Chapter VII: Part 7

The coasts which surround the Caribbean Sea and the Gulf of Mexico, and also the Atlantic shores of North America from the point of Florida to the mouth of the Chesapeake, are bordered by a very large number of marine marshes, forming a continued series over hundreds and thousands of miles in length. In this immense series of coast-marshes all kinds of vegetation seem to flourish, and threaten to get the better of the mud and water, and to convert them into _terra firma_. To the south, upon the shores of Colombia and Central America, the mangroves and other trees of like species plunge the terminal points of their aerial roots deep into the mud, crossing and recrossing in an arch-like form, and retaining all the débris of plants and animals under the inextricable network of their natural scaffoldings. The shores of the Gulf of Mexico, in Louisiana, Georgia, and Florida, are bordered by cypress swamps, or forests of cypress (_Cupressus disticha_); these strange trees, the roots of which, entirely buried, throw out above the layer of water which covers the soil multitudes of little cones, the business of which is to absorb the air. For millions of acres nearly all the marshy belt along the seashore is nothing but an immense cypress swamp, with trees bare of leaves, and fluttering in the wind their long hair-like fibres of moss. Here and there the trees and muddy soil give place to bays, lakes, or quaking-meadows, formed by a carpet of grass lying upon a soil of wet mud, or even upon the hidden water. In Brazil these buoyant beds of vegetation are frequently met with, and the significant name of _tremendal_ has been given to them: in Ireland these are called “quaking-bogs.” The least movement of the traveler who ventures upon them makes the soil tremble to some yards’ distance.

To the north of Florida, in the Carolinas and Virginia, the belt of cypress swamps continues; but in consequence of the change of climate and vegetation, the quaking-meadows are gradually converted into peat-mosses. The surface of the marsh is incessantly renewed by a carpet of green vegetation, while below, the dead plants, deprived of air, carbonize slowly in the moisture which surrounds them: these are the beds of peat which form upon the ground just as the layers of coal were formed in previous geological epochs.

On the southern side, the first great peat-bog of a well-defined character is the “Dismal Swamp,” which extends along the frontiers of North Carolina and Virginia. This spongy mass of vegetation rises ten feet above the surrounding land. In the centre, and, so to speak, upon the summit of the marsh, lies Lake Drummond, the clear water of which is colored reddish-brown by the tannin of the plants. A canal, which crosses the Dismal Swamp to connect it with the adjacent streams, is obliged to make its way along the marsh by means of locks. To the north of Virginia peat-bogs proper become more and more numerous; and in Canada, Labrador, etc., they cover vast expanses of country. All the interior of the island of Newfoundland, inside the inclosure formed by the forests on the shore, is nothing but a labyrinth--a great part of which is still unknown--of lakes and peat-bogs; even on the sides of the hills there are marshes on so steep an incline that the water from them would disappear and run off in a stream if it was not stopped by the thick carpet of plants which it saturates. Many a large peat-bog which may be crossed dry-shod contains more water than many lakes filling a hollow of the valley with deep water.

Opposite Newfoundland, on the other side of the Atlantic, Ireland is hardly less remarkable for the enormous development of its peat-mosses or bogs. These tracts of saturated vegetation, in which _Sphagnum palustre_ predominates, comprehend nearly two and a half millions of acres--the seventh part of the whole island. The inhabitants continue to extract from them, every year, immense quantities of fuel. The spaces left by the spade in the vegetable mass are gradually filled up again by new layers. After a certain number of years, which vary according to the abundance of rain, the depth of the bed of water, the force of vegetation, and the slope of the soil, the turf “quarry” is formed anew. In Ireland it generally takes about ten years to entirely fill up again the trenches, measuring from nine to thirteen feet in depth, which are made in the bogs on the plains, when a fresh digging of turf may be commenced. In Holland, crops of this fuel may be gathered, on an average, every thirty years. In other peat-moss districts the period of regeneration last forty, fifty, and even a hundred years. In France, on the borders of the Seugne (Charente-Inférieure), it has been ascertained that ditches five feet deep and nearly seven feet wide are completely obstructed by vegetation after the lapse of twenty years. As for the beds of peat which carpet the sides of mountains, they take centuries to form afresh.

In Ireland, the Low Countries, the north of Germany and Russia, heaps of trunks of former forest-trees--oaks, beech, alder, and other trees--are frequently discovered, which by their decay have made way for the peat-mosses. The _Sphagnum_, too, often takes possession of ground of which man had previously made himself master, and in many places roads, remains of buildings, and other vestiges of human labor are found below the modern bed of vegetation by which they are now covered. Certain peat-bogs in Denmark and Sweden may be considered, on account of the curiosities which have been found in them, as perfect natural museums, in which the relics of the civilization of ancient nations have been preserved for the _savants_ of our own day.

The air above the peat-mosses of Ireland and other countries in the world is not often unhealthy, either because the heat is not sufficient to develop miasma, or else because the vegetation, by absorbing the water into its spongy mass, impedes the corruption of the liquid, and produces a considerable quantity of oxygen. Further south, the peat-mosses, which are intermixed with pools of stagnant water, and especially marshes properly so-called, generate an impure air, which spreads fever and death over the surrounding country. Unless marshes are surrounded with dense forests, which arrest the dispersion of the gases, the latter exercise a most injurious influence on the general salubrity of the district; for during dry weather, a vast area of the bed of the marshes becomes exposed, and the heaps of organic débris lying on the bottom decompose in the heat and infect the whole atmosphere. The average of life is much shorter in all marshy countries than in the adjacent regions which are invigorated by running water. In Brescia, Poland, in the marshes of Tuscany, and in the Roman plains, the wan and livid complexion of the inhabitants, their hollow eyes, and their feverish skin, announce at first sight the vicinity of some centre of infection. There are some marshes in the torrid zone where the decomposition of organic remains goes on with a much greater rapidity than in temperate climates; no one can venture on the edges of these districts without peril to his life. As Frœbel ascertained in his journey across Central America, the miasma is occasionally produced in such abundance that not only can it be smelt, but a distinct impression of it is left upon the palate.

LOWLAND PLAINS
--WILLIAM HUGHES

The plateaus and mountain regions of the globe occupy a large portion of its surface--perhaps more than half of the whole extent of the land--and their influence over its climate and other natural conditions affecting mankind is very great. The highlands of the Old World--fitted by their physical attributes to be the home of pastoral and nomad races--were among the regions earliest occupied by mankind. From the banks of the Euphrates and the primeval cities of the Assyrian plain, the course of the shepherd-warrior--whether directed to the east or the west--led toward some of the elevated regions which stretched thence within the same (or nearly the same) degrees of latitude, and which, at least in a general sense, are under like conditions of climate. The highlands of Persia and Afghanistan, in the one direction, of Syria and the Lesser Asia, in the other, display abundant evidence, both in traditional and monumental records, of their early occupation by man. From the one, the natural order of advance leads to the fertile plains of India; from the other, to the shores of the Mediterranean, whence is easy transit to the peninsula and islands that lie beyond.

But if the highlands of the earth were early the dwelling-place of the shepherd-warrior, it was within the adjoining lowland plains and fertile river basins that the arts of civilization were first called into being, that towns were built, that population became numerous, and that systems of social polity were developed. The lowland plains of Asia and Europe constitute, in the present day, the most populous regions of the globe, and include by far the more numerous portion of the human race. The like regions in the New World are fast filling with inhabitants, as the redundant population of older lands is directed, in an ever-flowing stream, across the waters of the Atlantic.

The most important and extensive among the lowland plains of the Old World are the following:

IN ASIA.--Plain of the Euphrates and Tigris (the ancient Mesopotamia and Babylonia); Plain of Hindustan, or Northern India; Plain of China, embracing the northeast part of that country; Plain of Siberia; Plain of Turkestan. Among lowland regions of less importance are the plains of Pegu, Siam, and Tonquin, all within the Indo-Chinese peninsula, or India beyond the Ganges.

IN EUROPE.--The Great Eastern Plain, embracing nearly the whole of Russia; Plain of Hungary, embracing the middle portion of the valley of the Danube; Plain of Wallachia and Bulgaria, or the Lower Danube; Plain of Lombardy, or Northern Italy; Plain of Languedoc, in the south of France; Plain of Andalusia, in the south of Spain; Plain of Bohemia, or basin of the Upper Elbe.

The limits and direction of these regions may be traced upon any ordinary map, by means of their coincidence with the great river basins of the Eastern Hemisphere. They include the longer slopes of the land, which are directed toward the north and northwest, as well as the less extensive low grounds which border the Indian and Pacific Oceans. The Siberian plain alone comprehends an area equal to that of Europe, and the rivers by which it is watered are among the most considerable in the Old World. So vast an area, under other conditions of climate, might have become the home of populous nations, the seat of civilization and empire. But its high latitudes, which involve the rigor of an Arctic sky, condemn a large portion of Siberia to the condition of a sterile wilderness, and must prevent even its more favored districts from being other than thinly inhabited. The dreary swamps and morasses of the _tundras_, which replace, during the brief summer of those latitudes, the plain of ice and snow, stretch along the shores of the Arctic Sea through a vast extent of this widespread region.

Conditions hardly more favorable belong to the extreme northern portion of the great plain of Europe, the slope of which is directed toward the White Sea and the Arctic basin. But a large portion of Eastern Europe is inclined toward a southerly sky, and is watered by rivers which have their outfall into the Black and Caspian Seas. The Volga, the longest of European rivers, belongs to the Caspian basin, the most depressed portion of the entire region.

The southeastern division of the European lowland, and the adjacent portions of Asia, constitute the region of the _steppes_. These occupy an immense portion of the empire of Russia, and are among the most characteristic of the physical features of the Old World. The steppes are grassy plains--prairies, or meadows, they would be called in the New World--which occupy a vast belt of the European and Asiatic continents. They stretch eastward from the banks of the Dnieper far into the heart of Asia--along the shores of the Caspian and Aral Seas, and as far as the banks of the great river Obi. Indeed, in so far as their grassy covering and general level expanse--among the prime characteristics of the steppe-land--are concerned, a like region may be said to extend to the eastward through Central Asia, as far as the Great Wall of China and the valley of the Amour. This is the “land of grass” of the Mongol shepherd, the true home of the Tartar nations, whose descendants yet preserve in their songs the memory of their famous leader Timour--the Tamerlane of historic record. So vast is the extent of this grass-covered region, that a mounted horseman, it has been said, setting out from one of its extremities at the beginning of the year, and traveling day and night at his utmost speed, would find the season of spring elapse ere he reached its further limits.

The southwestern portion only of the steppe-land falls within the limits of Europe. This exhibits an unbroken expanse of level plain--fatiguing to the eye from its perfect uniformity--dry and burned up by excessive heat in summer, a pathless expanse of snow during the opposite season of the year. The steppe is only productive during the brief time that the thirsty soil is refreshed by the rains of spring and early summer. Its aspect is then, for a time, glowing and verdant; grass and wild flowers cover the earth with a carpet of varied and attractive hues, and the wild cattle and horses luxuriate in the abundant pasture. In the autumn, when the herbage has become dry and withered, the steppe sometimes exhibits a vast sheet of rolling flame, the grass being occasionally fired by accident, at other times intentionally, for the sake of the young crop which springs up through the ashes. The illusive phenomena of _mirage_--the result of atmospheric refraction, engendered by the intense dryness of the air--are of frequent occurrence in the steppe. Sometimes the eye is cheated by the semblage of a lake, which vanishes on approach. In other instances, the traveler over these wild regions appears to see rising before him, and glittering through the dense mist which often prevails during the hours of midday heat, the towers and other buildings of a distant city. Spires, trees, bridges, rivers, all appear in picturesque combination, only to sink into confusion as they are approached. When the spot where the city of enchantment had seemed to stand is actually reached, there is found only the long, dry grass, waving as elsewhere in the surrounding waste. The vast accumulation of dry sand on the surface gives rise to another phenomenon, of frequent occurrence on the steppe, resembling waterspouts upon the sea, excepting that the column is filled with dust instead of water. “Suppose the great flat steppe stretched out beneath the blue sky--nothing visible--no breath of air apparently stirring--the whole plain an embodiment of sultriness, silence, and calmness--when gradually rise in the distance six or eight columns of dust, like inverted cones, two or three hundred feet high, gliding and gliding along the plain in solemn company; they approach, they pass, and vanish again in the distance, like huge genii on some preternatural errand.”

Such is the region over which the semi-nomad tribes of Tartar shepherds, who constitute a fraction of the vast population of the Russian Empire, pasture their herds. It is only here, within the limits of Europe, that the camel is successfully reared. Odessa, the great outport of southern Russia, stands almost on the edge of the steppe, and the whirlwinds of dust that pass through its streets, and constitute, during a portion of the year, one of its chief drawbacks as a place of residence, furnish obvious evidence of this proximity. The steppe includes two-thirds of the Crimean peninsula, the extreme south of which, however, is traversed by a hill-range of considerable elevation, and exhibits widely different features.

Beyond the Dnieper, the Don, and even the Volga, the same region of alternate grassy plain and sandy waste stretches far into the Asiatic continent. To the east and north of the Caspian and the Aral are the steppes over which roam the hordes of the Khirghiz. The names of Kara-kum and Kizil-kum, given respectively to the sandy wastes which extend upon either side of the river Syr, or Jaxartes, are strikingly indicative of the general character of the tracts to which they are applied.

Mr. T. W. Atkinson, in his _Travels in Regions on the Upper and Lower Amour_, thus describes the journey through these wild regions: “For many miles the sand was hard, like a floor, over which we pushed on at a rapid pace. After this we found it soft in places, and raised into thousands of little mounds by the wind. Our horses were now changed, and in an hour these mounds were passed, when we were again on a good surface, riding hard.... Hour after hour went by, and our steeds had been changed a second time.... In our route there was no change visible--it was still the same plain; there was not so much as a cloud floating in the air, that, by casting a shadow over the steppe, could give a slight variation to the scene.... The whole horizon was swept with my glass, but neither man, animal, nor bird could be seen.... We rode on for several hours, but there was no change of scene. One spot was so like another that we seemed to make no progress.... No landmark was visible, no rock protruded through the sterile soil; neither thorny shrub nor flowering plant appeared, to indicate the approach to a habitable region; all around was ‘kizil-kum’ (_red sand_).”

The perfect solitude and unbroken silence of the desert are not less characteristic than its wearisome monotony of surface. No sound of bird or animal breaks the solemn stillness which reigns around; no trees expose their foliage to the influence of the wind. The course of the traveler is still onward, through the same apparently interminable waste. “Fourteen hours had passed, and still a desert was before us. The sun was just sinking below the horizon. The Kirghiz assured me that two hours more would take us to pastures and to water.... It had now become quite dark, and the stars were shining brilliantly in the deep blue vault. My guides altered their course, going more to the south. On inquiring why they made this change, one of them pointed to a star, intimating that by that they must direct their course.

“We traveled onward, sometimes glancing at the planets above, and then anxiously scanning the gloom around, in the hope of discovering the fire of some dwelling that would furnish food and water for our animals. Having ridden on in this manner for many miles, one of our men stopped suddenly, sprang from his horse, and discovered that we had reached vegetation. The horses became more lively and increased their speed, by which the Kirghiz knew that water was not far off. In less than half an hour they plunged with us into a stream, and eagerly began to quench their terrible thirst, after their long and toilsome journey.”

The features above described are those of the steppe region, regarded as a whole. But this aspect undergoes considerable variation in particular localities. The Lower Steppes, as those portions of the great plains which immediately border the Caspian are termed, exhibit a soil largely impregnated with saline particles, and contain numerous salt-water lakes. Some of these lakes furnish a large quantity of salt, derived by means of evaporation. This region resembles in aspect the dried-up bed of a sea. The Caspian, upon which it borders, occupies the lowest part of a depression below the general level of the earth’s surface, its waters being 81 feet lower than those of the Black Sea. The extent of the Caspian appears to be gradually diminishing.

The features of the steppe-land, however, are exceptional to the general characteristics of the European plain, regarded as a whole. Large portions of its middle and western divisions possess a rich arable soil, and exhibit annually a waving sea of corn. The geographical limits of the lowland region are marked, in the direction of north and south, by the Black Sea and the Arctic Ocean. The eastwardly portions of this vast level expanse stretch into the heart of Asia. In the west it reaches the shores of the Baltic, and is thence prolonged, with narrower dimensions, through northern Germany and the low flats of Holland, until it subsides beneath the water of the German Ocean. Throughout this vast extent, tertiary and recent formations prevail, and the abundant clays, sands, and gravels give their character to the surface-soil. The plain lying to the south of the Baltic consists principally of sandy heaths, and contains, toward the seashore, a vast number of small lakes or _meers_.

The low shores of Holland--conquered from the sea by the persevering industry of the Dutch nation--furnish a conspicuous example of the sand-hills, or _dunes_, which are often found on low sandy coasts, and which owe their origin to the action of prevailing winds upon the loose drift-sand. Where no means are adopted to fix them to the soil, the sand-hills become agents of destruction, sometimes overwhelming whole villages in their slow but steady advance inland. But this is not the case in Holland, where the ingenuity of the Dutch has converted them from instruments of destruction into a means of national preservation. In some of the provinces of the Netherlands, a large portion of the land is actually lower than the level of high-water mark, and is therefore exposed (it might appear) to the ravages of the adjoining ocean. But from the channel of the Helder southward, the coast is protected by a line of broad dunes, or sand-hills, which are partially covered with grass or heath, and are in some places from forty to fifty feet in height. These have been formed by the natural process above adverted to, and still in operation; the prevalent sea-winds raise banks or ridges of sand at a short distance from the coast, which the inhabitants prevent from proceeding further inland by sowing them with a kind of grass (_arundo arenaria_), the long roots of which bind the whole mass firmly together.

The district of the _Landes_, in the southwest corner of France, offers an example of the combined action of sand and sea which is widely different from the above in its results. The coast here exhibits a line of shifting sand, backed toward the interior by a belt of pine-forest. For a length of nearly two hundred miles, from the mouth of the Garonne to that of the Adour, there stretches along the extreme edge of the sea a range of hills composed of white sand, as fine as though it had been sifted for an hour-glass. Every gale changes the shape of these rolling masses of drift-sand. A strong wind from the land flings millions of tons of sand per hour into the sea, to be again washed up by the surf, flung upon the beach, and with the first Biscay gale blown in whirlwinds inland. A water hurricane from the west has been known to fill up with sand many square miles of shallow lake, driving the displaced waters inland, dispersing them among the pine-woods, flooding and frequently destroying the scattered hamlets of the people, and burying forever their fields of millet and rye. The shepherds of the Landes pursue their avocation mounted upon stilts, which raise them above the reach of the sand-blasts. The pine-forests yield annually a large supply of resin, the only harvest of this wild region. Intermixed with the pine-forests, a chain of shallow and marshy lakes stretches in a direction parallel to the coast, and at a few miles inland.

This Reef is composed entirely of Stag’s Horn Coral (_Madrepora Hebes_)]

The lowland plains of the New World are on a scale of vast magnitude, and, if not superior in extent to those of the Eastern Hemisphere, yet bear a much larger proportion to the entire area of the land. They are watered, moreover, by the longest rivers of the globe, and enjoy, for the most part, conditions of situation and climate in the highest degree favorable to man. Both in North and South America, the whole central expanse of the continent exhibits a vast succession of lowland plains, the only division between the different portions of which is that formed by the watersheds of its longer rivers--not always to be traced without difficulty, owing to the generally level nature of the entire plain. In North America, the prairies; in South America, the tracts known as llanos, selvas, and pampas, are included within the lowland region, and exhibit some of the most characteristic among the aspects of nature in the Western world.

The prairies coincide, in a general sense, with the middle and upper portion of the Mississippi Valley, embracing the vast region which extends from the Great Lakes to the base of the Rocky Mountains. They are covered in their natural state with a rich herbage, and exhibit a waving sea of grass several feet high. At intervals, toward the banks of the rivers, patches of forest vegetation break the uniformity of the prospect, but the prairie itself is destitute of trees, and (as the name implies) is merely a grassy plain, or meadow. Alternate forest and prairie constitute the great features of natural scenery in the New World. When the rich soil of the prairie-land is broken up by the plow--an operation which is rapidly progressing, year by year, within the Western States of America--it yields abundant crops of corn. There are, however, within the vast extent of the North American continent, immense regions which yet retain the aspect of the wilderness. It was within these regions that the buffalo roamed, in vast herds, and that the native Indian hunter pursued his game ere the advancing footsteps of the white man had driven him from his haunts.

The llanos, or savannahs, are vast grassy plains, which occupy nearly the whole basin of the Orinoco River, excepting only toward its highest portion, when they are succeeded by wooded plains. The llanos resemble in general features the prairies of the Mississippi Valley, but have for the most part a lower level, and (owing to the abundant rains of the torrid zone) are annually inundated by the rivers to an immense extent. Whole districts, embracing thousands of square miles, are annually converted, within the interior plains of South America, into lakes, or temporary seas of fresh water, to be rapidly evaporated under the burning rays of a vertical sun. At the close of the rainy season the llanos are covered with grass, and form rich natural pasture-grounds. During the prolonged season of drought which ensues, the verdure is entirely destroyed, and the parched earth opens in wide and deep crevices--again to be laid under water with the recommencement of the rains.

The selvas, or forest-plains, belong to the valley of the Amazon, and include an immense area of Brazil, watered by the lower portion of the great stream and its chief tributary, the Madera. Vast regions are here covered by an uninterrupted forest, composed of trees of giant growth, their boughs interlaced by immense creeping plants, and the ground beneath thickly covered with a dense growth of underwood. To the southward of the forest region are vast grassy plains, which stretch in that direction into the valley of the Paraguay.

The pampas, or plains of the Paraguay and Paraná valleys, exhibit the same luxuriant natural growth of herbaceous plants as other lowland regions of the New World. They include an immense region, which stretches from the neighborhood of the southern tropic far to the southward of the river Negro (lat. 39° S.), and from the banks of the Paraná to the eastern base of the Andes. The pampas are variously covered with long coarse grass, mixed with wild oats, clover, and other herbage. The tract of country known by the name of El Gran Chaco, immediately to the westward of the upper Paraguay--scarcely tenanted excepting by wild beasts--exhibits a luxuriant covering of grass, which springs from a soil possessed of the highest natural capabilities.

Further south, the plains that extend from Buenos Ayres to the foot of the Andes are covered, during a great part of the year, with gigantic thistles, which grow to the height of seven or eight feet, and are so thick as to render the country almost impassable. For nine months of the year the thistles are here the predominant (and almost the sole) feature of the vegetable kingdom; but with the heats of summer they are burned up, and their tall leafless stems are leveled to the ground by the powerful blast of the pampero, or southwest wind, which blows from the snowy ranges of the Andes, after which the ground is covered for a brief season with herbage. This is destined, with the returning spring, again to give place to the stronger vegetation which it had succeeded, and for a time supplanted.

THE SMELL OF EARTH
--G. CLARKE NUTTALL

A bright fine evening after a day of rain is one of Nature’s compensations. The air is peculiarly sweet and fresh, as though the rain had washed all evil out of it. The mind, relieved from the depressing influence of continuous rain, is exhilarated, and, above all, the strong smell of the earth rises up with a scent more pleasing than many a fragrant essence. In the town, indeed, this earthy smell is often obscured by the bricks and mortar which cover the land, and by the stronger, less wholesome, odors of human life, but in the country it has full sway, and fills the whole air with its presence. Even a slight shower, particularly after drought, is sufficient to bring out the sweet familiar smell of the land and thrust it upon our notice.

The smell of freshly turned earth is often regarded by country lovers as one of the panaceas for the ills of the flesh, and “follow a plowshare and you will find health at its tail” has proved a sound piece of advice to many a weakly town-sick one, over whose head the threatenings of consumption hung like the sword of Damocles, though it is possible that it is the fresh air, and more especially the sunshine, which are the saving media, and not the mere smell.

But what do we know about this characteristic smell of the soil? Can we regard it as the mere attribute of the soil as a simple substance, such an attribute as is, for instance, the peculiar smell of leather, or the odor of india-rubber; or can we go deeper and find that it is really an expression of complexity below?

Strangely enough this is the case, for the smell of damp earth is one of the latest sign-posts we have found which lead us into a world which, until recently, was altogether beyond our ken. It points us to the presence, in the ground beneath us, of large numbers of tiniest organisms, and not merely to their presence only, but to their activity and life, and reveals quite a new phase of this activity. A handful of loose earth picked up in a field by the hedgerow, or from a garden, no longer represents to us a mere conglomeration of particles of inorganic mineral matter, “simply that and nothing more”; we realize now that it is the home of myriads of the smallest possible members of the great kingdom of plants, who are, in particular, members of the fungus family in that kingdom, plants so excessively minute that their very existence was undreamed of until a few years ago.

Some faint idea of their relative size, and of the numbers in which they inhabit the earth, may be gleaned from the calculations of an Italian, Signor A. Magiora, who, a short time ago, made a study of the question. He took samples of earth from different places round about Turin and examined them carefully. In ordinary cultivated agricultural soil he found there would be eleven millions of these germs in the small quantity of a gramme, a quantity whose smallness will be appreciated when it is remembered that a thousand grammes only make up about two and a quarter pounds of our English measure. Thus, a shovelful of earth would be the home of a thousand times eleven millions of bacteria--but the finite mind can not grasp numbers of such magnitude. In soil taken from the street, and, therefore, presumably more infected with germs, he calculated that there was the incredible number of seventy-eight million bacteria to the gramme. Sandy soil is comparatively free from them, only about one thousand being discovered in the same amount taken from sandy dunes outside Turin.

But though the workers were hidden yet their works were known, for what they do is out of all proportion to what they are; in fact they perform the deeds of giants, not those of veriest dwarfs. “By their works shall ye know them” might be a fitting aphorism to describe the bacteria of the soil. And the nature of their deeds is widely various, for though the different groups are members of one great family, yet, like the individuals of a human family that is well organized, they have each of them their special vocation. In the spring time, when the sun warms the chilly earth, they act upon the husks that have protected the seeds against the rigors of the winter, and crumble them up so that the seedling is free to grow; they break down the stony wall of the cherry and plum which has hitherto imprisoned the embryo; and then, when the young plant starts, they attach themselves to its roots, assist it to take in all sorts of nutriment from air and soil, and thus help it in its fight through life, and when its course has run they decently bury it. They turn the green leaves and the woody stem and the dark root back into the very elements from which they were built up; they effect its decay and putrefaction, and resolve it into earth again. “Dust to dust, ashes to ashes,” is the great life work of the earth bacteria.

But up to about 1898 the fresh smell of the earth, the smell peculiar to it, had not been in any way associated with these energetic organisms, and it was quite a new revelation to find that it was a direct outcome of their activity. Among the many bacteria which inhabit the soil, a new one, hitherto unknown, has been isolated and watched. It lives, as is usual with them, massed into colonies, which have a chalky-white appearance, and as it develops and increases in numbers it manifests itself by the familiar smell of damp earth, hence the name that has been given it--_Cladothrix odorifera_. Taken singly, it is a colorless thread-like body, which increases numerically by continuous subdivisions into two in the direction of its length. It derives its nutriment from substances in the soil, which either are, or have been, touched by the subtle influence of life, and in the processes of growth and development it evolves from these materials a compound whose volatilizing gives the odor in question. This compound has not yet been fully examined; it is not named, nor have all its properties been satisfactorily elucidated, but two facts concerning it stand out clearly. One is that it is the true origin of the smell that we have hitherto attributed to earth simply; and the other, that it changes into vapor under the same conditions as water does. Therefore, when the sun, shining after the rain, draws up the water from the earth in vapor form, it draws up, too, the odorous atoms of this newly found compound, and these atoms, floating in the air, strike on our olfactory nerves, and it is then we exclaim so often, “How fresh the earth smells after the rain!”

Though moisture, to a certain extent, is a necessary condition of the active work of these bacteria, yet the chief reason why the earthy smell should be specially noticeable after the rain is probably because this compound has been accumulating in the soil during the wet period. We only smell substances when they are in vapor form, and since the compound under consideration has precisely the same properties in this respect as water, it will only assume gaseous form when the rain ceases. The bacteria have, however, been hard at work all the time, and when the sun shines and “drying” begins, then the accumulated stores commence their transformation into vapor, and the strong smell strikes upon our senses. For the same reason we notice a similar sort of smell, though in a lesser degree, from freshly turned earth. This is more moist than the earth at the surface, and hence, on exposing it, evaporation immediately begins which quickly makes itself known to us through our olfactory nerves.

It may also have been remarked that this particular odor is always stronger after a warm day than after a cold one, and is much more noticeable in summer than in winter. This is because moderate warmth is highly conducive to the greater increase of these organisms, and, in fact, in the summer they are present in far larger numbers and exhibit greater vitality than in the winter, when they are often more or less quiescent.

Two other characteristics of _Cladothrix odorifera_ are worthy of notice as showing the tenacity with which it clings to life. It is capable of withstanding extremely long periods of drought without injury; its development may be completely arrested (for water in some degree is a necessity with all living things, from highest to lowest), but its vitality remains latent, and with the advent of water comes back renewed activity. But besides drought it is pretty well proof against poisons. It can even withstand a fairly large dose of that most harmful poison to the vegetable world, corrosive sublimate. Hence any noxious matter introduced into the soil would harm it little ultimately; the utmost it could do would be to retard it for a time.

This, then, is the history of the smell of earth as scientists have declared it unto us, and its recital serves to further point the moral that the most obvious, the most commonplace things of everyday life--things that we have always taken simply for granted without question or interest--may yet have a story hidden beneath them. Like sign-posts in a foreign land, they may be speaking, though in a language not always comprehended by us, of most fascinating regions--regions we may altogether miss to our great loss if we neglect ignorantly the directions instead of learning to comprehend them.

DESERTS
--ÉLISÉE RECLUS

The most important group of deserts in the world is that of the Sahara, which extends across the African continent from the shores of the Atlantic to the valley of the Nile. This immense area is more than 3,100 miles from east to west, and is, on an average, more than 600 miles in breadth; it is, in fact, equal in size to two-thirds of Europe. In this region there is only one season, viz., summer, burning and merciless. It is but rarely that rain comes to refresh these regions, on which the solar rays dart vertically down.

The mean altitude of the Sahara is estimated at 2,000 feet; but the level of the soil varies singularly in the different districts. To the south of Algeria, the surface of the Chott Mel-R’ir, the remains of an ancient sea, which communicated with the Mediterranean, is at the present time more than 165 feet below the Gulf of Cabes; while to the south and east, the ground rises into plateaus and mountains of sandstone or granite to a height varying from 3,300 to 6,660 feet. In the centre of the Sahara stands the Djebel-Hogger, the sides of which are covered with snow during three months in the year; from December to March, its picturesque defiles are traversed by streams which flow some distance and lose themselves beneath the surrounding plains. This group of lofty mountains is the great landmark which forms the boundary between the eastern deserts, or the Sahara proper, and the group of western deserts, designated under the general name of Sahel.

The Sahel is very sandy. Throughout the greater part of its extent the soil is composed of gravel and large-grained sand, which does not give way even under the foot of the camel. Some of the ranges of sand-hills which rise in this desert are chains of small hills, composed of heavy sand which resists the influence of the wind. But in many districts of the Sahel, the arenaceous particles of the soil are fine and small. The trade-winds which pass over the desert distribute these sandy masses into long waves similar to those of the ocean, and here and there raise them into movable sand-hills, which overwhelm all the oases which lie across their path. Traveling toward the southwest, in which direction they are driven by the wind, the sands reach the northern shores of the Niger and Senegal at many points of their course, and by their incessant deposits gradually drive the waters of these rivers toward the south. To the west, the sand of the desert encroaches also upon the ocean. Off the coast which stretches between Cape Bojador and Cape Blanco--pointed out from afar by the highest dunes in the world--a line of sand-banks extends far out into the sea. A current of sand is, therefore, constantly passing across the desert from northeast to southwest. The débris of rocks in a state of decomposition, and the particles brought to the coast of the Gulf of Cabes by the tide, which is very powerful at this point, are driven before the wind into the plains of the Sahel, and thence, after a journey lasting hundreds and perhaps thousands of years, they at last reach the seashore of the Atlantic, in order to recommence in the oceanic currents another eventful odyssey.

Some parts of the eastern Sahara are equally sandy; but the principal parts of the surface of this desert are occupied by plateaus of rock or clay, and by groups of grayish or yellowish mountains. The chains of sand-hills are numerous, and, like those of the west, they travel incessantly under the impulse of the wind in a south or southwest direction. The rocky plateaus are crossed and recrossed here and there by wide and deep clefts, which are gradually filled by the drifted sand, and into which the traveler runs the risk of sinking, like the mountaineer into the _crevasses_ of a glacier. In the hollows, patches of salt take the place of the lakes which in more rainy countries would be found there.

Those districts of the Sahara which are destitute of oases present a truly formidable aspect, and are fearful places to travel over. The path which the feet of the camels have marked out in the immense solitude points in a straight line toward the spot which the caravan wishes to reach. Sometimes these faint footmarks are again covered with sand, and the travelers are obliged to consult the compass, or examine the horizon; a distant sand-hill, a bush, a heap of camels’ bones, or some other indications which the practiced eye of the Touareg alone can understand, are the means by which the road is recognized.

Terrible stories are told by the side of the watch-fires of caravans being overtaken when amid the sand-hills by a sudden storm of wind, and completely buried under the moving masses; they also tell of whole companies losing their way in the deserts of sand or rocks, and dying of madness after having undergone all the direst tortures of heat and thirst. Happily such adventures are rare, even if the accounts of them are at all authentic. Caravans, when led by an experienced guide and protected by treaties and tribute against the attacks of plundering Arabs and Berbers, nearly always arrive at the end of their journey without having undergone any other sufferings than those caused by the intolerable heat, the want of good water, and the coldness of the nights; for the nights which follow the burning days in the Sahara are in general very cold. In fact, the air of these countries being entirely destitute of aqueous vapor, the heat collected during the day on the surface of the desert is, owing to the nocturnal radiation, again lost in space. The sensation of cold produced by this waste of heat is most acute, and especially so to the chilly Arab. Not a year passes without ice forming on the ground, and white frosts are frequent.

In all those countries in the Sahara where the water gushes out in springs or descends in streams from some group of mountains, there is an oasis formed--a little green island, the beauty of which contrasts most strikingly with the barrenness of the surrounding sands. These oases, compared by Strabo to the spots dotted over the skin of the panther, are very numerous, and perhaps comprehend altogether an area equal in extent to one-third of the whole Sahara. In the greater part of this region, the oases, far from being scattered about irregularly, are, on the contrary, arranged in long lines in the middle of the desert. The cause of this is either the higher proportion of moisture contained in the aerial currents which pass in this direction, or, and perhaps principally, the subterranean water which follows this slope, and here and there rises to the surface.

The oases are, _par excellence_, the country of date-trees; in the neighborhood of Mourzouk there are no less than thirty-seven varieties. These trees form the riches of the tribe, for their fruit supplies food to man as well as to beast--to dromedaries, horses, and dogs. Below the wide fan of leaves, which quiver in the blue air, are thickly growing clumps of apricot, peach, pomegranate, and orange trees, their branches loaded with fruit, and vines intertwining round the trunks; maize, wheat, and barley ripen under the shade of this forest of fruit-trees, and, lower still, the modest trefoil fills up the very smallest intervals of the soil which is capable of irrigation.

To the east of Egypt, which may be considered as a long oasis situated on the banks of the Nile, the desert begins again, and borders the whole extent of the Red Sea. A large part of Arabia presents nothing but sands and rocks, and toward the southeast, in the Dahna, there are solitudes which no traveler, either Arab or Frank, seems yet to have crossed. To the north and east stretch the _Nefouds_, or “daughters of the great desert,” which are much smaller than the Dahna, but are nevertheless formidable tracts to travel over. One of these regions, which was crossed by Palgrave, is that in which the mass of sand, formerly deposited there by the marine currents, affords the greatest depth; in certain places it is 330, 400, and even 500 feet deep. It can be measured by the eye by descending to the bottom of the funnel-shaped cavities, which the springs of water, spouting out of the adjacent granite or calcareous rock, have gradually hollowed out in the bed of sand. This enormous bed of material, which represents chains of pulverized mountains, does not exhibit an even surface, as one would expect, but, throughout its whole expanse, presents long symmetrical undulations, similar to those waves which roll in the Caribbean Sea under the even influence of the trade-winds. These waves stretch from north to south, parallel to the meridian; it is probable that they are owing to the movement of the earth round its axis. The solid rocks beneath unresistingly obey the impelling force which carries them toward the east, but the movable sands which are above them do not allow themselves to be carried away with an equal rapidity; each day an infinitesimal quantity remains behind and seems to glide toward the west, like the waves of the ocean, the atmospheric currents, and everything that is movable on the face of the globe. The parallel furrows of sand in the Nefouds certainly rise to a greater height than those of the other deserts, and differ much in their aspect from the smaller waves of sand formed by the wind; but the reason is, that the bed of sand in this region is of a very great bulk, and because at this point the swiftness of the globe nearly attains its maximum on account of its vicinity to the equator.

To the east of the Arabian peninsula, the chain of deserts is prolonged obliquely across Asia. The principal part of the plateau of Iran, occupying a quadrilateral space, surrounded by mountains which stop the rains in their passage, consists of sterile solitudes, some covered with saline beds, the remains of dried-up lakes, others spread over with shifting sands, which the wind blows up into eddies, or dotted over with reddish-colored hills, which the mirage renders either nearer or more distant to the eye than they really are, incessantly modifying them according to the undulations of the atmosphere. This plateau is only separated from the steppes of Turkestan by the Elburz Mountains, and is continued toward the east by the deserts of Afghanistan and Beloochistan, which are not so large, and much easier to travel over. Even the rich peninsula of India is protected by a belt of sterile tracts situated on the right and left of the Indus. Between each of the five rivers (Punjaub), which, by the union of their waters, form the great river, stretches a line of steppes in which the torrent-waters of the mountains are soon lost. The soil of these steppes is nearly everywhere barren, except on the edge of the irrigation canals constructed by the inhabitants at a very heavy outlay.

Beyond the mighty central group, whence radiate far and wide the mountain-chains of Asia, the steppes and deserts, mutually alternating according to the topographical conditions, and the abundance or scarcity of water, extend over a space of more than 1,850 miles between Siberia and China Proper. The eastern part of this belt is called, according to the languages, Gobi or Chamo, that is to say, the desert _par excellence_, and, from its enormous dimensions, corresponds with the Sahara of Africa, situated exactly at the opposite extremity of the long chain of solitudes which stretches right across the Old World. The mirage, the moving sand-hills blown up into eddies, and many other phenomena described by African travelers, are found in certain districts of the Gobi, just the same as in all other deserts. But the cold here is exceptionally intense, on account of the great height of the plateaus, which is on an average 4,950 feet, and the vicinity of the plains of Siberia, which are crossed by the polar wind. It freezes nearly every night, and often during the day. The dryness of the atmosphere is extreme; there is hardly any vegetation, and a few grassy hollows are the only oases of these regions. From Kiahkta to Pekin, there are only five trees for a distance of 400 to 500 miles, which is the width of the desert in this part of Mongolia. The Gobi, however, like the Sahara, was formerly covered by the waters of the ocean; even on the elevated plateaus, old cliffs may be noticed, the bases of which are worn away by the waves, and long strands of round shingle stretch around the area which was formerly occupied by a now vanished gulf.

In North, as in South America, the deserts proper lie to the west of the continent, and occupy the basins commanded by the parallel or divergent walls of the Rocky Mountains.

The most northerly of these American deserts occupies, to the west of Lake Utah, a part of the space called the “Great Basin,” and is comprised between the principal chain of the Rocky Mountains and the Sierra Nevada of California. The desert of Utah is an immense surface of clay, dotted over with thin tufts of artemisia; in certain places, however, it exhibits no trace of vegetation, and resembles a causeway of concrete, intersected by innumerable clefts, forming nearly regular polygons. In the midst of these solitudes no rivulet flows, and no water-spring gushes forth; only after journeying for many a long hour the traveler sometimes comes upon some field of crystallized salt, a white expanse, on which the clouds and blue sky are reflected as on the surface of a lake. On the extreme horizon some volcanic rocks may be seen, like great scoriæ, half veiled by warm atmospheric columns, quivering like the air over the flame of a hot brazier. Across these vast plains, inhabited only by a prodigious quantity of extraordinarily shaped lizards, the road employed by the emigrants used to pass, which was so soon destined to be supplanted by the Pacific Railway from New York to San Francisco.