cause of the rise of the sap.

Grew, an English botanist, a contemporary of Newton, and his fellow-member in the Royal Society of London, attributed the rise of the sap to the play of the utricles of which the plant is composed. These utricles, he said, maintain a close intercommunication; through their contraction, the sap passes from the lower to the upper, and thus arrives almost at the top of the plant. Grew's authority carried conviction to the minds of many botanists, particularly to those of his compatriots. Yet was his opinion altogether imaginary; the supposed contraction of the utricles does not exist.

La Hire, a French botanist, who flourished at the beginning of the eighteenth century,—son of the geometrician of the same name,—pretended that he could account for the rise of the sap by the play of the little valves with which the interior of the sap-vessels was furnished; at the same time he assigned a very active rôle to the fibres of the roots. The fibres elevate, he said, the whole column of superimposed liquid, incessantly introducing, by a kind of suction, new fluids into the organs.

Unfortunately, the "play of the little valves, with which the interior of the sap-vessels is furnished," is a pure invention of La Hire's. Instead of growing wise by experiment, he suffered himself to be led astray by a false analogy. Valves are found in the veins of man and the mammals; but no one has ever seen the sides of the vessels of a plant garnished with valves to induce a circulation of the sap.

Mariotte, so well known by his researches into the compressibility of air, represented the rise of the sap as dependent upon what he called "the attraction taking place in the narrow tubes"—upon what, in fact, we now term capillarity. "This first entrance of water into the roots is in obedience," he said, "to a law of nature; for wherever very narrow tubes exist which touch the water, it enters into them, and even rises, contrary to its natural inclination."

Many botanists adopted the opinion of Mariotte. But if it were well founded, all capillary bodies, even inorganic ones, ought to present a circulatory movement analogous to that of the sap. Now, this is not the case. A body must be animated, must be living, for attraction to take place in the narrow tubes, and to produce a movement comparable to that of the nutritive liquid.

Malpighi attributed the rise of the sap to the alternating rarefaction and condensation of this liquid by heat; Perrault, to a kind of fermentation; De Saussure, to a peculiar irritability of the vessels. Of these three hypotheses, the first is purely physical; the second, chemical; the third, vital. So, as we see, there is something for everybody—chacun à son gout!

The same question has, in our own day, been taken up from a new point of view, on the occasion of Dutrochet's discovery of the endosmose. This philosopher was one of the first to perceive that two liquids, separated from one another by a membrane, quickly effect or induce a current which always carries the thinner liquid towards the denser, and ends by mingling the two completely. "It is endosmose," he said, "which produces at one and the same time the progression of the sap by impulsion, and its progression by affluxion. The sap would receive its impulse in the spongioles of the roots; thence would be carried towards the upper parts by the turgescence of the organs—by the affluxion, which would thus act as a forcible mode of suction."

The basis of this theory is, that the sap contained in the upper parts will be more concentrated or denser than that in the lower portions of the same plant. But this is a mere supposition. And even this supposition has been swept away by the recent experiments of Hartig and others, which show that the difference in density between the two saps is not only almost null, but in many ligneous plants the lower sap is, on the contrary, denser than the upper.[41]

Finally, and more recently, M. Joseph Boehm has put forth a theory which offers some points of analogy with that of Grew. According to Boehm, the rise of the sap is the effect of a suction, the cause of which must be sought both in the atmospheric pressure and in the transpiration which takes place through the organs, and notably through the leaves of the plant. The part which he attributes to the cellules, of which the organs are composed, he thus describes:—"When the superficial cellules of the plant lose water by transpiration," he says, "of two things, one will happen: either these cellules will contract and shrivel, or they carry up, by a kind of aspiration, to the neighbouring cellules, situated in deeper layers, a quantity of water equivalent to what they had lost. In the normal condition, the latter is always the result; each cellule takes from its neighbour what itself has lost, and this action, becoming more and more general, is continued from the leaves to the extremities of the roots. The cellules of the spongioles replace the water which they have yielded, from the humid medium surrounding them."

In support of this theory,[42] M. Boehm has made several experiments, which, we fear, will not carry conviction to every mind.

In the different theories which we have been attempting to explain, their authors, as it seems to us, have neglected an essential element—the life of the plant. Then, the experiments undertaken by way of proof, have been made upon cut stems or branches, which, consequently, did not enjoy their integral vitality. In fact, the results indicated could just as well have been obtained with inert as with living matter.

Taking into account all these considerations, we are doubtful whether any value can be placed on the theories just enunciated. Undoubtedly, physical causes, such as capillarity, heat, evaporation, atmospheric pressure, electricity, have a certain marked and constant action. But this action is here complex; it is found combined with a new force, whose effects constitute precisely the profound difference which exists between the massive mineral framework of the globe and the transitory beings peopling its surface. It matters little whether we call it vital force, or otherwise; sufficient that it exists. We must, therefore, allow for its influence when endeavouring to explain the varied movements of which plants, as well as animals, may be the seat.

A.—Plants.

The Daisy (Bellis perennis).

Among all the treasures of the floral world, that which should excite in each of us the tenderest emotion, and most readily stir up in our minds thoughts too deep for tears, is the Daisy,—that favourite of our innocent and happy childhood.

Ah! would we were now as content with simple joys as in the days when that wee, modest, crimson-tipped flower was to us a beauty, a prize, and a charm!

We wonder how many of our poets have done homage to the sweet and simple "nursling," or rather, whether by any true poet it has been neglected. Cowper reminds us that in

the village-wife and her little ones go forth to

James Montgomery, whose admiration of nature is somewhat frigid, can yet remind us that—

Chaucer warms into enthusiasm when he thinks of its pastoral, innocent gracefulness ("simplex munditiis"):—

Let us not omit a reference to quaint but genial William Browne:—

Yes! let no poet be taken to your heart of hearts who has no love for the "flower white and rede,"—in French, called "La Belle Marguerite,"—

—Burns's "bonnie gem,"—the flower of the meadow and the lea, of the woodland and the vale.

A modest, unassuming flower, destined to be trodden under the feet of the thoughtless, it withstands the rigorous breath of winter, is beautiful throughout the circle of the year—Bellis perennis, as the Swedish botanist not infelicitously called it. Its vegetation is arrested only during the harshest frosts; but it resumes its living growth as soon as it becomes sensible of the first rays of the spring-time sun.

It is at the moment of nature's awakening, about "the solemn Easter-tide," that this "sweet nursling of the vernal year" displays all the simple coquettishness of its chaplet of flowers,—that chaplet which has also procured for it the name of the tiny "Marguerite,"—that is, "little pearl,"—a name which the French have adopted from the Latin—Margarita.

Here let us pause, and propound a question.

How would you propose to test the real character, the genuine nature, of friend or acquaintance?

Your answers, dear readers (believe me, I hear them clearly!), are very various. Some of you say, that the best means of sounding the depths of the human heart is by bringing before it a misery which needs to be relieved. Others recommend the bestowal of a benefit. But such processes of analysis appear to me far from being infallible; too wide a margin is left for the operation of sentiments of pride or vanity. Why not conduct the man whose real character you wish to discover into a meadow enamelled with sparkling daisies? Thus you would impose upon nature the task of interrogating him. If he manifest feelings of indifference, you will do well to regard him with suspicion: take care how you admit him into your intimacy; for his heart must be cold, and his mind troubled—