Chapter IV: Part 4

The sea is a general name given to all the greater collections of water throughout the world, although, in a restricted sense, it is applied to those tracts of water of a secondary size, as the Black Sea, the Baltic, and the Mediterranean, the term "ocean" being applied to the larger tracts of water, as the Atlantic Ocean, the Pacific Ocean, &c. All the great oceans and seas unite, and, in reality, form one great world of waters, spread out and covering all the lower parts of the earth, the term "lake" being applied to collections of water surrounded by land, although the Caspian Sea retains the name of sea, and some of the great lakes of America may well deserve such a name.

The waters of the sea fill up all the lower parts of the earth, so that, almost without exception, the land is higher than the water, and as the land in some places rises but a few feet, and in others as many thousands, so, beneath the sea, the land sinks in many places but a few feet, and in others perhaps as many thousands as it is known to rise above it. The sea always maintains the same general level, although in past ages the land has risen and fallen, sometimes in one place and sometimes in another; indeed, the same process is taking place every day, but in so slow a manner that centuries are required to make any great alteration; while some tracts of land are being encroached on by the action of the waves, others are being added to and elevated by accumulations of mud and sand, or raised by the action of earthquakes and volcanoes, which throw up under the sea, as well as on the land, vast quantities of melted earth or lava, forming strata known to geologists as basalt, tufa, &c., or eject showers of ashes and dust in such prodigious quantities as to cover many hundred square miles of the earth's surface. It was by one of these showers of ashes from Vesuvius that the cities of Herculaneum and Pompeii were buried. So that, as a whole, although the sea is continually altering slowly its position, yet it pretty equally maintains the same elevation. At first thought it may be supposed that the rivers constantly flowing into the sea would alter its level, for some are so large that millions of tons of water are brought by them into the sea every hour, and there are thousands of rivers and rills which, night and day, pour in their tribute of waters; but God has wisely and kindly arranged these things (like all others) so that they shall afford us innumerable comforts, and yet not raise up the sea so that it shall cover the land, for it requires but a moment's consideration to be convinced that all this water which flows into the sea must first have been abstracted from it, and it is in this way--when the winds blow over the sea, they absorb or take up a certain quantity of the vapour which continually rises from it; for air absorbs a certain quantity, and a certain quantity only, of the vapour of water; but this quantity is determined by certain circumstances, for instance, the warmer the air, the more it will absorb, the less the pressure on the air, the more it will absorb, and the drier the air, the more it will absorb, that is, the less moisture it has already got, the more will be required to make up that quantity which the other circumstances permit it to contain. Now, what takes place if a warm, dry, light current of wind blows over the sea, landward? Why, all the vapour given off by the sea, to the amount of millions of gallons, is absorbed and carried inland by the wind or current of the air, and this continues onward, laden with moisture, until it meets with one of the several circumstances which shall cause it to be incapable of holding the quantity of moisture which it has already got; for instance, it meets with another current of air colder than itself, these mingle, the vapour of water is condensed by the cold, and a cloud is formed. This consists of minute particles of water suspended in--not absorbed by--air; these particles gradually collect, and down falls the rain on to the earth. This drains off from the surface, forming rills, which collect as they descend, by their own weight, into the lowest channels of the ground, and form into streams and rivers, and back into the sea comes the water which the air had taken away, with this difference, that it is free from salt and fit for the many uses to which fresh water alone can be applied; when the vapour rises from the sea, none of the saline matters rise with it, for, although the water is volatile, yet they are not, and this is the whole source of fresh water. It is distilled in the great laboratory of Nature, and gives nourishment to all the living beings who dwell on the land and in the rivers and lakes; or the rain may sink into the earth and be carried for miles and miles under ground, running through some porous stratum, such as gravel, until it flows out in the form of a spring, bubbling up amongst flowers and weeds, and forming the source of some river, which receiving the rain and all the springs in the country through which it flows, finds its way back into the ocean at last.

This is the way in which all rivers and streams are formed. An enormous extent of land thus drained gives rise to thousands of rills, which collect into streams of goodly size, meandering through valleys and pouring their tribute of waters into a main stream, which at last accumulates by additions to its course, and becomes one of those great water-courses which form the highway through a continent. The Amazon, Hoang-Ho, Ganges, Nile, Danube, and Volga, may be cited as some of the greatest water-courses and highways of civilisation. These great rivers are navigable for large ships, even for many hundreds of miles, and it is most fortunate that this navigation is so seldom impeded by falls; for these, although among the grandest and most beautiful objects of nature, yet put a stop to the navigation of a river which would otherwise be passable for hundreds of miles further. Rivers which run through districts subject to periodical rains, or those whose sources lead from mountain slopes where vast quantities of snow are deposited in winter which melts on the approach of summer, are at such seasons of the year suddenly augmented, and generally overflow the banks and inundate the country for miles. This is in many cases a very great misfortune, as it spoils the land, reducing it to a swamp, but not in every case; the overflowing of the Nile brings down with it a great quantity of fertilising vegetable matter, and serves to manure the whole district, for the soil being extremely porous and the heat great, the moisture is soon got rid of, and hence it was a custom of the Egyptians to celebrate the rising of the Nile by feasts and ceremonies.

Lakes are formed in the same way as rivers, but, being surrounded by high land, have no outlet for the waters so that they may flow back into the sea. If a lake were about to be formed it would be in this way--the rain descending on the surrounding high lands would run in rills to the lowest part, and there collect, forming a pool which would gradually increase in size as the water flowed into it, this increase continuing until the surface became so large that the evaporation from it exactly equalled the supply, it would then extend no further, but remain a permanent lake or inland sea, giving off vapour to refresh the surrounding country, and again receiving it back by streams and rivers, as does the ocean.

There is scarcely a spot known on the surface of the earth, which does not show strong evidence of having, at some former period, been the bed or bottom of some sea or lake. Some of these evidences may be seen in the strata or layers of earth forming the sides of the cliffs which abut on the sea-shore, and which could not have been produced by any other agency; these strata contain so many marine shells and other matters peculiar to the sea, that the fact does not admit of doubt that they were there produced. These same strata are met with throughout the land; in sinking wells and mines, the same strata are cut through, and have a known and uniform succession, with but few exceptions; the cliffs, however, are the most convenient places to see these strata. That the same process of alteration in the position of the water and land is still going forward, is shown by many evidences, such as towns which were once on the sea-shore, being now some distance from it, as the City of Norwich, and in other cases the reverse. The chalk cliffs at Dover, Ramsgate, &c., show the action of the sea in the corroded state they present, and slips or falls of great masses which have been undermined by the sea, are frequently occurring.

The ancient town of Ravenspurn, at which Henry IV. landed, has entirely disappeared, and others, recorded to have been situated on the shore, have now only their names left. The parts of the shore most rapidly corroded by the sea, are those composed of sand, chalk, and clay, while those composed of the harder kinds of sandstone or of granite, have been but little wasted away, so that they project and form the headlands, while in many cases deposits of mud have extended them. There are many other causes which determine the elevation or depression of the land, besides the action of the sea and earthquakes, such as winds, frosts, &c.

The slightest movement of the air communicates motion to the surface of such a great sheet of water as the sea, and this motion is gradually increased till one ripple meets another, and the power of both goes to form the next, so that they acquire a very considerable size; when a gale of wind blows, the rolling of the waves far out at sea becomes terrific, and they rise like mountains, chasing one another over the wide ocean. But sailors rather like a smart breeze, and more especially did they a few years ago, when the wind was all they had to depend upon for onward progress. In those days a calm which would sometimes last for weeks together was to them most fearful, for it was often a source of great distress and privation, especially if short of provisions; the sea would then look like a great pool of stagnant water covered on the surface with sea-weed and animalculæ, and fearful it must have been when food was failing, and no hope of progressing but the springing-up of a wind. But, in these days, with the assistance of steam, a calm is the very time in which most progress is made, and there is no doubt but a time will come when it will be matter of wonder that men could ever have trusted to so uncertain an element as the wind; yet, if it were not for the winds, currents, and tides, the sea could not maintain its state of purity, for its saltness is not sufficient to prevent the growth of fungi and all sorts of animalculæ, which, from their decay, would produce noxious gases and be most injurious to animal life. Its constant motion alone prevents this, and the spores and germs are tossed about until destroyed and eaten up by the inhabitants of the deep who devour every kind of organic matter which is deposited in the sea, and thus it is that the waters of the ocean are so bright and clear that an object can be seen at a considerable depth.

That the constant currents of the sea prevent the formation and growth of sea-weed, is clearly shown by the great "Sargasso Sea," or tract of weed (_Fucus natans_), called the Gulf-weed. This great tract embraces thousands of square miles, and is situated in the very middle of the Atlantic Ocean, where there are but few currents; but surrounding it is the Gulf-Stream, an enormous current of water running at a regular rate of four or five miles an hour. This Gulf-Stream is supposed to be caused by the same laws and influences which determine the trade-winds, namely, a constant rarefaction of the water at the tropical parts of the earth, and a corresponding condensation at the Arctic portions, for warm water is much lighter than cold, and when the waters of the tropical regions become lighter the heavier waters of the cold regions pressing down more forcibly tend to raise them above their proper level; they therefore flow towards those very parts which have sunk down by their contraction, and a constant current takes place--this current is the Gulf-Stream. It runs from the Gulf of Mexico northwards towards Newfoundland, turning by Iceland towards the British Isles, by France and Spain, onwards to the coasts of Africa and South America, the West Indies, and again to the Gulf of Mexico, although the return current does not go by the name of Gulf-Stream. This great stream of water warmed by the tropical sun serves the same two purposes described under the section "Air" as being fulfilled by the trade-winds, namely, a circulation and distribution of the superfluous heat of the equatorial regions, warming the northern countries and cooling by the return of under-currents those in the tropics. The fogs of Newfoundland are caused by the great current of warm water entering the cold region and carrying with them surface-currents of moist air, which the cold condenses into fog, just as the breath is visible in a cold atmosphere. England owes its moist and mild climate to the same cause.

The sand which lies upon the sea-shore is produced by the action of the waves constantly dashing against the earth and rocks of the coast, and is mostly composed of what chemists call "silex," or silica, which is a chief constituent of most rocks and earths; these, being worn down by the action of the waters, form sand. The fragments of these rocks (especially granite) and those which contain silica in the form of minute crystals, are soon rolled and rubbed together until they are ground to powder, but it is doubtful whether any sand exists at the bottom of the deep seas far from shore, as the waters there lie--and must have laid--perfectly quiet ever since they were seas, for the greatest storm that ever rages does not affect the tranquility of the sea more than a few fathoms beneath its surface, so that a stone dropped in the middle of the Atlantic Ocean, could be picked up after a hundred years exactly where it fell, were it possible for any to find out the spot and descend; but the bottom of some deep seas, as in the antarctic regions and the north Atlantic Ocean (as the soundings between Ireland and America have lately shown), is covered to an unknown depth with what had been supposed to be sand, but which is not sand at all, but a wonderful collection of minute shells and coralines, which to the unassisted eye have the appearance of sand. They are the silicious shells and coverings of minute vegetables and animals, these creatures, being coated with silica (a substance indestructible by age and the action of water), fall to the bottom of the sea and there accumulate in such countless myriads that they form this fine substance, long mistaken for sand, but between which, in reality, there is a marked distinction, the one being formed by the disintegration and grinding-up of rocks, the other the product of organic life; this, when it has accumulated for ages, will, in all probability, form some island or part of a continent, and be the site perhaps of some magnificent city, reared upon a foundation of these minute wonders of the deep, whose skeletons will have become consolidated into a hard and compact stone, of which its houses and churches will, in all probability, be built.

This is not imagination, as such occurrences have really taken place--all our chalk cliffs and downs constitute part of an immense stratum. Now, every grain of this chalk contains and is made up of thousands of minute shells and corals. These chalk downs were once the bed of some ocean which, in all probability, was filled up by their remains.

What are the railroads and works of men's hands compared with this? Of this chalk (hardened by pressure into limestone) most of our public buildings are constructed, or (changed by pressure and heat into marble) our statues of great men have been carved. What a mockery to choose marble as the medium of rendering our heroes immortal--itself the very type of mortality, being formed by the death of millions of creatures.

In Dr. Carpenter's work on the microscope occurs the following:--

"Thus, when we meet with an extensive stratum of fossilised _Diatomaceæ_, in what is now dry land, we can entertain no doubt that this silicious deposit originally accumulated either at the bottom of a fresh-water lake or beneath the waters of the ocean, just as some deposits are formed at the present time, by the production and death of successive generations of these bodies, whose indestructible casings accumulate in the lapse of ages, so as to form layers, whose thickness is only limited by the time during which this process has been in action.

"In like manner, when we meet with a limestone rock entirely composed of the calcareous shells of Foraminifera--some of them entire, others broken up into minute particles--we interpret the phenomenon by the fact that the dredgings obtained from certain parts of the ocean-bottom, consist almost entirely of remains of existing Foraminifera, in which entire shells--the animals of which may be yet alive--are mingled with the debris of others that have been reduced by the action of the waves to a fragmentary state.

"Now, in the fine white mud which is brought up from almost every part of the sea-bottom of the Levant, where it forms a stratum that is continually undergoing a slow but steady increase in thickness, the microscopic researches of Professor Williamson have shown that not only are there multitudes of minute remains of living organisms, both animal and vegetable, but that it is entirely or almost wholly composed of such remains."

The water of the sea is everywhere salt, except at the mouths of great rivers, where the quantity of fresh water displaces that which properly belongs to the sea. The cause of its saltness is the solution of a natural mineral (chloride of sodium) which exists in the earth in great abundance in layers of a crystalline structure, and as this chloride of sodium (common salt) is soluble in water, of course it is all dissolved by the water in whatever situation they may come into contact with each other. The composition of sea-water differs slightly in different parts of the earth, the southern seas being slightly more salt than the northern. As a general rule, about five per cent. of solid matter is contained in sea-water, of this rather more than half (5.7) is chloride of sodium; the greater part of the other half consists of different salts of magnesia, and this is the whole source of the medicines known as Epsom salts and magnesia, the former being the sulphate and the latter the carbonate of magnesia. Iodine, another article used in medicine and photography, is also extracted from sea-water, which however contains but a very minute portion, too small to be detected as a general rule, but extracted by burning certain sea-weeds, in the ashes of which it is found in sufficient quantity to be separated.

Although the sea as a whole keeps its level, yet in various parts it is constantly rising and sinking, sometimes at one place and sometimes at another; these risings and fallings are called tides, and are caused by the joint action of the sun and moon, that is, by their attraction, acting at different distances. First it must be observed (as is well known) attraction varies inversely as the square of the distance, that is, if the moon were twice as far off, her attraction of the earth would be one-fourth of what it now is, if three times as far off, one-ninth, and so on.

The moon's average distance from the centre of the earth (A to C, in the diagram) is about 240,000 miles, or about 60 times the earth's radius (B C), which is a little under 4000 miles, consequently if the distance from the moon to the centre of the earth (A C) be expressed by 60, the distance to the nearest surface (A B) will be 59, and the farthest surface (A D) 61. The moon will attract the point B with a force of 1/59^2 or 1/3481, the point C with the force of 1/60^2 or 1/3600, and the point D with the force of 1/61^2 or 1/3721. Now as the force at C is greater than at D, the earth itself will be pulled away from the water at D, and leaving it a little behind, will produce a high tide there, this tide is known as the "inferior tide" (2). Again as the force at B is greater than at C, the water at B will be pulled away from the earth and produce a still higher tide, called the "superior tide" (1), or that which takes place when the moon is due south. This heaping-up of the waters by the moon, to the height of 4-1/2 feet (on an average) causes corresponding depressions to the same depth in those parts of the earth which are situated between the raised parts, making a difference between high and low-water of nine feet due to the moon; precisely the same effects are produced by the sun, but though his attractive power is so much greater than the moon's, his distance is also so much greater, that the heap of water he can raise is somewhat less than 2 feet, and makes therefore less than 4 feet difference between high and low-water, due to the sun. When the sun and moon are both on the same side, or on opposite sides of the earth (as at new or full moon), then the attraction of both act together and produce "spring tides," with a difference of 13 feet; at first and last quarter the sun and moon oppose each other, acting in cross directions, and the difference is then only 5 feet. But these effects could only take place in the wide open space of an ocean, and when other forces do not interfere, such as obstruction to the tide-waves by land, &c.

Inland seas (as large as the Mediterranean even) have but very little tide, while pinched-up rivers may have a great rush of tide, as at Bristol, where it rises to 45 feet sometimes, and at Anapolis in Nova Scotia, to so much as 120 feet! Wind will also accelerate or retard both the speed and height of the tides. London receives a much greater tide than its due, for the tidal-wave being interrupted by Ireland and England, rolls up the western coast (taking a northerly direction) with such force as to swing round the Shetlands and all down the eastern coast of Great Britain. The direct Atlantic wave also, when split by our island, rolls along the south coast from Land's-End to Dover, rushes through the "Straits," and meets the backward wave which has been travelling round by Scotland (as before mentioned), the two then pour into the Thames and give an otherwise quiet river a high and useful tide; so that London receives two tides, the southern one nearly 10 hours after Cornwall, and the roundabout one not till nearly 23 hours after it first reaches England.

The waters are the great highway throughout the whole world, and what an easy transit it has formed to those nations sufficiently civilised to require a further knowledge of the world, and thence procure for themselves luxuries not obtainable at home--at the same time, spreading civilisation wherever they go!

If the oceans, instead of forming one great concourse of waters, had existed in the form of inland seas or great lakes, the great chains of mountains, deserts, and uninhabited tracts of earth, would, in some cases, have formed impassable barriers, whilst in other parts civilisation would have been impeded from the easy access of the more savage tribes, who would have despoiled the more fortunate by inroads amongst them, mingling with or exterminating them, and checking the onward progress of civilisation. And this has always existed where great tracts of land are, which are the last parts of the world to be civilised, and in many parts remain as rude as they were thousands of years ago. All this is owing to the good and wise arrangement of water and land, and is an instance of the care and foreknowledge of God, who has provided for the onward progress of that creature to whom alone such a progress has been allotted; but as they now exist the oceans form impenetrable barriers to the savage, so as to restrict his brute force and uncultivated habits spreading, while they form easily-traversed highways to the more civilised nations, enabling them to spread their civilisation without contamination to themselves, but to the advancement of others.

The oceans are now navigated by thousands of vessels engaged in mercantile objects, and it is perfectly astonishing with what rapidity and safety these great tracts of water are crossed.

In one of Chambers's "Papers for the People," called "Ocean Routes," is the following, speaking of the perfecting of the steam-vessel:--

"The regularity, speed, and safety with which the voyages of these vessels were made, soon pointed them out as the best conveyance both for passengers and the mails.

"In 1821 they were employed on the latter service between Dublin and Holyhead, and between Calais and Dover; and now, with few exceptions, all the channel and ocean-work of the Post-Office is done by steamers, and all the passengers and much of the goods' traffic between the parts of Great Britain and Ireland, have been within the last quarter of a century transferred to them.

"After the steamboat had thus passed through the various stages of infancy and childhood--had tried its strength on English rivers, in the Irish Sea, and in the British Channel--men began to ask, was it not strong enough and old enough to do more? Could it not cross an ocean as well as a channel--take letters and men, and merchandise to America, India, and Australia, as well as to Ireland and France? In this question were involved considerations of the highest importance to all the world, but particularly to this country, for no other country has such extensive foreign possessions as Great Britain, or carries on such an extensive trade.

"With the exception of the United States, all the colonies planted by the British remain parts of the empire, while Spain and Portugal have lost nearly all those rich territories, extending over the fairest portion of the American continent, that at one time acknowledged the sway of the houses of Bourbon and Braganza. The foreign possessions of France are insignificant, and, of the other nations of Europe, the Dutch alone possess a territory abroad greater than they have at home.... The proud position of Britain among the nations, the necessities of her foreign trade, and the wants of her colonies and dependencies, apart from all other considerations, rendered it fitting and natural that she should lead the way in maritime enterprise, and teach the nations how to navigate the ocean by steam.

"Nor has she failed in this high task; for, within thirteen or fourteen years, since the question was first proposed, she has established lines of gigantic steam-vessels that are now traversing with regularity and safety every ocean, steaming altogether more than a million and a quarter miles every year, and distributing letters and newspapers all over the world, at a cost to the country of about £650,000 per annum."

The rapidity and ease with which thousands of troops were lately conveyed to the Crimea and India, together with all their stores, horses, &c., form one of the most wonderful feats of ocean navigation ever performed, and point out the beauty of those arrangements which enable man to traverse the whole earth, whether by land or by water, so that it may fairly be said that the civilisation of the world depended and still depends upon the waters.

INTRODUCTION TO THE ORGANIC KINGDOMS OF NATURE.

The foregoing descriptions refer to the great works of God as seen in those creations which possess not that most wonderful attribute--life. There is no limit in extent, in quality, or in number, to these works; their extension appears to be infinite; their magnitudes are large or small, just as we compare them one with the other. This earth is an enormous mass, contemplated in comparison with ourselves, but an insignificant speck when compared with the sun, and there are certain laws, chemical and mechanical, which govern them all--heat, light, and electricity permeate all the infinity of space--attraction exists everywhere. There are no individual existences among them; all are made up of matter combined according to certain definite chemical laws, and always obedient to them under the same conditions--moving according to certain mechanical laws, and always obedient to them. The Creator who made these lifeless masses made also the laws to regulate them; but, besides these, it has pleased Him to form certain other creatures not for an instant to be compared in size or quantity with the former, and made up also of certain chemical compounds obedient to the mechanical and chemical laws, with one more addition, that unknown, inexplicable attribute--life. This wonderful quality exists in all organic beings; they obtain by it individual identity; they are whole creatures--imperfect with any part taken away, also imperfect with any addition. Clay is clay, in any quality or form; iron is iron, whether a grain or a ton; but a tree is only a tree when it is complete. We cannot say "some tree," as we would "some clay," it must be _a tree_, or several trees, each a separate and complete existence--perfect in itself--made up of solids and fluids, and possessing certain attributes, namely, a constant circulation of its fluid parts, a constant appropriation of food and rejection of waste matters--growth thereby to a certain definite form, and in many a definite size, together with the production of germs, capable, under certain conditions, of producing beings exactly similar to themselves. This constitutes organic life, and is possessed by all vegetables. Animal life is exactly the same, with the super-addition of will or mind in its most perfect state, of instinct or some analogous function in its lower states, or in quite the lowest--a chemical and mechanical difference only, such as shall determine the choice of food and mode of assimilating it. This difference consists in the vegetable feeding upon inorganic food, and the animal on food which has received the stamp of organisation. Creatures possessing life, whether vegetable or animal, are called organisms. It is found that these organisms are made up of certain atoms united in larger multiples than in inorganic substances, which are either simple or compounded of but few atoms; thus water is composed (every atom of it) of _one_ atom oxygen, united to _two_ of hydrogen. Common salt (every atom of it) is composed of _one_ atom of the metal sodium with _one_ atom of chlorine. Chalk is compounded of _one_ atom of calcium in union with _one_ of oxygen, and this united to one atom of carbonic acid, itself composed of one atom of carbon with _two_ of oxygen. But organic compounds are often made up of four or six elements, united in multiples of their usual combining quantities. Thus, grape-sugar is made up (every atom of it) of 24 atoms of carbon, 28 of hydrogen and 28 of oxygen; these 78 atoms unite and form one compound atom, of which the sugar is wholly compounded, and thus, from such a complex nature, it happens that most organic compounds are decomposed by even a moderate degree of heat--all by a heat equal to red-hot iron. From these facts, it may be therefore stated, that all organisms are complete in themselves, have definite lives or existences, appropriate certain matters to themselves, grow thereby, and are compounded of organic atoms.

THE VEGETABLE KINGDOM.

QUANTITY, DISTRIBUTION, AND OFFICES OF THE VEGETABLE.

In contemplating nature there are few things which give more delight than the beauty and variety of the vegetation which clothes the surface of the earth, whether it be that we contemplate the grassy covering of the plains of the Old World, or the immense "prairies" of the New, spreading out as it were into seas of grass, and giving food and shelter to thousands of wild animals; or gaze upon the rocky height of some vast mountain range, and see the gigantic oak or pine, forming by their wide-spread shades the solemn forest which extends for miles beneath us, and which forms a shelter for the various tribes of birds, monkeys, and other animals, to whom it is a home of happiness and plenty--under every aspect the contemplation of nature's clothing fills the mind with awe and admiration.

There is hardly anything more refreshing to the mind than the contemplation of trees and shrubs congregated into a wood, the floor of which is carpeted with mosses and flowers, where the gigantic and gnarled trunks of the forest trees covered with many-coloured lichens starting up all round, circumscribe the view, while the wide-spreading boughs and the leafy canopy overhead exclude the sun's rays. It is here that one views nature in her purest forms and colours, untouched by the destroying hand of artificial arrangement.

The immense preponderance of the vegetable over the animal world in quantity compensates somewhat for the superior organisation and the intelligence of the latter, which must be studied in the individual, while the vegetable world, which can be contemplated in the mass, almost overwhelms the imagination with its vastness. It is indeed impossible to compute the amount of vegetation in the great forests of America and Russia (in which latter country are the largest in the world), covering hundreds, nay thousands, of square miles with one continuous growth of timber. That forest in Russia through which the river Pechora flows, extends over a space of 150,000 square miles! The whole mass of animated existence sinks into insignificance when compared in quantity with this; and when to these forest-tracts are added the thousands of square miles of grass and heaths which grow in some climates with wonderful luxuriance, the amount of the vegetable kingdom is at once placed beyond all comparison with the animal kingdom in point of quantity. Cooper, in his American novels, describes the prairies as great seas of grass extending as far as the eye can reach, and rising to a height of 8 or 10 feet; and Humboldt describes some of the grasses on the plains of the Oronoco, as being so gigantic that they measure 18 feet from knot to knot, and says the Indians use them for blow-pipes to shoot their poisoned arrows from. And--as though it were not sufficient that the earth should bring forth everywhere all kinds of trees, shrubs, and grasses--the waters of the ocean itself are often filled with vegetable life; in some tracks the tangled sea-weed (_Fucus Natans_) is so dense as to impede the onward progress of ships for hundreds of miles together.

Humboldt, in his "Views of Nature," describing the two great banks of sea-weed, says: "The two banks of sea-weed, together with the transverse band uniting them, constitute the Sargasso Sea of the older writers, and collectively occupy an area equal to six or seven times that of Germany."

Nor is this the only vegetation which the great world of waters contains, for if we descend from the contemplation of its larger members we find them even surpassed in quantity by others of such extreme smallness, that they can only be seen individually by means of the microscope, but which exist in such prodigious quantities that the mind can hardly realise the fact. These vegetable atoms have been so increasing and depositing their minute coverings at the bottom of most parts of the ocean, that for hundreds of miles their beds are composed of nothing else, and it has been found that most of the great changes on the surface of the earth have been effected by these minute creatures and their companions of the animal world; for as we find chalk-downs and coral-reefs formed by the remains of microscopic animals, so productions of equal extent have been formed by the smallest members of the vegetable kingdom, chiefly the "Diatomaceæ," a race of minute vegetable productions which propagate by sub-division and have the power of withdrawing earthy matters from the waters in which they live, which forms a sort of shell or covering; this shell at their death remains indestructible and gradually accumulates in the bed of the sea (fig. 1). Examination of the various strata of the earth shows that chains of hills, beds of marl, and almost every kind of soil, whether superficial or raised from a depth, consist in a great proportion of the earthy remains of these minute plants. These tracts of land were once the beds of oceans which were thus gradually filled up. The waters of the Antarctic Ocean are often opaque and quite brown from the multiplicity of these creatures, the lead used on shipboard for sounding coming up from the bottom covered with what appears to be mud, but which on a microscopic examination proves to be nothing else than the shells of these and allied species (fig. 2). Thus we find the land and the waters are everywhere full of vegetable life; the air itself moreover is so filled with the germs of vegetable and animal creations, that it is quite impossible to exclude a portion so small that it shall not contain any; in proof of which, any organic substance set by for a few days in a vessel ever so carefully closed, is shortly covered with a growth of mould consisting of fungi, which under the microscope present most beautiful forms and colours (fig. 3). The cause of this is a deposit from the air of the spores or germs of these creatures, and the nature of the decomposing substance into which they fall often determines the race or tribe which shall come to life and inhabit it, showing plainly that but a few of these only among many come to maturity, just as when a variety of seeds are thrown on any particular kind of soil, only those to which the soil may be suitable come to perfection.

Dr. Carpenter in his work on the microscope says:--"There are scarcely any microscopic objects more beautiful than some of those forms of mould or mildew which are so commonly found growing upon the surface of jams and preserves, especially when they are viewed with a low magnifying power and by reflected light; for they present themselves as a forest of stems and branches of extremely varied and elegant forms, loaded with fruit of singular delicacy of conformation, all glistening brightly on a dark ground.

"The universality of the appearance of these simple forms of fungi upon all spots favourable to their development, has given rise to the belief that they are spontaneously produced by decaying substances, but there is no occasion for this mode of accounting for it, since the extraordinary means adopted by nature for the production and diffusion of the germs of these plants adequately suffices to explain the facts of the case.

"The number of sporules which any one fungus may develope is almost incalculable; a single individual of the "puff-ball" tribe, has been computed to send forth no fewer than ten millions. And their minuteness is such that they are scattered through the air in the finest possible dust, so that it is difficult to conceive of a place from which they should be excluded."

Pure water exposed to the air does not afford nourishment to the germs which fall into it till a sufficient number of them shall have been deposited to form a food for those which come after them; but if we mix with the water any soluble vegetable or animal matter, in a short time the microscope will detect the growth of the germs that are being deposited, for where nourishment is, there only can they be developed. These germs are capable of existing for an indefinite period, either floating in the water, or blown about by the air, and have been detected hundreds of miles from land, the rigging and sails of ships far away from shore are often covered with what sailors suppose to be sand blown from the land, but which are organic substances, either vegetable or animal. According to Humboldt, the Red Sea has derived its name from the fact that at certain seasons the surface of the water has a reddish appearance, and this (as he says) he was fortunate enough to observe, which colour he found to be due to myriads of red fungi which had formed on the surface. The seeds of some plants are furnished with minute wings or plumes which cause them to be borne on the air or floated on the water (fig. 4), to fertilise some barren spot, perhaps a coral reef which has at length reached the surface of the water and which ascends no higher, for the little creatures which built it are aquatic and cannot live exposed to the air; this coral reef now becomes a receptacle for sea-weed and fungi, which float on the surface of the ocean, are washed on to the reef, die, decay, and leave behind a thin layer of mould, which process being repeated again and again, forms an elevated edge to the reef, enclosing a lake or "lagoon" as it is called, the waters of which evaporate and the space is filled up in the same way as the edge was formed, together with the excrements of birds, &c., forming layer after layer of mould, and the surface becomes fit for the growth of larger seeds, as the cocoa-nut, banana, &c., which are drifted on to it by the waves; in this way a coral reef becomes an island fit to be inhabited by man and other animals.

The vegetable kingdom forms a mysterious link between the mineral and animal kingdoms, and binds all creation into one grand and unspeakably beautiful whole. There are certain substances from which the vegetable derives its nourishment, namely water, carbonic acid, and ammonia, which, though strictly inorganic, are yet not simple or elementary substances, but consist of pairs of elements combined. Thus water consists of oxygen and hydrogen, carbonic acid of oxygen and carbon, and ammonia of hydrogen and nitrogen. All these aliments of the vegetable kingdom exist in the air, and in sufficient quantities to supply all the requirements of vegetation; so that the air, together with a few metallic oxides (salts) derived from the earth, furnishes food for the whole vegetable tribe, from the highest to the lowest, and these vegetables in their turn supply all the food which the animal tribes consume, for although one animal feeds upon others, yet these must previously have derived their nourishment from vegetable matter. Vegetables not only supply food properly so called, but likewise that which is essential to respiration, for besides separating all noxious excess of carbonic acid from the air, they are an inexhaustible source of oxygen, the element essential to respiration, and consequently animal life. This supply of oxygen by vegetables compensates for that which is consumed in respiration by animals, and thereby maintains the atmosphere in a state proper to be breathed. That plants do thus absorb carbonic acid and give out oxygen, can be proved in the most certain manner, if the green parts of a plant be placed in water holding carbonic acid in solution, and exposed to sunshine; the carbonic acid will shortly be found to have disappeared from the water, while oxygen gas is evolved and can be collected, its quantity being exactly equal to the carbonic acid which the water contained.

Besides furnishing food and oxygen for the nourishment of animals, vegetables afford a shelter from the burning rays of the sun in hot climates, not only to man, but to those hundreds of wild animals whose proper home is in the forest. Humboldt says he found in South America forests composed of such close growth, that it was quite impossible even for the wild animals to penetrate into them, except at a few places, and that the jaguar often lives for weeks in the trees without descending to the ground, preying upon the monkey tribes and other animals, which are found in almost incredible numbers there; and Dr. Livingstone thus describes the forests of Africa:--"The forests became more dense as we went north. We travelled much more in the deep gloom of the forest than in open sunlight. No passage existed on either side of the narrow path made by the axe. Large climbing plants entwined themselves round the trunks and branches of gigantic trees, like boa-constrictors, and they often do constrict the trees by which they rise, and, killing them, stand erect themselves."

These woods, as well as the grass and herbage of the plains, afford an enormously extended evaporating surface, and act, in the heart of hot countries, as inland seas, giving out clouds of vapour, which ascend and are condensed in the form of rain; in this way the surface of the earth is cooled, the fluid (far away from its proper source, the ocean) is economised and fertilises a greater space of surface. Vegetation also acts in preserving the surface of the earth from those ravages which both wind and rain would otherwise effect; the great deserts have been levelled by these causes, the earth not being of a quality to support vegetation. Cattlin says, that in North America he frequently met with great conical-shaped mounds of earth devoid of vegetation, and which were fast being levelled by the rains, at every fall of which gullies were formed on their sides, down which the mud poured in streams; now, had these been of a quality to support a covering of grass, their size and form would have remained unchanged for centuries. Railway embankments are often sown with grass seeds, to prevent injury to them, especially where this covering is not likely to come soon, as in the vicinity of large towns.

Thus it is seen that the vegetable kingdom far exceeds the animal in quantity, that it is everywhere distributed, that it affords nourishment and shelter to animals, preserves the air fit for respiration, keeps down the excess of heat, and preserves the form of the surface of the earth.

MODE OF GROWTH--AGENTS AFFECTING--CONSTITUTION AND POSITION IN CREATION.

The green colour of plants is due to the formation and deposition in their cells of a peculiar compound called "chlorophyll," and it is ascertained that this compound is produced in the plant in consequence of its exposure to light, for no plant grown in the dark is green, but will become so when light is admitted. This is shown in many cultivated vegetables, as celery, lettuces, &c., in which by banking up the celery, or tying together the lettuce, the light is excluded, and the stalks of the one and the heart-leaves of the other become mild and white, whereas the same grown in a state of nature are so green and rank as to be almost poisonous.

The effects of light and heat in favouring vegetation being nearly always found in union, causes that which is really due to light often to be attributed to heat, as in the growth of tropical plants; where both are combined, there will be the greatest powers of vegetative growth. The absence of light and air often causes the upward growth of a plant to seek them; a curious instance of this, altering the habits of a tree, is mentioned by Dr. Livingstone, who says:--

"As we traverse a succession of lawns and open forests, it is interesting to observe something like instinct developed even in trees. One, which when cut emits a milky juice, and if met with on the open lawns grows as an ordinary umbrageous tree, and shows no disposition to be a climber, when growing in a forest still takes the same form, then sends out a climbing branch which twines round another tree until it rises 30 or 40 feet, or to the level of the other trees, and there it spreads out a second crown, where it can enjoy a fair share of the sun's rays. In parts of the forest still more dense than this, it assumes the form of a climber only, and at once avails itself of the assistance of a tall neighbour, by winding vigorously round it, without attempting to form a lower head. It does not succeed so well as parasites proper, but when forced to struggle for space, it may be mistaken for one which is invariably a climber."

The absence of heat with plenty of light is shown in the vegetation of mountainous districts, where there is great size, but the absence of leafy expansion, as in the pine tribe (fig. 5). Where both light and heat are deficient, nothing but fungi, mosses, and lichens of the most stunted nature will grow. Experiments in hothouses prove that although tropical plants be supplied with their proper amount of heat, yet without the very greatest supply of light that can be obtained, they do not come to any degree of perfection. The influence of light is chiefly upon the leaves, that of heat upon the earth and root, which becomes more fully developed. When a seed is placed in the earth, moisture is absorbed by it from the earth, and a development of the cells of the cellular tissue of which the seed is composed takes place, and from the peculiar nature of these cells they divide into two sets, one of which passes upwards towards the light, the other passes downwards into the earth; these last (which pass downwards) form a fibre called the "radicle" (fig. 6), those which pass upwards form also a stalk or fibre called the "plumule," which carries up with it a part of the seed called the "cotyledon," which (like a leaf) has the power of decomposing the carbonic acid of the air and fixing its carbon in the form of wood. This begins as soon as the cotyledon has reached the light, and thus the formation of fibres of woody matter takes place, which fibres descend from the cotyledon to the radicle. Meanwhile the formation of other cells of the plumule takes place, until the first leaf is formed, when other fibres of wood are sent down, and so on for every leaf, so that the number of woody fibres which form the trunk of a tree is in proportion to the number of leaves which that tree has borne, from which we come to the conclusion that the size of the trunk of a tree is the sum of all its branches. While all this is going on, the cellular tissue of the downward part or radicle also becomes developed and divides out into roots, on the surface and at the extremities of which are minute cellular bodies called "spongioles" (from their power of absorbing moisture), which take up the fluid of the earth which surrounds them; this moisture ascends through the vessels of the plant till it arrives at the surface of the leaves, where it is exposed to the action of light and sunshine. The ascent of the moisture of the earth was first correctly explained by Du Trochet, and is owing to a peculiar power which he discovered, and which is called "Endosmose;" this consists in the tendency which a fluid has to penetrate a membrane on the other side of which is a fluid of greater density than itself. This may be seen by the following experiment: obtain a piece of glass tubing about a foot long, having the end blown out into the form of a bell, as in fig. 7, tie a piece of bladder over the expanded end and fill it partly with syrup or gum-water, so that this shall rise in the stalk about an inch; place this in a glass of water with the bladder downwards, and the fluid will be seen slowly to rise in the stalk, so that in perhaps an hour it will rise to the top. This apparatus resembles one of the spongioles at the extremity of the fibre of a root.