It is very important to remember that the soil is a sort of last home to which the particles of carbon, of nitrate, and minerals always return after their wanderings in the bodies of plants, of insects, or of other animals. They probably rest but a short time before they again set off on new adventures.

One might say the same of the water, and of the carbonic acid gas and oxygen of the atmosphere, for the water, falling as rain upon the earth, trickles down to the underground water-level. Then it immediately begins to rise up between the particles of earth and is promptly caught and sucked in by the roots, only to be again given out by their leaves. The carbonic acid gas and oxygen also are always entering and leaving the foliage. Even the nitrogen of the air is not left alone in the atmosphere. There are small germs in the soil which are able to get hold of it and make it into valuable nitrates.

More curious still is the fact that electric charges can be used to change the comparatively useless air-nitrogen into useful manures. Probably the farmer will some day make his own nitrates by electricity.

The structure of the soil or earth is a most interesting and romantic part of botany. It is true that a "radical" disposition is necessary if one is to go to the root of the matter, but, unless we do this, it is impossible to realize the romance of roots.

Down below is the unaltered rock, sand, or clay. Next above it comes the subsoil, which consists of fragments of the rock below, or of sand, clay, etc., more or less altered by deep-going roots. Even in this subsoil, bacteria or germs may be at work, and the burrows of worms and insects often extend to it. Next above the subsoil comes the true soil; there is plenty of the stones, soil, sand, or whatever it may be that constitutes the subsoil, but its richness consists in its contents of valuable minerals, and especially of broken-up leaves, corpses of insects, and manure. Above this true soil are first the leaf-mould of two years ago, then that of the year before last, and on the top is the leaf-mould and other decayed products of last winter.

All these upper layers are full of life and activity, which probably goes on vigorously all the year round.

The population of worms is especially important. The worm is a voracious and gluttonous creature: it is for ever swallowing bits of leaves and rich soil. Inside its body there are lime-glands which act upon the vegetable food and improve its quality as manure. The worm comes up to the surface at night or early morning and leaves the worm-casts upon it. The rain then washes the rich, finely-divided matter of the casts down into the soil again. It is said that there are about 160,000 worms at work in an acre of good soil. Yet their life is full of danger. A keen-eyed population of blackbirds, thrushes, starlings, peewits (plover), and partridges are always watching for and preying upon the poor worm. Even in his burrows, which may be six feet deep, he is not safe, for the mole (moudiewarp) is also both very hungry and very active, and delights in eating him.

In the soil also and even deeper in the subsoil are many insects; some hibernate in the winter, and at other times actively gnaw the roots of plants or devour dead leaves and twigs (see Chapter xxiii.). Thus there are many burrows and holes, so that there is no want of air in the soil, which is indeed necessary both for these creatures and also for the roots of the plants.

Rain comes down through the soil, carrying with it carbonic acid, mineral salts, and also germs or bacteria, which form perhaps the most important population of all.

No work could be carried on without their help; it is bacteria which, at every stage of decay, assist in breaking up leaves, twigs, insects' bodies, worm-casts, and other manures. The way in which they work is too difficult to explain here, but to get an idea of the romance of the underground world one must try to picture to oneself these swarms and myriads of germs and bacteria all incessantly and busily engaged at their several duties. In the uppermost layers there are probably in a single cubic inch of good soil from 54,000,000 to 400,000,000 of these microbes. Many are absolutely necessary to the harvest; a few may be of little importance, but there are sure to be some of those dangerous sorts which might devastate a continent with disease in a single summer.

There are also quantities of other fungi. The fairy rings which one sees year after year in widening circles of bright, fresh green are the work, not of fairy footsteps, but of an underground fungus (Marasmius oreades and others). Its threads are thin, white, and delicate; they attack the roots of grasses, etc., on the outer side of the ring. It is therefore on this outer side yellow, dry, and more or less withered. On the inner side, however, the grass is luxuriant and of a rich bright green. Here the fungus has died off, and its remains, as well as those of the plants which it destroyed, form a rich manure for the new grass following on its track. Every year the ring widens; at a certain time in summer one sees the irregular line of mushroom-like fungi which are formed by the destructive underground absorbing threads. This, however, is but one of the underground fungi. There are many kinds; some are useful, others are very destructive.

Upon the upper surface of the soil there falls not only rain, but another sort of rain consisting of seeds, dead leaves, insects' bodies, fungus spores, bacteria, and dust.

Every year when the ploughman turns the sod there is a revolution in the whole of these populations.

So far nothing has been said about the roots themselves, which penetrate, explore, and exploit all these layers of dead leaves, soil, and subsoil.

The length of roots produced is very much greater than any one would suppose. A one-year-old Scotch fir seedling when grown in sand produced in a season a total length (branches, etc.) of no less than thirty-six feet of root. The total surface of this root system was estimated to be about twenty-three square inches. This little Scotch fir after six months' growth was laying under contribution a cone of earth twenty to thirty inches deep and with a surface of 222 square inches. In certain kinds of corn the same author estimated the total length of the roots as from 1500 to 1800 feet. S. Clark estimated the length of the roots of a large cucumber plant as amounting to 25,000 yards (fifteen miles), and made out that it was occupying a whole cubic yard of ground.

Clover roots are said to go down to depths of six or nine feet, but many weeds go deeper still. Coltsfoot, for instance, may be found, according to a friend of mine, living at a depth of twenty spades. In Egypt and other places the roots of acacias go down to twenty feet or even further, so that they can tap the water supplies, which are at a great depth.

But a still more extraordinary fact is the manner in which the root-branches arrange to grow in such a way that they search every part of the soil.

The main root in many plants grows straight down, or as nearly as it can do so. Its branches are inclined downwards at a quite definite angle which is often 30°-45° to the surface. Moreover, these branches come off in quite a regular way. Each keeps growing in its own special direction to the east, south-east, or west, or whatever it may be, of its parent root.

Have they some extraordinary sense of the direction of the points of the compass? It is said that if a side root, which is growing, say for instance downwards and westwards, is turned in some other direction, it will after a time resume its original westerly voyage. This fact is a most extraordinary one, if true, but it can scarcely be said that it has been proved, and, as will be shown later, there are other curious facts in the behaviour of roots which might explain the experiment without assuming that roots know the points of the compass.

If one cuts a branch of willow and plants it upside down in the earth, it will very likely take root and grow. Its appearance will be most extraordinary, for the roots will grow downwards, whilst the branches, instead of growing in the direction of the old branches, turn round and grow upwards.[34]

Why do roots generally grow downwards? The fact is so familiar that the difficulty of answering does not, at first sight, seem so great as it really is.

Pfeffer, the great physiologist, has the following interesting comparison. Suppose a man is trying to find his way in the dark, then a single lingering ray of light gives him an impulse to walk towards it.[35] So our root, also in the dark, feels the pull of gravity and endeavours to grow downwards. Others have compared the direction of gravity to the sailor's compass, and suppose that the root is guided in the same sort of way.

But a young, vigorous root making or forcing its way in darkness through stones and heavy earth is a most interesting and fascinating study.

There are the most extraordinary coincidences in its behaviour. It has the property of always doing exactly the right thing in any emergency.

It is of course intended to keep below the ground and in the dark. So we find that if roots are uncovered, they will turn away from the light and burrow into the earth again. They avoid light just as a worm would do.

Roots are of course intended to absorb or suck in water. If there is a drain in the soil or a place where water collects, the roots will grow towards that place. Very often they form a dense spongy mass of fibres which may almost choke the drain. Along a riverside one can often find great fibrous masses of tree roots near the water. But how does the root learn that the water is there and turn away from its original track to find it? It certainly does so!

Then again, Herr Lilienfeld has recently shown that roots seem able to turn away from poisonous materials in the soil and to seek out and grow towards valuable and nutritious substances. He found that peas, beans, sunflower, and other roots were very sensitive to different substances in the soil, and were directly attracted by what was good for them and turned aside from what was unwholesome.

This property and the power of growing towards water probably explain the mysterious sense of direction alluded to above, for roots will take a line which has not been exhausted by their neighbours.[36]

But of all these wonderful properties, the most remarkable is the way in which roots find their way past stones and other obstacles in the soil. They insinuate themselves into winding cracks and crawl round stones with an ingenuity that makes one wonder if they can possibly be without some sort of intelligence.

It is the very tip or end of the young root that seems to be responsible; for if, in the course of its journeyings underground, it should strike a stone or something hard, the root does not grow on and flatten itself.

But some sort of message is sent back from the tip to the growing part which is a short distance behind it. After this message has been received, the growing part begins to curve sideways, so that the tip is brought clear of the obstacle and can probably proceed triumphantly upon its way. The inexplicable part is that the growing part which curves has never been touched at all, but simply answers to the message from the tip.[37]

This is perhaps the most reasonable and intelligent behaviour found in the whole vegetable world, and it is not surprising that Darwin compared the root-tip to a brain.

These extraordinary responses fill one with astonishment, but there are others still more interesting and remarkable. It will be remembered that we have already shown how different the soil is at different levels. The subsoil, soil, and uppermost layers are all quite different from one another.

This may explain why it is that many plants seem to prefer to develop their roots at one particular depth below the surface. Not only so, but they find their own favourite level in the most persevering way.

If, for instance, you sow a barley-corn at too great a depth, the seed germinates and forms a few roots, but it immediately sends out a stem which grows upwards towards the light. As soon as this stem has reached the proper place, which is just below the surface, there is an enormous development of roots, which begin to search and explore their favourite stratum of soil.[38]

In some few cases one can see in a dim sort of way the reason for the level which certain plants prefer. Thus the underground stems of the common Thistle, which are very long and fleshy, are found just a few inches below the level usually reached by plough or spade. This makes it very difficult to tear them out. Even if grubbers with long spikes which reach as deep as these buried stems are driven through the ground, it generally happens that the stems are only cut in pieces and not dragged up. These hardy weeds are not much injured by little accidents of this kind, for each separate bit will form upright thistle stems next year. In fact if one cuts this fleshy subterranean runner of the Thistle into pieces a quarter of an inch long, each piece will probably become a Thistle.

Sometimes indeed these weeds are carried from one field to another by pieces of them sticking in the very machines which are used to eradicate them.

The Bishopsweed is one of the hardest cases. The writer was once ambitious enough to try to dig up an entire plant of this horrid weed. The first foot or so revealed no sign of the end of the branching runners, and it was not until a hole about four feet deep and five feet across had been excavated that there was any sign of an end to the plant.

When it was at last removed, the original deeply buried stem was found to give off branches which again branched in a most complicated manner, until almost every green shoot of Bishopsweed[39] within a space six feet in diameter was seen to be really a branch of this one original plant! So to eradicate the plant it would have been necessary to dig over the whole garden to a depth of at least five or six feet.

How did the stem get down to such a depth below the surface? This is one of the most curious stories in plant life, and the process which we shall now try to describe has only been explained within the last few years.[40]

The seed of the Wild Garlic (Allium ursinum) lies at first upon the surface of the ground, but it is soon buried by a growth of the stalk of the seed-leaf, which pushes the germ down below the earth. As soon as it is buried, roots are formed and pass obliquely downwards, where they become fixed by forming root-hairs all round themselves. These root-hairs round every root hold its tip firmly in the earth; then these same roots contract or shorten, which of course hauls down the root a little deeper in the earth. One might compare it to a few men hauling down a balloon by ropes attached to the car. About September to November, roots of quite a different character are formed; these explore the surrounding soil and gather in food and moisture.

Then the roots rest during the winter, when the buds and young leaves are being formed. In April the buds begin to push out their leaves and a new ring of roots appear. These April roots are quite different from the September ones. They again fix themselves firmly and then contract, becoming fully a third shorter than they were originally. The bulb is dragged down still deeper below the surface. It flowers in May and fruits in June and July. Then in September the same series of operations begins again. The process goes on until the plant is three to five inches below the ground.

It follows from all this, that every year the roots find new ground to explore and utilize. Nor is the Wild Garlic at all exceptional in this respect. A great many plants have roots which contract and drag the bulb or stem after them deeper into the earth. Something of the same sort happens, for instance, to Bramble branches. They arch or droop over, when growing, so that the end touches the earth. On the underside of the tip, as soon as it begins to rest on the ground, roots are formed. These roots make their way into the ground, and then, when fixed, they shorten or contract, so that the end of the branch is dragged down to a depth of several inches. After this has happened the old branch generally dies away, and a young, vigorous Bramble develops from its buried tip.

Raspberry branches also are often buried; their roots become coiled or rolled in a very curious manner. The end of the root becomes firmly attached in the soil, and then the rest of it revolves like a tendril so as to draw the stem deeper into the earth.[41]

On any ordinary roadside in the country one is sure to find the rosettes of the common Dandelion and of the Rats-tail Plantain (Plantago major). These are two of the most interesting plants in the world, although they are vulgarly common. How is it that their leaves are always at the level of the ground? The stem is always growing upwards; every year fresh circles of leaves are formed above the older ones. Yet the crown of the stem is never so much raised up above the ground that the toe of a boot would be likely to knock it off. It is always kept so deep in the earth, that it is by no means easy to kick or "howk" the crown out of the ground.

The Dandelion root contracts very strongly at the end of the season, and by this shortening or contraction keeps its leaves just at the soil level. The Plantain sends out about forty to sixty oblique downward-growing roots, which fix themselves in the soil by throwing out branch roots. These forty to sixty roots are at first about ten inches long, but, as soon as they are firmly attached, they contract, and pull the stem with its crown of leaves about one-third of an inch deeper. This is just enough to keep the leaves flat on the ground and to prevent any possible injury from passers-by.

So that in finding their favourite level in the soil, plants are often pulled or hauled about by the roots. But they are not always moved by the roots. Even though buried in darkness, they seem able in some way to tell when they are in the most favourable position.

Every gardener knows that Autumn Crocus and other bulbs do not remain in the same position. They wander below ground in a curious and inexplicable fashion.

The Solomon's Seal has an underground, fleshy stem, which prefers to grow at a definite depth. If it is planted close to the surface, then the point of the next year's little fleshy bud turns downwards; next year it again turns downwards, and so on every year, until the stem has reached its proper depth. Then it grows horizontally. Similarly, if it is planted too deep it grows upwards.

Thus if one wishes to realize the underground life of plants, one must picture to oneself:—

1. The usual descending roots, whose system of branching may be compared to the ordinary branching above ground. It is often not unlike the reflection in water of the tree itself, such as one might see on a fine winter's day along the shore of some still lake.

2. The bold, exploring, horizontal runners of Couchgrass, Thistle, Bishopsweed, etc., vigorously pushing their way at a depth too great for the gardener's spade.

3. All sorts of bulbs, runners, and roots being slowly hauled or dragged about till they get into exactly the right position, but never remaining for two years in exactly the same place. All have their favourite depth[42]—

The water evaporating on the surface of the soil must, as it rises from the permanent water-level below, pass the gauntlet of all these thirsty rootlets and their hairs. Tree-roots will be ready to intercept it at ten feet depth, many herbaceous plants will suck it in at depths of five to six feet, and in the upper layers of soil it will have to pass root-system after root-system from Asparagus to Paris, so that very little will be lost.

Perhaps of more importance are the bacteria-germs, and dissolved mineral salts in the rainwater as it trickles down from the surface. The soil particle acts as a filter: at every inch of the descent some of the bacteria and salts will be left, so that by the time the level of Asparagus has been reached there will be exceedingly few, and the water is comparatively speaking pure. The effect of this vigorous underground life is often visible on the surface. Roots, and particularly tree-roots, are often extraordinarily strong. Kerner, in his invaluable Natural History of Plants, has a beautiful picture of a young larch tree which had grown in a fissure of a huge boulder.

In attempting to grow, the root had forced up part of this stone. It was estimated that it had lifted a weight of 3000 lb., though it was only some ten inches in diameter.

Along a dry-stone wall, or even near houses, the growth of tree-roots very often damages the entire wall, which may be entirely overthrown if the tree is too near. The force of the growth of the roots is so great that even a six-foot stone wall cannot keep them down.

Quite a young seedling root, in forcing itself through the soil, may exercise a pressure of two-thirds to four-fifths of a pound!

This is of course necessary, if one remembers that it has to drive itself through the earth, pushing aside and compressing the earth particles along its course.

CHAPTER VII
HIGH MOUNTAINS, ARCTIC SNOWS

The life of a cherry tree—Cherries in March—Flowering of gorse—Chickweed's descendants—Forest fires in Africa—Spring passing from Italy to the frozen North—Life in the Arctic—Dwarfs—Snow-melting soldanellas—Highland Arctic-Alpine plants—Their history—Arctic Britain—Edelweiss—An Alpine garden.

IT is impossible to understand and very difficult to explain the sort of life and consciousness which is enjoyed by plants.

That they do live is obvious; we know instinctively that they enjoy fine weather in summer and gentle showers in spring, but we cannot prove it.

Much of a plant's life is concealed and hidden from us. Even the few explanations which have been given by certain observers are by no means generally accepted.

This is true even as regards the case of the Cherry tree, which has been experimented with, and fought over and argued about by botanists, and yet we only know a very little about its inner life.

When the leaves fall in autumn, next season's buds are already formed and are then about one-eighth of their full size. At this time the tree contains enormous quantities of food-stores, for the whole season's work of the leaves has been accumulating until this moment. During the long winter's "sleep" the tree is by no means at rest. It is arranging and packing up those stores in the safest place and in the most convenient form.

Just as a bear, before it retires to sleep during the winter, takes care to get as fat as possible, so the Cherry turns its starch to fat, and stores it away in the innermost and least exposed parts of the tree, that is in the central wood. As soon as the winter ends, and indeed before it has ended, preparations are beginning for the great moment of the year. For weeks there is a slow, gradual, almost imperceptible growth of the buds, then they develop with a rush, and in six to ten days double or treble their weight. Then comes the supreme moment, for the flower-buds suddenly burst open and the Cherry is in active and vigorous bloom and covered all over with exquisite blossoms. All last year's fats and starches are rapidly used up. Very soon the young leaves are beginning to make sugar and other food, which give some help during the ripening of the fruit.

The flowers are actively at work. One of our usual misconceptions as to the nature of a flower is that it is an emblem of peace, of restful enjoyment, of serene contemplation of its own beauty. That is very far from being the truth. The petals are actively, vigorously working. If one could take the pulse of a petal, which shows the rapidity of its breathing, one would find that it is twice as fast as that of the leaf. The work of changing water into vapour and pouring it out goes on three times as quickly in the petals (as compared with the leaves). Moreover their temperature is higher, and often distinctly above that of the atmosphere.

This feverish activity of the flowers themselves is matched by the hurrying crowds of excited and exhilarated insects which are searching every blossom.

No wonder that the Japanese Prime Minister, in the midst of their great and famous war, invited the whole cabinet to spend an afternoon watching the cherry trees in bloom!

Not merely strong, forcing heat, but a little judicious cold, is necessary to get out the flowers and to ripen the fruit.[43]

Most flowers have very much the same general history as the cherry, but it must not be supposed that they are all alike. The differences are very interesting and curious.

Thus, for example, plants of our common Gorse, furze, or whin may be found in bloom at almost every season of the year. There are at least four seasons when there is that tremendous display of golden blossom which made the great Linnæus fall on his knees and burst into tears. These are about the 22nd March, 24th May, 15th August, and 21st November; yet there are enough odd flowers blooming in almost every month to give some cause for the saying, "The gorse is out of bloom when kissing is out of favour." The last practice, though uncleanly and dangerous, not only on general grounds, but on account of bacterial germs which may be transferred, has been authoritatively condemned in the United States, but it is still more or less popular in other countries at all seasons.

The Chickweed and some other of our annual weeds show a hardy disregard of climate. Its seeds germinate and grow at any time, so that flowers and seeds can be formed whenever there is a spell of favourable weather. Now one chickweed can produce 3000 seeds. Suppose that there are only five generations in the year, which is a very low estimate. Then one seed of chickweed might produce 3000 × 3000 × 3000 × 3000 individuals in one season!

Other plants show much the same tendency. In fine warm autumns a great many annuals bloom a second time. It is on record that forty-four spring species bloomed in one warm November. At the Cape and in other warm climates many of our annuals do not die at the end of autumn, but go on growing. They become perennial.

It is even possible to make a Tree Mignonette by pinching off the flower-buds, though this plant is usually an annual.

In fact plants are not absolutely confined to one rigid scheme, but they can alter and modify their blooming time if they find it convenient to do so. In the Mediterranean some blossom in early spring and others in late autumn, whilst in the dry, hot, and dusty summer very few flower.

In Central Africa during the dry season forest fires are by no means rare. The trees are scattered, and the ground is only covered by dried and withered grasses and sedges. One sees in the distance a rolling cloud of smoke, and soon one comes to a line of flame. It is not dangerous, not even very impressive, for a jump of three feet carries you over the flame and on to a desolate wilderness of black cinders, out of which stand up the scorched trunks and half-burnt branches of gaunt, naked trees. A day or two afterwards, bright blue and white and yellow flowers break out of those scorched branches and also from the ground.

It is difficult to understand why this happens, but certainly it is good for the flowers, which can be seen by insects from a long distance.

But these are unusual cases. Generally the warm breath of spring wakes up the bulbs and buds, and one after another has its moment of flowering.

Spring travels towards the North Pole at an average rate of four miles a day.

A pedestrian visiting Italy in the end of January might follow the spring northwards, and if he wished to accompany it all the way, it would be quite possible to do so without exceeding an ordinary day's march. He would have to reach North Germany by the end of March, Sweden in May, and by the end of June and July would find spring beginning in the desolate Arctic regions.

Of course the presence of mountains would make this tour a little difficult and devious, but still it is quite a possible undertaking. It would be very interesting, for he would be able to watch the cold and frost and chilliness of winter disappearing as the sun's rays thaw out a greater and greater extent of the cold and frozen North.

The life of an Arctic plant is truly set in the midst of many and great dangers.

For 250 days the ground is hard frozen and the temperature never above the freezing-point. About the end of May it begins to rise a little, but the plant has to crowd the whole of its life, its flowers, fruits, and seeds, into the space of two months!

About the 23rd to the 29th June the first flower appears, then follows strong, active growth in uninterrupted sunshine during July and August. The flowers are brilliant in colour and richly produced. The tiny dwarf Arctic plants are covered all over with blue or golden yellow or white blossoms. All is in full activity and luxuriance. Then suddenly, in a night, the icy grasp of winter falls upon them.

Hard-frozen flowers, buds, and ripening fruits remain chilled and incapable of life from the 30th August until the end of May.

Of course, under such conditions, these hardy and vigorous little plants cannot become trees or shrubs. To show the effect of the climate upon them, a few British plants which are also Arctic may be compared.

These wretched little dwarfs seem, however, to have pretty long lives, and, as we have said, deck themselves in the most gaudy colours every summer.

In the Alps of Switzerland and other temperate countries, the flowering season is also a very short one and soon over. It is often not more than six weeks, yet in that short time the rich blue of the Gentian, the Alpine Roses, Soldanellas, Campanulas, and many others make some of these grass slopes high up in the mountains a perfect garden of loveliness.

Sometimes in passing over the snowfields of Switzerland just before spring, one notices the pretty violet flowers of the Soldanella swaying to and fro in the wind above the unmelted snow. One does occasionally see in this country the Snowdrop in the midst of snow, but then it has fallen after the Snowdrop had blossomed.

The Alpine Soldanella flowers whilst the earth is still covered. It begins as soon as the ground below the snow is thawed. Each little developing flower-stalk melts out a grotto in the snow above itself, and so bores, thawing its way up into the air above. It has already been mentioned that, inside a flower, the temperature is often higher than the surrounding air. It is this higher temperature of the flower which thaws a little dome or grotto in the snow above the head of the flower.[44] When a flock of sheep are covered by a snowdrift, a similar hollow is formed above them by their breath and the high temperature of their bodies: they often seem indeed to be little or none the worse for being buried. The Soldanella melts its way in just the same manner.

In this country we have no such magnificent chain of mountains as the Alps, and yet we find on the Scotch and Welsh mountains quite a number of real alpines.

There are, for instance, such flowers as Sea-pink (Armeria), Sea Plantain (Plantago maritima), Scurvy-grass, and others, which can be found on windy, desolate gullies and corries high up on the Highland hills, and which also occur on the sea-coast, but never between the seashore and the tops of the mountains. You might search every field, every moor, and every riverside throughout the country, but you would not discover those three plants anywhere between the seashore and the summits.

At first sight it seems quite impossible to explain why this should be the case. But all those three plants are found in the Arctic regions, and the explanation is in reality quite simple.

At one time the shores of England and Scotland formed part of the Arctic regions. Ice and snow covered the hills and mountains; huge glaciers occupied the valleys and flowed over the lowlands, plastering the low grounds with clay which they dragged underneath them, and polishing and scratching any exposed rocks.

When the ice began to melt away and left free "berg battered beaches" and "boulder-hatched hills," Lincolnshire and Yorkshire must have been like the Antarctic regions in those days. This is how Dr. Louis Bernacchi describes the Antarctic continent:—

"The scene before us looked inexpressibly desolate.... No token of vitality anywhere, nothing to be seen on the steep slopes of the mountains but rock and ice.... Gravel and pebbles were heaped up in mounds and ridges. In some places these ridges coalesced so as to form basin-shaped hollows. Bleached remains of thousands of penguins were scattered all over the platform, mostly young birds that had succumbed to the severity of the climate."

Great Britain must have been just as savage and desolate when these hardy little Arctic plants colonized the shingles and rooted themselves amongst the rocks.

They covered not only the seashore, but they probably made a settlement wherever rock or land of any kind was exposed. These original settlers have had three bands of descendants. One band has remained ever since on the seashore of Great Britain; another set gradually travelled northwards. As the ice melted away, leaving the land bare, first in Denmark, then in Norway, and finally in Greenland, this second set followed it, until now we find them far to the northward, populating the Arctic regions of to-day just as they did those of Britain in the Great Ice Age.

The third set of descendants would at first cover all the land and rocks of the lower hills and valleys near the sea; then as the ice and snow melted and exposed the higher mountain sides, they would climb the hills and eventually reach the exposed summits where they are now living. There they find themselves in an impossible, savage sort of climate, in which they alone are able to exist. Violent storms, drenching mist, scorching sunshine (when the rocks become so hot that it is almost impossible to touch them), rainstorms and months of snow and hard frost, cannot kill Scurvy-grass, Seathrift, or Plantain, but there are few other plants which can stand such conditions. Lower down on the flanks of the hills and in the valleys, they have long since been dispossessed of the rich and fertile lands by plants which can grow more rapidly and luxuriantly.

The little Alpine Creeping and Least Willows, for instance, some of which get up to 3980 feet in Breadalbane, are mere dwarfs only a few inches high, and totally different from their allies in the fertile lowlands, which are trees eighty to ninety feet high.

Some of the Alpine plants which also occur in the Arctic regions have not even been able to survive by the seaside in Great Britain. Their nearest allies are in the Norwegian mountains.

It would be impossible even for shrubs to stand the violent winds and snowstorms of these summits. Alpine plants are generally low-growing mats. They are also often clothed all over in cottonwool, such as the Edelweiss. This probably keeps them from losing too much water during the dry season, when the rocks on which they grow are strongly heated by the sunlight.

Yet, like the Arctic plants, they have rich, deep, and brilliant colours.

A queer point is that they have got so accustomed to this stormy and perilous existence that it is extremely difficult to grow them in a garden. Like mountaineers, they dwindle and pine away in the richer soil and softer air of the low grounds.

To make an Alpine garden, rocks and stones must be arranged with pockets and hollows, like natural crevices and basins, between them. Rich leaf-mould must be placed in these hollows. There must be good drainage, and as much sunlight as one can possibly get.

CHAPTER VIII
SCRUB

Famous countries which were covered by it—Trees which are colonizing the desert—Acacia scrub in East Africa, game and lions—Battle between acacia and camels, etc.—Australian half-deserts—Explorers' fate—Queen Hatasu and the first geographical expedition recorded—Frankincense, myrrh, gums, and odorous resins—Manna—Ladanum—Burning bush—Olives, oranges, and perfume farms—Story of roses—Bulgarian attar of roses—How pomade is made—Cutting down of forests and Mohammed.

A scrub or Half-desert does not seem at first sight to be in the least interesting.

But if one remembers such places as Cordoba, Seville, Florence, Genoa, Sicily, Athens, Constantinople, the great cities of Ephesus, Corinth, etc., of St. Paul's Epistles, Persia, Arabia, Palestine, and Carthage, surely the countries which have had such splendid histories deserve a chapter to themselves. What achievements in war, in art, in literature, and in romance are connected with these lands bordering the Mediterranean or fringing the great deserts of Sahara and central Asia!

The animals which belong to such country are also interesting. It is the home of the camel, ass, horse, donkey, not to speak of the giraffe, rhinoceros, gazelle, antelope, zebra, lion, and hyena.

The plants are full of interest too, and some of them are of great importance to man. The Olive, Orange, Fig, Roses, and many perfumes and spice-trees, are natives of scrub. In fact, it is the real centre of all gums, frankincenses, and myrrhs.

As man depends upon plants and animals, and as animals also are dependent on the plant world, it is the climate which really is responsible for everything.

The world of plants is entirely and exactly regulated by the character of the climate. What, then, is the climate of scrub?

Those countries enjoy brilliant sunshine, cloudless skies, and yet there is sufficient rain to permit of irrigation and to prevent the unmitigated desolation of the desert. When, as has happened in many of these famous lands, the forests have been cut down and the aqueducts have been neglected, they become arid, dry, and almost useless. But when carefully and industriously worked, as they were in the days of Greece, Carthage, and Rome, they produce results which will for ever live in the history of the world.

The meaning of such half-desert climates and of the scrub which covers them has been already suggested.

The scrub is trying to occupy the desert.

If one takes the sternwheel steamer at the First Cataract of the Nile and passes southwards, the desolation of black rock and "honey-coloured" sand of the Libyan Desert is at first unbroken. But here and there the thorny trees of the "Seyal". Acacia show the beginnings of a scrub region. Much further to the south, those acacias and others become great forests which extend all along the south of the Sahara Desert and furnish the valuable gums of the Soudan.

If one passes southward through this forest of acacias, it alters in character. The trees become taller, closer together, and climbing plants and undergrowth become more frequent. Still further south, one finds the regular tropical forest which is characteristic of the tropics everywhere.