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FIELD, FOREST AND FARM

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FIELD, FOREST AND FARM

THINGS INTERESTING TO YOUNG NATURE-LOVERS, INCLUDING SOME MATTERS OF MOMENT TO GARDENERS AND FRUIT-GROWERS

BY
JEAN-HENRI FABRE
Author of “The Story-Book of Science,” “Our Humble Helpers,” “Social Life in the Insect World,” etc.
TRANSLATED FROM THE FRENCH
BY
FLORENCE CONSTABLE BICKNELL

NEW YORK
THE CENTURY CO.
1919

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Copyright, 1919, by
The Century Co.

Published, September, 1919 [[v]]

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CONTENTS

[[3]]

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FIELD, FOREST AND FARM

CHAPTER I

THE STAFF OF LIFE

With his nephews as willing companions and eager listeners, Uncle Paul continued his walks and talks in the pleasant summer afternoons.

“Bread is made of flour,” he began, “and flour is wheat reduced to powder under the millstone. What an interesting mechanism that is, the flour-mill, driven by water, by the wind, sometimes by steam! What wearisome effort, what waste of time, if we had not this invention and were forced to do its work of grinding by sheer strength of arm!

“I must tell you that in ancient times, for want of knowing how to grind wheat, people had to content themselves with crushing it between two stones after parching it a little over the fire. The coarse meal thus obtained was cooked in water to a sort of porridge and eaten with no further preparation. Bread was unknown.

“Later the plan was hit upon of kneading the meal with water and of cooking the dough between two hot stones. Thus was obtained a crude sort of biscuit, about as thick as your finger, stodgy and hard, [[4]]and mixed with charcoal and ashes. It was preferable to the porridge, the insipid paste, of the earlier time, but far inferior to the poorest bread of to-day. To make a long story short, by trial after trial success was at last attained in the making of bread like ours. It became necessary then, without possessing anything to compare with our mills, to grind wheat in large quantities.

Wheat

“Flour was obtained by triturating the wheat in a hollowed stone with a pestle. This latter was sometimes light enough to be operated directly by hand; sometimes, to produce quicker results, it was so large and heavy that it had to be turned in its stone mortar with the help of a long bar. Such was the first mill. With appliances of this sort I leave you to imagine how long a time was required for the production of a single handful of flour. For bread enough to feed one person at one meal, wretched slaves were kept toiling from morning till night and from night till morning in turning the pestle.” [[5]]

“What cruel masters they must have had!” exclaimed Emile.

“Yes, the slaves were harnessed to the bar like beasts of burden; and when, weakened with fatigue, they did not go fast enough, a rawhide was applied to their bare shoulders. These unfortunate millers were poor wretches taken in war and afterward sold in the market with the same indifference with which a drover sells his cattle. Such, then, were the hardships that led the way to the modern mill which to-day, with a few turns of its water-wheel, and to the cheerful accompaniment of its tick-tack, can make flour enough for a whole family.

“But let us leave the mill and turn our attention to the following interesting experiment. Take a handful of flour and with a little water make it into dough. This done, knead the dough with your fingers over a large plate while an assistant moistens it continually with water from a pitcher. Keep the dough well in hand and continue kneading it, flattening it out and gathering it together again, turning it over and over under the fine stream of water poured from above.

“Examine carefully the water that passes over the dough and washes it. It falls into the plate as white as milk, showing that it carries with it something from the flour. This something will finally settle at the bottom of the liquid, and we shall find it to be a substance not unlike the starch used for starching linen. In fact, it is starch, or fecula, as the chemists call it—neither more nor less. The [[6]]starch used in the laundry is obtained in considerable quantities by similar means: dough is washed and the whitened water, left undisturbed, deposits a layer of starch which has only to be gathered together and dried.[1]

“So much, then, is made clear: flour contains starch, but it contains something else also. There is a limit beyond which the washed dough yields no more starch; it is useless to knead it, the water falls colorless into the plate. What remains in one’s hands after this prolonged washing is a soft, gluey substance, having something of the elastic quality of rubber. Grayish in color, it has a rather pronounced odor. When dried in the sun, it becomes hard and translucent like horn. It is called gluten from its gluelike character, its viscosity.

“Now this substance, so unattractive in appearance, all soft and sticky and getting clogged between the fingers—this gluten, in short—do you know what it is? Don’t try to dispute me, for what I am going to tell you is the exact truth. In its composition gluten does not differ from flesh. It is vegetable flesh, capable of becoming animal flesh by the simple process of digestion, without any material loss or gain. Therefore it is gluten, first and foremost, that gives to bread its great nutritive value.

“Of all the cereals wheat contains the most gluten, with rye holding second place. Maize and rice, as well as chestnuts and potatoes, are wholly lacking [[7]]in this ingredient; and for that reason flour made from them, rich though it be in starch, is not at all the kind of flour for bread. This will explain to you the superiority of wheat over all other farinaceous grains.

“Wheat, the only cereal that can give us white bread, that superior bread which nevertheless is not always to your taste unless spread with a little butter, does not grow in all countries. Open your atlas and run over with your finger the countries bordering on the Mediterranean; your travels will embrace the principal regions where wheat flourishes. Farther north it is too cold for the successful culture of the precious cereal; farther south it is too warm.

Rye

“But that is not all. In the privileged regions not every district is adapted to this incomparable crop: wheat needs the mild temperature and fertile soil of the plains, not the harsh climate and dry slopes of the mountains. Let us consider France in particular. Its plains produce excellent wheat, but not enough to feed the entire population; therefore in the hilly and cooler regions, where this cereal cannot be raised, recourse is had in the first place to rye, which yields a bread that is compact, brown, and heavy, but on the whole preferable to any other except, of course, wheat. This rye bread is the customary [[8]]food of the country in the greater number of our departments.

“The raising of rye becomes in its turn impossible in regions too cold and too sterile. There then remains, as a last resort, barley, the hardiest of cereals, which is found in the mountains until we reach the neighborhood of perpetual snow, and can be raised even in the frigid climate of the extreme North.

“You ought to taste the miserable bread made from barley in order to find our bread good—or, I might better say, in order to find it an exquisite dainty even without butter or jam. Barley bread is full of long bristles that stick in the throat; it contains more bran than flour; it is bitter, stodgy, and of a disagreeable odor. Oh, what sorry stuff! And yet many have to be content with it, and are only glad if they can get enough of it.

Barley

“In the greater part of the world wheat, widely distributed by commerce, furnishes bread only for the tables of the rich. The rest of the population knows nothing, as a rule, of this article of food, has never so much as seen it, and at most has only heard of it as a rare curiosity. In place of bread the people eat here one thing, there another, according to the country. Asia has rice, Africa millet, America maize. In India and China the people have hardly anything to eat but rice boiled in water with a little [[9]]salt. Half the entire world has practically the same diet.

“The plant that produces rice has a stalk resembling that of wheat, but instead of ending in an upright ear it bears a cluster of feeble and pendent branches, all loaded with seeds. The leaves are narrow and ribbon-shaped, rough to the touch. This plant is aquatic. In order to flourish, it must send down its roots into the submerged mud and spread its foliage, excepting the tip, in the flood. Marshy shallows, inundated a part of the year, are adapted to its cultivation.”

“But what do they do where there are no such marshes?” asked Louis.

Rice

“When such marshes are lacking, the ingenious Chinaman floods the lowlands with water from some near-by stream until the ground is all soft and muddy. He then draws off the water through a series of little canals, and works the mud with a light plow drawn by a buffalo, a kind of ox with a long beard hanging from its chin and a mane waving on its back.

“The seed once sown in the furrows and the young plants started, the water from the stream is again made to flood the fields, where it remains until harvest time. Then for the second time it is drawn off, and the reaper, sickle in hand and with the black mud up to his knees, cuts down the rice-laden tops of the stalks. [[10]]

“Maize, or Indian corn, is the staple food of South America, as rice is that of Asia. Many call it Turkish wheat, a name doubly inappropriate, for in the first place this grain is not indigenous to Turkey, but to America, and in the second place it has nothing in common with the wheat from which bread is made. From America its cultivation has spread to our part of the globe.

“The ear of maize is very large and is composed of full, rounded kernels, yellow and shiny, closely packed in regular rows. Like rice, maize furnishes a fine flour of pleasing appearance but lacking in one essential: it contains no gluten. Hence the utter impossibility of using either rice or maize for making bread, despite the good appearance of the flour made from them.

“Nevertheless maize is a very wholesome article of food, and one of great value in the country, where the appetite is sharpened by open air and hard work. Only it is not in the form of bread that it best yields its nourishment, but rather in that of porridge, or boiled meal and water.” [[11]]

[1] Laundry starch is now obtained chiefly from rice and from pulse.—Translator. [↑]

[[Contents]]

CHAPTER II

THE HISTORY OF TOBACCO

“Before taking the form of the powder which the user of snuff pushes up into his nose to tickle his nostrils and promote sneezing, before being rolled into the cigar or reduced to that crisp, moss-like substance which the smoker stuffs into his pipe, tobacco has had a previous existence as a plant bearing this same name. A stalk about one meter in height, large, clammy leaves of a strong odor, bright red flowers each shaped like a narrow funnel and expanding into the five points of a star at the orifice, dry capsules filled with innumerable little seeds—there you have the tobacco plant.

Tobacco Plant

“Only the leaves are used, and these only after undergoing certain processes that intensify their natural properties and cause them to lose their green color. Rolled into compact little cylinders, they become cigars; cut very fine, they take the form of smoking tobacco. Reduced to powder, they furnish what is known as snuff.

“America, the same land to which we owe the [[12]]potato, also gave us tobacco. When, almost four centuries ago, Christopher Columbus discovered the new world, one of the first landings he made was on the large island of Cuba. Apprehensive of danger in the forests from the savage tribes on every side, Columbus sent scouts ahead to reconnoitre the country.

“The sailors forming this party encountered on the way, to their extreme surprise, numerous Indians, both men and women, holding each a sort of lighted fire-brand between the teeth and inhaling the smoke. These fire-brands, called ‘tabagos,’ were made of a plant rolled up in a dry leaf. There, then, were the first smokers and the first cigars recorded in history.

“The natives of Cuba and the neighboring islands had, we infer, been addicted to smoking for a long time, probably for centuries, when the Europeans first appeared among them. They had their rolls of dry leaves, or tabagos, and their smoking appliances of soft stone or baked clay, appliances called by us ‘pipes’ and by them ‘calumets.’ Tobacco, in fact, played a prominent part in their medicine, their superstitious observances, and their political assemblies.

“Consulted as to future events, the soothsayer first of all inhaled the smoke of several tabagos, while the other persons present, seated in a circle, vied with one another in the energy of their smoking, their ultimate object being to enwrap themselves in a dense cloud. Then from the midst of this cloud [[13]]the soothsayer, his imagination wrought to a high pitch by the fumes of the tobacco, delivered his oracles in unwonted terms that made the hearers believe they were listening to the voice of God.

“A like ceremony was observed in the assemblies held for discussing public affairs. Seated on a stone and inhaling the smoke from his calumet, the orator who was about to take the floor waited in passive silence while the chiefs of the nation approached him, one at a time, to blow into his face plenteous puffs from their pipes and to commend to him the interests of the tribe. These fumigations concluded, the orator abandoned himself to his eloquence amid the enthusiastic acclaim of the assembly.

“Seeing the islanders smoking, Columbus’s companions wished to try this singular custom for themselves. To the gratification of this desire the Indian lent his ready assistance: he showed them how the tabago is rolled, and how the calumet is filled and lighted. Though history is silent on the subject, it is clear that the first sailor to undertake the inhalation must have been seized with that fearful nausea which no novice in smoking can escape. A stomach of any delicacy would have been forever repelled; the harsh gullet of the mariner found a certain charm in the thing when once the trying experiences of initiation were over.

“The taste for smoking was so soon acquired that, on their return to Spain, the companions of Columbus very quickly extended this Indian custom in their own country. Before long, too, there was discovered [[14]]a new way to use tobacco: some one conceived the idea of reducing the leaf to a dry powder and stuffing it into the nostrils, sniffing with each pinch of the powdered substance. The Indian had discovered smoking tobacco; the European in his turn invented snuff.

“Spain and Portugal numbered their smokers and snuff-takers by the thousand when, in 1560, tobacco made its first appearance in France. Nicot, French ambassador at Lisbon, sent as an object of curiosity to his sovereign queen, Catherine de Médicis, some seeds of the fashionable plant and a box of tobacco in powdered form. Charmed with this gift, the queen quickly contracted the habit of taking snuff. To please her, tobacco was cultivated, and snuff-takers soon became numerous in all the provinces. It was said that a certain great personage of the period took as much as three ounces daily. He certainly must have had his nose well tanned.

“From one nation to another the use of tobacco gradually spread, but not without serious opposition. The Turks are to-day passionately addicted to smoking, extremely fond of their long pipes; yet hear what sort of a reception they at first gave to tobacco. Against smokers and snuff-takers their emperor, Amurat, issued an edict severe to the point of cruelty. Every delinquent was condemned to receive fifty strokes with the rod on the soles of his feet.”

“That ought to have driven tobacco out of the country in short order,” remarked Jules. [[15]]

“That was merely a warning to first offenders,” returned his uncle. “For a second offense the luckless person caught in the act had his nose cut off. It was a radical measure to discourage the snuff-taker: no more nose, no more snuff. But the smokers, after this horrible mutilation, persisted in their smoking.

“A king of Persia devised what he thought would cure even this habit: every one caught with a pipe in his mouth had his upper lip cut off. At the same time, of course, every nose proved guilty of snuff-taking fell under the executioner’s knife. But the atrocious edict of the Persian king proved as futile as that of the Turkish emperor. Despite all the noses struck off, all the lips cut away, all the feet made to tingle under the rod, the use of tobacco still continued to spread. These fruitless severities had to be abandoned.

“Other regulations sprang up here and there, less cruel, but sufficiently fruitful in fines, imprisonments, vexations of all sorts. Still nothing was of any avail; smokers and snuff-takers remained incorrigible. Finally, taking wiser counsel, the government authorities conceived a plan for making this passion, which no severity had been able to subdue, yield them large revenues. The government itself became exclusive vender of the very article it had at first proscribed with such rigor. France alone derives a yearly revenue of almost three hundred million francs from the sale of tobacco.” [[16]]

[[Contents]]

CHAPTER III

THE ORIGIN OF FERTILE SOIL

“Fertile or arable soil,” resumed Uncle Paul, “constitutes only the surface layer of earth, that which is worked by the farmer’s implements and yields nutriment to the roots of plants and promotes their development. In one place you will see bare rocks and utter barrenness; in another you find fertile soil to a depth of an inch or two, scantily carpeted with grass; and again, in a third, you come upon rich earth so deep as to maintain abundant vegetation. But nowhere does this fertile layer have an indefinite thickness: at a depth never very considerable a subsoil having the qualities of the neighboring mountains is sure to be found. How then has there come to be formed this layer of earth whence is derived all the nutriment required by plants, animals, and men?

“Undermined all winter, and even the whole year round on high mountains, by the ice that forms in their slightest fissures, rocks of all kinds break into small fragments, divide into grains of sand, fall into dust, and furnish the powdery mineral matter which the rain washes away and deposits in the valleys. This as a rule is the origin of broken stones, sand, clay, and fertile soil. Ice by its expansive force has [[17]]detached them from the tops of mountains and the waters have swept them away and carried them further. One can form an idea of the action of ice in crumbling rocks to make soil of them and enrich the valleys, by examining the surface of a hard road at the moment of thawing.

Firm underfoot before freezing, this surface loses its firmness after a thaw and is pushed up here and there in little finely-powdered clods. At the moment of freezing, the humidity with which the soil was impregnated turned into ice which, increasing in volume, reduced to fine particles the surface layer of the road. When the thaw comes, these particles which the ice no longer holds together form first mud, then dust. In exactly this manner arable land was formed by the disintegration of rocks of all kinds, which were reduced to particles by the action of frost.

But soil suitable for agriculture contains not only powdery mineral matter, but also a little mold from the decomposition of vegetable matter. To give you an idea of the causes which from the very earliest times have little by little fertilized this rock-dust with vegetable mold, let us take the following example.

Geography has taught you what a volcano is. It is a mountain whose summit is hollowed out in an immense funnel-shaped excavation called a crater. From time to time the ground trembles near a volcano and formidable noises similar to the rolling of thunder and the booming of cannon are heard [[18]]from the depths of the mountain. The crater throws up into the air a lofty column of smoke, dark by day, fiery red at night. All at once the mountain is rent and vomits up through the crevices a stream of fire, a current of melted rock, or lava. Finally the volcano quiets down; the source of the terrible flood dries up. The streams of lava harden and cease running; and after a lapse of time which may be years they become quite cold. Now what is to become of this enormous bed of black stone similar in character to the slag from a forge? What will this sheet of lava covering an area of several square miles produce?

“This desolate, blasted expanse seems destined never to be clothed with verdure. But in any such assumption one would be mistaken. After centuries and centuries a vigorous growth of oaks, beeches, and other large trees will have taken root there. In fact, you will see that air, rain, snow, and, above all, frost attack in turn the hard surface of the lava, detach fine particles from it, and slowly produce a little dust at its expense. On this dust there will spring into being certain strange and hardy plants, those white or yellow patches, those vegetable incrustations, calculated to live on the surface of stone and known as lichens. These lichens fasten themselves to the lava, gnaw it still more, and in dying leave a little mold formed from their decaying remains. On this precious mold, lodged in some cavity of the lava, there is now a growth of mosses which perish in their turn and increase the quantity [[19]]of fertilizing material. Next come ferns, which require a richer soil, and after that a few tufts of grass; then some brambles, some meager shrubs; and thus with each succeeding year the fertile soil is added to from the new remnants of lava and mold left by the preceding generation of plants that have gone to decay. It is in this way that gradually a lava-bed finally becomes covered with a forest.

“Our own arable land had a similar origin. Sterile rocks, hard as they are, contributed the mineral part by being reduced to dust through the combined action of water, air, and frost; and the successive generations of plant-life, beginning with the simplest, furnished the mold.

“Notice how admirably, in the processes of nature, the smallest of created beings perform their part and contribute as best they can to the general harmony. To produce fertile soil there is needed something more than the frosts and thaws that crumble the hardest rock: there is need of plants hardy enough to live on this sterile soil, such as tough grasses, mosses, lichens, which gnaw the stone. It is through the medium of these rudimentary plants, so pitiful in appearance and yet so hardy, that the dust of the rocks is enriched with mold and converted into a soil capable of bearing other and more delicate plants.

“It is not in cultivated fields that you will find those thick carpets of mosses and lichens, valiant disintegrators of stone; it is on the mountain-tops that they can be seen at their work of crusting over [[20]]the smooth rock in order to convert it into fertile soil. It is from these heights that this fertile soil has descended, little by little, washed down by the rain, until it has fertilized the valleys. This work is going on all the time; in hilly regions plants of the lowest order are constantly adding to the extent of arable land. The little threads of rain-water that furrow these regions carry away with them some of this humus and bear it to the plains below.

“What a worthy subject for our thoughtful study is this formation of arable soil by these legions of inferior plants, obscure workers indefatigably crumbling the rock! What immense results obtained by the simplest means!” [[21]]

[[Contents]]

CHAPTER IV

DIFFERENT KINDS OF SOIL

“Four substances, mingled in very variable proportions, enter into the composition of fertile soil, or arable land, namely: sand or silica, clay, limestone, and humus, or vegetable mold. Each one of these ingredients separately would make but very poor soil, quite unsuited for agriculture; but united, mixed together, they fulfill the conditions necessary to fertility. Arable land generally contains all four, with the predominance sometimes of one, sometimes of another. The soil takes the name of its most abundant constituent. Thus have arisen the names, silicious soil, argillaceous soil, calcareous soil, and humous soil, to designate the fertile lands dominated respectively by sand, clay, limestone, and humus. Compound terms are also used. For example, when it is said of a certain soil that it is argillo-calcareous, it is meant that clay and limestone are its chief constituents.

“Sand consists of particles, more or less minute, of very hard rock, sometimes opaque, sometimes as transparent as glass, and always easily recognizable by its property of emitting sparks when struck with steel. Flint and white pebbles belong to this kind of rock, which is called silex, silica, or quartz. [[22]]These three expressions mean about the same. Sandy soils have little consistency, are easily permeated by water, and freely absorb the sun’s heat, which makes them very subject to drought.

“The name of granite is given to a rock composed chiefly of silica and which forms whole mountains, as in central France and in Brittany. The soil formed by the gradual disintegration of this rock is sometimes called granite soil. It is not very good for agriculture. Chestnut trees prosper in it, as well as certain wild plants characteristic of this kind of land. The principal ones are the various species of heather and the purple digitalis. Heather, with its dainty little pink blossoms, carpets in richest abundance the poorest of sandy soils. The purple digitalis is a large-leaved plant whose flowers, red on the outside, striped with purple and white inside, are arranged in a long and magnificent distaff reaching almost to the height of a man. The flowers are in the shape of long tun-bellied bells or, rather, glove-fingers; hence the plant is sometimes called foxglove, sometimes lady’s fingers.

“The soil composed of substances thrown up by volcanoes is also sandy, and is called volcanic soil. It is generally black and sometimes very fertile.

“Sandy-clay soil is found in the valleys of great rivers. It is the most fruitful and the easiest to cultivate. Such are the soils of the Rhone valley, the valley of the Loire, and that of the Seine. It is still more fertile if it is flooded by the stream at high water. Then the river deposits a rich slime [[23]]composed of clay and organic matter washed down by the current.

“The soil of heathy or shrubby land is composed of fine sand and of humus from the decayed leaves of heather and other plants. It is only used for flower gardens, and furnishes an example of what might be called sand-and-humus soil.

“Clay is a soil which, when moistened with water and thoroughly kneaded, becomes a soft and tenacious dough, suitable for molding into any desired shape. When perfectly pure it is white, and is known as kaolin, a rare substance of which porcelain is made. Plastic clays are those that are unctuous to the touch, forming with water a yielding mass that hardens with firing. They are used in making pottery. Smectite, or fuller’s earth, is a clay of very different character, not pliable when moistened, but very absorbent of grease and hence used by fullers for cleansing cloth of the oil left on it in weaving. Ochres are clays colored either red or yellow by iron-rust. They are used in coarse painting. Red chalk belongs to this class of clays. Marl is a mixture in variable proportions of clay and limestone. According to which constituent predominates, it is called argillaceous or calcareous. Subjected to the action of air and moisture, marl becomes flaky and crumbles to dust. Marl is used in agriculture to improve the soil.

“A clay soil is quite the opposite of a sandy soil: water makes it swell and converts it into a sticky paste which clings tenaciously to farming implements. [[24]]Once wet, it is cold, that is to say it dries very slowly. A spade can only divide it into dense clods slow to crumble in the air and not fit for receiving seed. The farmer must be careful to drain off the water and break up the ground by working it before and during frosts. It is improved by mixing with it sand, coal-ashes, and lime. Wheat flourishes better in a clayey soil than in any other kind.

“Clayey soils are recognized by their vegetation. The wild plants peculiar to this kind of soil are colt’s-foot and danewort. Colt’s-foot is also called horse-foot from the shape of its leaves, the outline of which reminds one of a horse’s hoof. The leaves are white underneath. The flowers are yellow like little marigolds, and they appear at the beginning of spring before the leaves. Danewort is a kind of herbaceous elder of about half the height of a man. Its small white flowers are succeeded by berries full of a violet-red juice.” [[25]]

[[Contents]]

CHAPTER V

DIFFERENT KINDS OF SOIL

(Continued)

“Limestone is the rock from which lime is obtained. It is composed of carbonic acid and lime. To obtain the latter, the limestone is subjected to intense heat in a furnace or lime-kiln. The carbonic acid escapes, is dissipated in the air, and only the lime remains. In arable land limestone is found rather often in smaller or larger pieces, but more frequently as a fine powder which the eye can scarcely distinguish from the other constituents, especially clay. The water of rivers and other streams almost always contains a small proportion of dissolved limestone. Thence comes the thin layer of stone that accumulates little by little on the inner surface of bottles, coating the glass. Some waters contain enough of this dissolved limestone to deposit a mineral crust on objects immersed in them, as mosses and aquatic plants, and to obstruct their aqueducts. The clearest water, in which no foreign substance can be seen, absolutely none, nevertheless contains dissolved limestone, just as sweetened water contains invisible sugar. In drinking a glass of water we drink a little stone at the same time. Our body, in order to grow strong and increase in size, [[26]]needs considerable calcareous matter for the formation of bones, which are to us what its solid framework is to a building. This material, so necessary to us, is not created by us; we obtain it from our food and drink. Water plays its part in furnishing this limestone, which it furnishes also to plants; they all contain a greater or less proportion of this mineral matter.

“Calcareous soils are whitish from their chief constituent, chalk. Entirely sterile when the proportion of limestone is excessive, they are tolerably productive when clay is added. They are especially suitable for vineyards and for raising lucerne, sainfoin, and clover. Champagne and the south of France offer examples of this kind of soil. Its principal varieties are chalky soil, which is nearly sterile, containing as much as ninety-five per cent of chalk, and marly soil which is composed of clay and chalk.

“The plant-life characteristic of calcareous soils comprises the box-tree, whose compact and fine-grained wood is so esteemed by turners; the wild cornel, whose red, olive-shaped fruit is one of the best-liked autumn products that nature offers us; and the alkekengi, or winter cherry, whose yellow berries are used for coloring butter. These berries are encased in a large, gorgeously red membranous bag.

“Wood, leaves, herbage, left a long time in contact with air and moisture, undergo a slow combustion; in other words, they rot. The result of this decomposition [[27]]is a brown substance called humus or vegetable mold. The heart of old hollow willows is converted into humus; it is the same with leaves that fall from the trees and rot on the ground. Humus from the remains of earlier generations of plant-life nourishes the plant-life of to-day, and this in turn will become mold from which future plants will spring. It is in this way that vegetation is maintained in places not cultivated by man. Humus, then, is nature’s manure. Where it is allowed to form freely, vegetation never loses its vigor, using over and over again the same material, which takes alternately the two forms of plant and humus. But hay from the field is stored in the hay-loft, and the annual harvest of wheat is taken to the granary. Thus the land is robbed of the mold that would be formed naturally by the rotting of this hay and wheat; therefore we must give back to it, under some form or other, this mold that has been taken away, since otherwise the soil will become less and less productive until finally it is quite sterile. This restitution is made in the form of animal manure, which is a sort of humus produced by digestive processes instead of by natural decay.

“Humus plays a twofold part in the soil. First, it mellows the land, or in other words makes it more easily permeable by air and water. Secondly, by the slow combustion taking place in the humus there is constantly being liberated a small quantity of carbonic acid gas, which is taken up by the adjacent roots. Agriculture can succeed only in so far as the [[28]]soil contains humus. Wheat requires nearly eight per cent, oats and rye only two per cent. In poor, sandy soils, to increase the amount of vegetable mold, it is customary to plow certain green crops under, as the farmers express it; that is, the surface soil is turned over and the growing crop intended for manuring purposes is buried and left to decay in the ground. That is what is done when the plowman turns under a field of growing grass or a stretch of clover. When it is proposed to improve a piece of land by this process, it is the practice to begin by raising a crop (which will later be turned under) that derives the greater part of its nourishment from the air, since the soil in this instance cannot of itself furnish this nourishment. Among the plants satisfying these conditions are buckwheat, clover, lupine, beans, vetches, lucerne, and sainfoin.

“Soils rich in humus have for their chief constituent the brown substance that results from the decaying of leaves and other vegetable matter. Turf land stands first as rich in humus. Turf is a dark, spongy substance that forms in moist lowlands from the accumulation of vegetable refuse, especially mosses. Turf, or peat, as it is also called, is used for fuel. To turn such a soil to account, it must first be made wholesome by drainage, it must be mellowed by paring and burning and by the addition of sand and marl, and a proportion of lime must be mixed in to hasten the decomposition of all vegetable matter. Turf lands are recognized by their sphagnei, [[29]]great mosses that grow with their roots in the water; and by their flax-like sedges, from the tops of which hang beautiful tufts of down having the softness and whiteness of the finest silk.” [[30]]

[[Contents]]

CHAPTER VI

POTASH AND PHOSPHORUS

“Let us burn a plant, no matter what kind. The first effect of the heat is to produce carbon, which, mixed with other substances, constituted the plant. If combustion continues, this carbon is dissipated in the air in the form of carbonic acid gas, and there remains an earthy residue which we call ashes. Here then are two kinds of material, carbon and ashes, which without exception enter into all plant-life. The plant did not create them, did not make them out of nothing, since it is impossible to obtain something from nothing. It must, then, have derived them from some source. We shall take up before long the subject of coal and its origin, and shall find that it comes chiefly from the atmosphere, whence the leaves obtain carbonic acid gas, which they decompose under the action of the sun’s rays, retaining the carbon and throwing off the air in a condition fit for breathing. The vegetation of the entire earth thus finds its principal nutriment in the atmosphere, an inexhaustible and increasingly abundant reservoir, because the respiration of animals, putrefaction, and combustion are continually giving forth as much carbonic acid gas as the combined plant-life of the earth can consume. To maintain [[31]]the fertility of his fields, therefore, the farmer need not give a thought to the subject of carbon; with no assistance from him his growing crops find in the air all the carbonic acid gas they require. There remains for our consideration, then, the residue left after combustion, the ashes in fact, a mixture of various substances of which we will now examine the most important.

“Let us put a few handfuls of ashes to boil in a pot of water. After boiling a little while we will let the contents cool. The ashes settle to the bottom and the liquid at the top becomes clear. Well, we shall find this liquid emitting a peculiar odor, exactly like that which comes from the lye obtained by passing water through a barrel of ashes. We shall also find that it has an acrid, almost burning taste. This smell of lye, this acrid taste were not in the water at first; they come from the ashes, which have yielded a certain constituent to the water.

“Hence we see that ashes must contain at least two substances of different kinds, of which the principal one cannot dissolve in water, but settles at the bottom as an earthy deposit, while the other, forming but a very small part of the whole, dissolves easily in water and gives it its properties, especially its odor and its acrid taste.

“If we wish to obtain this latter element by itself, we can very easily do so. All that is necessary is to put the clear liquid into a pot over the fire and boil it until all the water has evaporated. There will be left a very small quantity of whitish matter resembling [[32]]table salt. But despite its appearance it is not table salt by any means; far from it, as we shall quickly discover from its unbearable taste. It is known as potash, and it is what makes lye so good for cleaning linen. Furthermore, of the various components of ashes it is the one most essential to vegetation. Every tree, every shrub, every plant, even to the smallest blade of grass, contains a certain proportion of it, sometimes larger, sometimes smaller, according to the kind of plant-life, and therefore must find it in the soil in order to thrive. Let us add that in growing plants potash is not as the action of fire leaves it after the plants have been reduced to ashes. In nature it is combined with other substances which free it from that burning acridity. In the same way carbon, when combined with other elements, loses its blackness and hardness; in fact, it is no longer common coal.

“What else is there in ashes? A short account of the matter will tell us. In 1669 there lived in Hamburg, Germany, a learned old man named Brandt, whose head was a little turned and who sought to turn common metals into gold. From old iron, rusty nails, and worn-out kettles, he hoped to produce the precious metal. But he did not succeed in his endeavors, nor was it destined that he should succeed, for the simple reason that the thing is impossible. Never is one metal changed into another. When he was about at the end of his resources he took it into his head to conceive a crowning absurdity. He imagined that in urine would be found the ingredient [[33]]capable of turning all metals into gold. Behold him, then, boiling urine, evaporating it, and cooking the disgusting sediment, first with this, then with that, until at last one evening he saw something shining in his phials. It was not gold, but something more useful: it was phosphorus, which to-day gives us fire. Don’t make fun of old Brandt and his foolish cooking: in seeking the impossible he made one of the most important discoveries. To him we owe the sulphur match, that precious source of light and fire so easily and quickly used.

“If you examine a sulphur match you will see that the inflammable tip contains two substances: sulphur, laid on to the wood, and another substance added to the sulphur. This last is phosphorus, colored with a blue, red, or brown powder, according to the caprice of the manufacturer. Phosphorus by itself is slightly yellow in color and translucent like wax. Its name means ‘light-bearer.’ When rubbed gently between the fingers in the dark, it does indeed give out a pale gleam. At the same time there is a smell of garlic; it is the odor of phosphorus. This substance is excessively inflammable: with very little heat or with slight friction against a hard surface, it catches fire. Hence its use in the manufacture of matches.

“Phosphorus is a horribly poisonous substance. By melting a little of it in grease a poison can be obtained that will destroy rats and mice. Crusts of bread are smeared with this composition and exposed in places frequented by these animals. A nibble is [[34]]enough to ensure speedy death. Hence you perceive that because of their poisonous nature matches are to be handled with extreme care. Contact with food might produce the gravest consequences.” [[35]]

[[Contents]]

CHAPTER VII

PHOSPHATES AND NITROGEN

“Phosphorus, which is a dangerous poison, as we have seen, is nevertheless found in abundance in the bodies of all animals. It occurs in the urine, whence Brandt was the first to extract it; it is found still more plentifully in the bones, and from thence it is now obtained. There is some in meat, in milk, and in cheese; also in plants, notably cereals; hence flour and bread contain it. But do not be alarmed: we shall not die of poison like the rats that have nibbled crusts smeared with grease and phosphorus.”

“But why not,” asked Emile, “if we eat it as the rats do?”

“I will try to explain,” replied his uncle. “When two or more substances are mixed together, they lose their original properties, while the new substance obtained by their combination is found to possess new properties having nothing in common with the old ones. Thus carbon, when combined with the air that we breathe, becomes an invisible gas, subtle, and unfit for breathing. In like manner lime, burning to the taste, is converted by union with carbonic acid gas into chalk, a calcareous stone void of taste. Furthermore, poisonous substances, deadly in a very [[36]]small dose, may become harmless and even enter into the composition of our food when they are combined with other substances. Thus it is with phosphorus. What, then, is united with phosphorus in the form in which it ceases to be poisonous and enters into the composition of meat and flour? That is what we will now consider.

“When phosphorus is burned it produces a thick white smoke, of which you can get some idea by striking a number of matches all at once. This white smoke with the slightest trace of humidity is reducible to an extraordinarily acid liquid called phosphoric acid. Since this compound results from the combustion of phosphorus, just as carbonic acid is the result of the combustion of carbon, it must and in fact does contain the air without which no combustion can take place. Phosphoric acid is no longer inflammable, however much it may be heated; being itself the product of combustion, it cannot burn again. But if there is no danger of its catching fire, phosphoric acid is nevertheless dangerous on account of its intense acidity, which makes it violently corrosive in its action on flesh. If mixed with lime, however, this formidable compound loses its injurious properties and is changed into a white substance without the least taste or the slightest poisonous effect. This substance is called phosphate of lime. Burnt phosphorus and lime, thus united, furnish the greater part of the mineral matter found in bones. Put a bone into the fire: the grease and juices that permeate its substance will be burnt up and the bone will [[37]]lose a part of its weight and become friable and perfectly white. Well, this bone, calcined in the fire for a long time, is composed chiefly of phosphate of lime. It contains phosphorus, the most combustible of substances, and yet is itself absolutely incombustible; it contains one of the most poisonous substances, and yet is itself quite harmless; into its composition there has entered an ingredient possessing atrocious acidity, and yet the compound itself has no taste. Similarly combined and equally harmless, phosphorus is found in meat, milk, cereals, in flour and bread.

“A cow can furnish each week about 70 liters of milk containing 460 grams of phosphate. This phosphate comes from hay, which obtains it from the soil. But as the soil contains only a moderate quantity of it, and the hay continually takes it away, the supply will at last become exhausted and the milk will become poorer and less abundant. If a kilogram of powdered bones, containing about the same quantity of phosphate as the 70 liters of milk, is spread over the pasture, it will make good the weekly loss in phosphate that the soil undergoes in the production of the cow’s milk. Hence the efficacy of powdered bones on exhausted pasture land.

“Phosphoric acid combined with other substances is found in all our agricultural products, and hence the phosphate from bones has a very marked effect on our crops. Harvests have been doubled as if by magic through the use of powdered bones. A kilogram of this powder contains enough phosphoric [[38]]acid for the growth of a hundred kilograms of wheat. Despite their great value as a fertilizer bones will never be thus used except to a limited extent, because they are not abundant enough and also because they are much in demand in various arts and manufactures. Fortunately in some localities phosphate of lime is found in certain coarse pebbles called nodules or coprolites. These precious stones are carefully collected and ground to powder in a mill. Then, in order to make the substance more soluble in damp soil, and thus better fitted for the nutrition of plants, it is sprayed with an extremely corrosive liquid called sulphuric acid or, more commonly, oil of vitriol. In this way is obtained the superphosphate of lime which manufacture gives to agriculture as one of the most powerful of fertilizers, especially for the raising of grain.

“We were wondering a little while ago what substances could be contained in the ashes of a burnt plant, and we have now found potash to be one of them. Moreover, since all vegetation must have phosphate in order to thrive, this also ought to be found in the ashes, phosphate being indestructible by heat. And, in fact, after the incineration of any vegetable matter whatever, as a bundle of hay or a handful of grain, the delicate processes of science can always recover this compound of phosphorus; and they further find lime, iron in the form of rust, the silicious component of pebbles, and divers other substances of less interest. [[39]]

“To finish this difficult but very important subject of the nutrition of plants, I must say a few words about ammonia. This word does not tell you anything since it is a new word to you. But I will make its meaning clear to you by a familiar illustration.

“You must have noticed the strong, penetrating odor prevalent in ill-kept water-closets; and you have also perceived the same odor when soiled garments are cleaned with a certain liquid that looks like clear water. Well, this odor, so pungent that it almost produces the effect of fine needles thrust up into the nostrils and brings tears to the eyes, is the odor of ammonia.

“Ammonia is an invisible gas capable of being taken up in large quantities by water, the mixture being known as aqua ammoniæ, or water of ammonia. Combined with other substances ammonia loses its pungent odor and forms compounds which are among the most effective fertilizers. These compounds furnish vegetation with one of its essential ingredients called nitrogen. By itself nitrogen is an odorless and colorless gas. In this state it forms four-fifths of the volume of ordinary air, the air we breathe. The other fifth is composed of a second gas called oxygen, also colorless and odorless. It is oxygen that our lungs demand when we breathe, and it is oxygen that is necessary when we wish to burn anything. It is this alone that plays its invaluable part in the combustion of certain substances in our blood and in the generation of natural heat; it is this that [[40]]in the process of combustion releases carbon, phosphorus, sulphur, and other combustibles, to combine with them and produce a compound known as carbonic acid gas in the case of burnt carbon, phosphoric acid in the case of phosphorus. In fact, to it belong the properties that we have until now attributed to the atmosphere as a whole. As for nitrogen, it has no other purpose in the atmosphere than to moderate by its presence the too violent energies of oxygen; it plays there the part of the water that we put into too strong wine.

“All vegetation requires nitrogen. Wheat, for example, must have it to develop the grain in the ear; peas, beans, lentils demand it in order to fill out their pods; the pasture and the hay-field need it if they are to furnish the nutriment that the sheep and the cow will transform into milk. But plants cannot take this nitrogen from the air, where it is so abundant; it must be served up to them after a certain necessary preparation. We ourselves need phosphorus, since it enters into the composition of our bones; we need carbon still more, the principal fuel used in maintaining the heat of the body. But are we to eat the charcoal that the charcoal-burner manufactures in his furnace, and the phosphorus used in the making of matches? Certainly not. The first would be a frightful mouthful, the second an atrocious poison. We must have them prepared in a suitable way, such as they are found in bread, milk, meat, fruits, vegetables. In the same manner plant-life requires nitrogen, not as it occurs in the [[41]]atmosphere, but as it exists in certain combinations, of which the most notable are the compounds of ammonia. This explains to us the highly beneficial effect of manure on our crops. Manure is composed of the bedding used in stables and the animal excrement with which it has become mixed and impregnated. Now this excrementitious matter, especially urine, yields ammonia in decomposing, as is proved by the odor arising from latrines in hot weather and so powerfully affecting the eyes and nose. Thus manure may be said to hold ammonia compounds in storage, and from them plants derive their nitrogen, as also many other ingredients.

“Let us summarize these details. In the nutrition of plants four substances are of prime importance. First, carbonic acid gas, which yields carbon, the most widely diffused of all the elements (but which we need not dwell upon here), since plants take it chiefly from the atmosphere, to which it is supplied unceasingly. After carbonic acid come potash, phosphoric acid, and nitrogen, all of which the roots extract from the soil, where it occurs in some compound or other. These are the ingredients that the soil, if it is to remain fertile, must have given back to it as fast as they are exhausted by the crops. Such is the part played by fertilizers, without which the soil becomes exhausted and ceases to produce.” [[42]]

[[Contents]]

CHAPTER VIII

VEGETATION AND THE ATMOSPHERE

“The carbonic acid gas produced simply by the breathing of the great human family amounts every year to about 160,000,000,000 cubic meters, which represents 86,270,000,000 kilograms of burnt carbon. Piled up, this carbon would form a mountain one league round at its base and between four hundred and five hundred meters high. So much carbon is required by man to maintain his natural heat. All of us together eat this mountain of carbon in our food and in the course of the year dissipate it all in the air, a breathful at a time; after which we immediately begin the dissipation of another mountain of carbon. How many mountains of carbon, then, since the world was created, must mankind have exhaled into the atmosphere!

“We must take account, too, of the animals, which, collectively, those of the land and those of the sea, use up a big mountain of combustible matter. They are much more numerous than we; they inhabit the entire globe, both continents and seas. What a quantity of carbon it must take to sustain the life of our planet! And to think that it all goes forth into the air, as a deadly gas, of which a few breaths would cause death!

“Nor is that all. Fermentation, as in grape-juice [[43]]and rising dough, and putrefaction, as in decaying manure, produce carbonic acid gas. And it needs only a light layer of manure to cause a cultivated field to give forth between one hundred and two hundred cubic meters of carbonic acid gas per day for each hectare.

“The wood, coal, and charcoal burnt in our houses, and especially the quantities consumed in the great furnaces of factories—are not they also returned to the atmosphere in the form of harmful gas? Just think of the amount of carbonic acid gas vomited into the atmosphere by a factory furnace into which coal is poured by the carload! Think also of the volcanoes, gigantic natural chimneys which in a single eruption throw up such quantities of gas that furnaces offer no comparison. It is very clear: the atmosphere is constantly receiving carbonic acid gas in torrents that defy computation. And yet animal life has nothing to fear for the present or for the future, since the atmosphere, though continually being poisoned with carbonic acid gas, is at the same time always being purged of it.

“And what is the purgative agent commissioned by Providence to maintain the salubrity of the atmosphere? It is vegetation, my friends, vegetation, which feeds on carbonic acid gas to prevent our perishing and turns it into the bread of life for our sustenance. This deadly gas, which absorbs into itself all sorts of putrefaction, is the choicest of nourishment for plant-life; and thus out of the bosom of death the blade of grass builds up new life. [[44]]

“A leaf is riddled with an infinite number of excessively minute orifices, each encircled by two lips which give it the appearance of a half-open mouth. They are called stomata. On a single leaf of the linden more than a million can be counted, but so small are they as to be quite invisible without a magnifying-glass. This picture shows you how they look under a microscope. Well, through these orifices the plant breathes, not pure air such as we breathe, but poisoned air, fatal to an animal but wholesome for a plant. It inhales through its myriads of millions of stomata the carbonic acid gas diffused through the atmosphere; it admits this gas into the inner substance of its leaves, and there, under the sun’s rays, a marvelous process follows. Stimulated by the light, the leaves operate upon the deadly gas and take from it all its carbon. They unburn (the word is not in the dictionary, more’s the pity, for it gives the right idea)—they unburn the burnt carbon, undo what combustion had done, separate the carbon from the air with which it is bound up; in a word, they decompose the carbonic acid gas.

Stomata on a Linden Leaf

“And do not think it any easy thing to unburn a burnt substance, to restore to their original condition two substances united by fire. Scientists would need [[45]]all the ingenious means and powerful drugs they possess to extract carbon from carbonic acid gas. This task, which would tax the utmost resources of the man of science, leaves accomplish noiselessly, without effort, even instantaneously, and with the sole requirement that they shall have the aid of the sun.

“But if sunlight fails, the plant can do nothing with the carbonic acid gas, the chief item in its diet. It then pines away with hunger, shoots up as if in quest of the missing sunshine, while its bark and leaves turn pale and lose their green color. Finally it dies. This sickly state induced by the absence of light is called etiolation. It is artificially produced in gardening for the purpose of obtaining tenderer vegetables and of lessening or even entirely removing the too strong and unpleasant taste of some plants. In this way some salad greens are bound with a rush so that the heart, deprived of the sun’s rays, may become tender and white; and thus, too, celery is banked up and left to whiten, since otherwise its taste would be unbearable. If we cover grass with a tile or hide a plant under a pot turned upside down, we shall after a few days of this enforced darkness find the foliage all sickly and yellow.

“When, on the other hand, the plant receives the sun’s rays without hindrance, the carbonic acid gas is decomposed in no time, the carbon and the air separate, and each resumes its original properties. Freed of its carbon, the air becomes what it was before this admixture: it becomes pure air, fit to maintain [[46]]both fire and life. In this state it is restored to the atmosphere by the stomata to be used again in combustion and respiration. It entered the plant as a fatal gas, it leaves it as a vivifying gas. It will return some day with a new charge of carbon, which it will deposit in the plant, and then, restored to purity once more, it will recommence its atmospheric round. A swarm of bees goes and comes, from the hive to the fields and from the fields to the hives, on one trip lightened and eager for booty and on the other heavily laden with honey and returning to the comb on wearied wing. In the same way air on coming to the leaves is charged with carbon from an animal’s body, a burning fire-brand, or decaying matter; it gives it to the plant and departs for a fresh supply.

“It is thus that the atmosphere preserves its salubrity despite the immense torrents of carbonic acid that are cast into it. The plant lives on deadly gas. Under the action of the sun’s light it decomposes the gas into carbon, which it keeps for building up its own substance, and breathable air, which it returns to the atmosphere. From this carbon combined with other substances come wood, sugar, starch, flour, gum, resin, oil, in fact every kind of vegetable product. Animal and plant are of mutual assistance, the animal producing carbonic acid gas, which nourishes the plant, and the plant changing this deadly gas into air fit to breathe and into food. Thus our dependence on plants is twofold: they purify the atmosphere and they give us food.” [[47]]

[[Contents]]

CHAPTER IX

LIME

To make mortar with which masonry is held in place it is customary to use lime. In a sort of trough lined with sand are placed lumps of stone having a calcined appearance, and on these stones water is poured. In a few moments the pile becomes heated to high temperature, cracks and splits and finally crumbles into dust, at the same time absorbing the water, which disappears little by little as it is taken up by the solid matter or vaporized by the heat. More water is added to reduce it all to paste, which is finally mixed with sand. The product of the mixture is mortar. Such is the process often witnessed by Emile and Jules, who are always surprised, that stone, by having water poured on to it, should become hot and turn the water into jets of steam. “Lime,” Uncle Paul explained to them, “is obtained from a widely diffused stone called limestone or, in more learned language, carbonate of lime. The process is of the simplest sort. It consists of heating the stone in kilns built in the open air in the vicinity of both limestone and fuel, so as to avoid the expense of transportation in the manufacture of a product that it is desirable to furnish at a low price. [[48]]

“A lime-kiln is about three meters high, and is lined with fire-proof brick. An opening at the bottom serves for taking out the lime when the firing has continued long enough. In filling the kiln it is the usual practice to begin by laying large pieces of limestone so as to form a sort of rude vault over the fireplace, and on this vault are piled smaller fragments until the entire cavity is filled. The fuel used may be fagots, brushwood, turf, or coal. After the firing has gone on long enough, operations are suspended and the lime is withdrawn by breaking down the vault supporting the entire mass, which crumbles and comes crowding out at the lower opening, whence it is usually removed.

“Another method still followed in some localities and of more ancient origin consists of filling the kiln with alternate layers of fuel and limestone. The whole rests on a bed of fagots that serves for starting the fire. As soon as the fire has spread throughout the mass, the opening at the top is closed with pieces of sod in order to make the combustion slower and more even.”

“Nothing could be simpler,” said Jules, “than lime-making. Now I should like to know what effect the heat of the kiln has on the limestone. How does it happen that stone turns into lime by passing through fire?”

“Limestone,” answered his uncle, “contains two different substances: first, lime, and then an invisible substance, impalpable as air itself, in fact, a gas, carbonic acid gas. The name of carbonate of lime [[49]]given to the limestone denotes precisely this combination. As it is when taken from the ground, the stone contains the two substances closely united, so incorporated indeed as no longer to have the qualities characterizing them when apart. Heat destroys this union: the lime stays in the kiln, and the carbonic acid gas is dissipated in the atmosphere with the smoke from the burnt fuel. After this liberation of the gas the lime is left in its pure state, no longer masked by the presence of another substance, but just as it is needed by the mason for making mortar.”

“Then all that the fire does,” queried Jules, “is just to break apart the limestone and drive out the carbonic acid gas that it contained?”

“What takes place in the lime-kiln,” replied his uncle, “is nothing but the separation of the lime and the gas. Now let us turn our attention to the mortar. When lime is watered, it gets very hot, swells, cracks open, and crumbles into a fine powder like flour. The heat that is generated comes from the violence with which the two substances rush together. Before absorbing water lime is called quicklime; after this absorption, which has reduced it to powder, it is called slaked lime. This slaked lime is reduced to a paste with water, and then well mixed and kneaded with sand. The result is the mortar used in laying stone and brick in order to hold the courses firmly together and give solidity to the building.

“There is one thing I advise you to note, if you have not already done so, since it will explain to you [[50]]the part played by mortar in masonry. Look at the water that for several days has covered a bed of lime slaked by the masons. You will see floating on the surface small transparent particles resembling ice. Well, these tiny fragments of crust are nothing but stone like that from which the lime was obtained; in a word, they are limestone or carbonate of lime. To make stone of that kind two substances are necessary, as I have just told you: lime and carbonic acid gas. The lime is furnished by the water, in which it must be present in solution, since the water covers a thick bed of this material; and as to the carbonic acid gas, it is furnished by the air, where it is always to be found, though in small quantities. Lime, then, has this peculiarity, that it slowly incorporates the small amount of carbonic acid gas present in the atmosphere, and so once more becomes the limestone that it was before.

“A similar process goes on in mortar: the lime takes back from the atmosphere the gas that it had lost in the heat of the lime-kiln, and little by little becomes stone again. The sand mixed with it serves to disintegrate the lime, which thus more easily absorbs the air necessary for its conversion into limestone. When the mortar has fully resumed the form of limestone the courses of masonry are so strongly bound one to another that the stones themselves sometimes break rather than give way.

“What is known as fat lime is lime that develops great heat when brought into contact with water, and also increases considerably in volume, forming with [[51]]the water a thick, cohesive paste. On the other hand, poor lime develops but little heat, disintegrates slowly, and increases scarcely any in volume. The first kind comes from nearly pure limestone and can be mixed with a large proportion of sand, thus making a great quantity of mortar. The second kind is obtained from limestone having various foreign substances and will admit of but a small admixture of sand, thus yielding less mortar than the other. Both have the property of hardening in the air by the absorption of carbonic acid gas which converts them into limestone.

“There is a third variety of lime called hydraulic lime, which has the peculiar merit of being able to harden under water. It is made from a limestone containing a certain proportion of clay. Hydraulic mortar is used for the masonry of bridges, canals, cisterns, foundations, vaults, in fact for all stone and brick work under water or in damp soil.” [[52]]

[[Contents]]

CHAPTER X

LIME IN AGRICULTURE

“To be fertile a soil must contain limestone, sand, and clay, besides the organic substances coming from humus and fertilizers. Now it may be that nature has not endowed the soil with a sufficient quantity or with any of these three constituents. Then the character of the soil must be corrected by giving it what it lacks. That is what is called improving the land. Thus a soil that is too sandy is improved by the addition of limestone and clay; one that is too compact, too clayey, is improved by adding sand and, still more, by adding limestone. Mineral substances thus added to the soil to correct it are called correctives. These substances coöperate also in the nutrition of plants, and from this point of view may be regarded as mineral fertilizers.

“One of the most valuable of correctives is lime, which is indispensable to soils lacking limestone, indispensable also to the nutrition of nearly all our cultivated vegetables. It acts in various ways. First, it energetically attacks vegetable substances, decomposing them and converting them into humus. A pile of leaves that would take long months to rot becomes in a short time a mass of humus when mixed with lime. Hence its great utility in fields overgrown [[53]]with weeds, and in newly cleared land—in short, wherever there are old stumps, piles of leaves, remnants of wood, and patches of heather, which need to be decomposed. With the help of lime all these herbaceous or woody substances are quickly converted into humus, with which the soil becomes enriched to the great advantage of future crops.

“In the second place, lime corrects or neutralizes the acidity peculiar to certain soils, as is proved by the following experiment. Let us mix some vinegar, no matter how strong, with a little lime. In a short time the smell and acid taste of the vinegar will have disappeared. Now wherever masses of vegetable refuse, such as leaves, mosses, rushes, old stumps, are undergoing decay, there are produced certain sour-tasting substances or, in other words, acids, which are invariably harmful to agriculture. This generation of acid occurs notably in turfy soils, which have an excessive acidity favorable to the growth of coarse rushes and sedges that are valueless to us, and at the same time this acid is highly injurious to all our cultivated plants. Lime, therefore, which is sure to correct this acidity, works wonders in marshy lands, damp meadows, and turfy soils. We are warned of the need of lime by the appearance of ferns, heather, sedge or reed-grass, rushes, mosses and sphagnei.

“Thirdly, when once mixed with the soil, lime speedily resumes the form it wore before passing through the lime-kiln; that is to say, it becomes limestone, but in the shape of fine powder. This return [[54]]to the limestone condition is brought about by union with the carbonic acid gas coming from the atmosphere or thrown off by the substances decaying in the ground. Under this new form lime continues to play a useful part by supplying the calcareous ingredient to soil that lacked it, and also by preventing the clay from becoming too cohesive, too impervious to air and water.

“The addition of lime to the soil should take place at the end of summer, when the ground is dry. Little heaps of quicklime, each containing about twenty kilograms, are placed at intervals of five meters and covered with a few spadefuls of earth. In a short time the moisture in the atmosphere reduces the lime to a fine powder, which is then spread evenly with a shovel and covered with earth—an operation involving no severe labor.

“Lime should never be applied with seed. Mere contact with it would burn the young shoots. Neither should it be mixed with manure before it is used, since the immediate result would be a total loss of great quantities of ammonia, thrown off in gaseous form; and ammonia, as I have explained, is one of the richest of fertilizers. Lime and manure, therefore, should be used separately.

“Soils rich in turf, clay, or granite are the ones on which lime acts most beneficially. Because of the important results attained by the use of lime, its manufacture for purely agricultural purposes by certain expeditious and effective methods is customary in many places. Thus in Mayenne, where this application [[55]]of lime has converted tracts of uncultivated clayey land into rich pastures or into wheat fields of exceptional fertility, lime is made in enormous kilns a dozen meters high and supported by the cliff that furnishes the limestone and sometimes the fuel also.

“All animal matter makes excellent fertilizer. Of this class are old woolen rags, stray bits of leather, fragments of horn, dried blood from slaughter-houses, and flesh not fit for human consumption. All these substances are rich in nitrogen and phosphates, and if mixed with farm manure they add greatly to its value. Lime furnishes us the means of utilizing one of these substances, flesh, in the best way possible.

“Dead bodies of animals, heedlessly left for dogs and crows and magpies to devour, should be cut up in pieces and then buried with a mixture of earth and quicklime. This attacks the flesh and quickly decomposes it, so that in a few months’ time there would be available a deposit of the most powerful fertilizer instead of a useless, disease-breeding carcass. As to the bones, resistant to the action of lime, they are burned to render them more friable, and then reduced to powder. This bone-dust, mixed with the fertilizer furnished by the decayed flesh, will contribute to grain-field or pasture a rich supply of phosphorus. To uses of this sort the farmer should put all horses and mules that have had to be killed, as well as all large farm animals that have died of disease.” [[56]]

[[Contents]]

CHAPTER XI

PLASTER OF PARIS

“Though less important than lime, plaster of Paris is nevertheless much used in building, especially for ceilings, molded chimney-pieces, and in the filling of cracks and cavities. It is a white powder which is made into a paste by adding water, prepared a little at a time and only as fast as needed.”

“I’ve seen them do it,” Emile interposed; “the workman takes a few handfuls of that powder out of a bag, and then he mixes it with a little water in his trough with a trowel. He scrapes the paste all together in his hand and uses it immediately, before making any more. Why don’t they mix all the plaster at once, as they do with lime when they make mortar?”

“Plaster is not all prepared beforehand for the reason that it hardens very quickly, turns to stone, and is then unfit for use. Accordingly, to have it in a suitable state of softness, it must be prepared at the moment of using.”

“And what do they make that powder of that turns to stone when it is mixed with water?”

“Plaster is made from a stone called gypsum, which, always the same as to its nature, varies much [[57]]in appearance according to its state of purity. Sometimes it is a shapeless rock, whitish and more or less grained; sometimes a fine fibrous mass with a silky luster; or, again, a substance as transparent as glass and splitting into very thin scales which show, here and there, the superb colors of the rainbow. Struck by their beauty, workmen engaged in quarrying gypsum have given the name of ‘Jesus-stone’ to these brilliant laminæ. Also, from their brilliance and their cheapness, they are called ‘donkey’s mirrors.’ In ancient times these beautiful sheets of transparent gypsum were used as window-panes.

“Impure gypsum, in the form of shapeless rock, is used for ordinary plaster, while pure gypsum, which comes in glass-like sheets or in blocks of a silky appearance, is used for fine plaster, as in all sorts of molding. The stone from which plaster is obtained occurs in abundance in several departments of France, where it forms hills and even whole mountains, as for example in the departments of the Seine, the Mouths of the Rhone, and Vaucluse. For conversion into the usual plaster of Paris this stone must be subjected to a moderate heat. To this end it is the practice to build with gypsum blocks a row of small vaults, and on these vaults to pile fragments of smaller size. Then the firing is done by burning fagots and brushwood under these vaults.”

“And is it carbonic acid gas this time, too, that is driven out by the heat, as in the manufacture of lime?” asked Jules. [[58]]

“No, my friend: gypsum does not contain any carbonic acid gas. It is made of lime, as in limestone, but united with sulphuric acid, which heat is powerless to drive out. Besides this it contains water, which forms a fifth of the total weight of the stone. This water, and nothing further, escapes under the action of heat. With this expelled the gypsum is turned to plaster.

“But this latter has a strong tendency to take on again the moisture parted with in the kiln, and thus to become once more what it was in the beginning—primitive stone. It is this peculiarity that renders gypsum suitable for plaster. Moistened in the trough, the powdery matter quickly incorporates the water that is thus restored to it, and the whole hardens into a block having the solidity of gypsum that has not yet passed through the kiln. Lime turns to stone by being permeated with carbonic acid gas, which restores it to its limestone state. Plaster becomes stone by absorbing water, which brings it back to the state of gypsum. The transformation of lime is slow, of plaster very rapid.

“As soon as it comes from the kiln plaster is ground under vertical millstones and then sifted. The powder must be kept in a very dry place, since it contracts moisture easily and then will not harden or set, as they say, when mixed with water. You will perceive clearly enough that after being more or loss impregnated with moisture plaster cannot have the same tendency to absorb the water necessary to change it into a solid mass; the substance [[59]]being already somewhat soaked will not show the same thirst when the time comes for using it. All damp and, still more, all wet plaster is of no further use.

“Statues, busts, medallions, and various other ornamental objects are made by casting with fine plaster of Paris. This is prepared from the purest gypsum, those beautiful transparent scales I told you about a little while ago. It is heated in ovens similar to those used by bakers, and cut off from contact with the burning fuel, so as to preserve its whiteness. The powder, which looks like fine flour, is mixed with water and reduced to a smooth paste, which is then poured into molds. When the plaster has set, the mold, which is in several pieces, all joined together, is taken apart and the finished cast withdrawn.” [[60]]

[[Contents]]

CHAPTER XII

PLASTER OF PARIS IN AGRICULTURE

“In agriculture plaster of Paris has by no means the importance of lime; nevertheless it produces excellent results on clover, sainfoin, and lucerne. It is used in the spring for sprinkling the young leaves when they are still damp with the morning dew. Still, foggy weather is the most favorable for this work. Plaster also acts well on rape, flax, buckwheat, and tobacco, but has no effect on cereals.

“The intelligent farmer puts plaster of Paris to still another use. In every dunghill there is always going on a slow combustion, or fermentation, giving forth ammonia in vaporous form; and this ammonia escapes into the air as a total loss, whereas it ought to be retained as far as possible in the manure, since the compounds of ammonia constitute the source whence plants obtain nitrogen. Therefore to prevent this waste, plaster is sprinkled over the dunghill. Sometimes, too, it is sprinkled over each layer of manure as the pile rises. The plaster absorbs the ammoniac vapors, gives them a little of its sulphuric acid, and converts them into a compound, sulphate of ammonia, which is proof against vaporization. Hence we say that plaster of Paris fixes [[61]]ammonia, that is to say prevents its being dissipated.

“To illustrate the fertilizing effect of plaster of Paris on lucerne, the following incident is related. Franklin, one of the chief glories of the United States of North America, aware of the great fertilizing power of plaster, wished to extend the agricultural use of this substance among his fellow-citizens; but they, clinging to old customs, would not listen to him. To convince them, Franklin spread plaster over a field of lucerne by the side of the most frequented road leading out of Philadelphia, but spread it in such a way as to form letters and words. The lucerne grew all over the field, but much taller, greener, and thicker where the plaster had been applied, so that the passers-by read in the field of lucerne these words traced in gigantic letters: ‘Plaster of Paris was applied here.’ The ingenious expedient was a great success and plaster was very soon adopted in agriculture.”

“The doubters must have been convinced,” said Jules, “on seeing those big green letters rising above the rest of the lucerne. Did not Franklin do some other remarkable things? I remember the name; I have seen it several times in books.”

“Yes,” replied his uncle, “Franklin became by his learning, one of the most remarkable men of his time. Among other things, we owe to him the invention of the lightning-conductor, that tall pointed iron rod erected on the roofs of buildings to protect them from the thunderbolt. It was he who first had the [[62]]superb audacity to evoke the lightning from the midst of the thunder-clouds, to direct it according to his wishes, and to bring it to his feet that he might study its nature. One stormy day in 1752 he went out into the country near Philadelphia in company with his young son who carried a kite made out of a silk handkerchief tied at the four corners to glass rods. A pointed piece of metal terminated the apparatus. A long hemp cord, with a shorter cord of silk tied to the lower end, was fastened to the kite, which was then sent up toward a black thundercloud. At first nothing happened to confirm the previsions of the American sage, and he was beginning to despair of success when there came a shower of rain and with it a flash of lightning. The wet cord proved a better conductor than when dry. Without thinking of the danger he ran, and transported with joy at having brought within his reach that which causes thunder, Franklin put his finger near the cord and made little spurts of fire dart out, lighted brandy from these sparks out of the sky, and only brought his perilous experiment to an end when he had fully determined the origin and nature of thunder and lightning. This was the way he studied the mystery at close quarters, discovered its nature, and finally succeeded in protecting buildings by means of a pointed iron rod.

“Benjamin Franklin was born in Boston, North America, in 1706. He was the youngest[1] of seventeen [[63]]children. Hence, as his father was a poor tallow-chandler and soap-boiler, he could not acquire at home anything beyond a knowledge of reading, writing, and arithmetic. At ten years of age he was taken from school and set to performing small tasks about the house. He cut candle-wicks and poured the tallow into the molds, waited on customers in his father’s shop, and ran errands. His work brought him in a few pence which he did not yet know how to spend judiciously. He tells us the following little story on this subject, which we may all profit by.

“ ‘One day,’ says he, ‘finding myself the possessor of a handful of coppers, I ran out to buy some toys, when a little boy of about my own age happened to pass that way with a whistle in his hand. Delighted with the sound of the whistle, I proposed to my comrade to exchange all my money for his musical instrument. To this he very willingly agreed. Elated with my purchase, which I thought very fine, I returned home, where I continued whistling to my great joy, but to the great displeasure of the ears of my family. I told them of the magnificent exchange I had just made. My brothers and sisters made fun of me, saying that for the price I had paid I might have bought dozens of such whistles at the toy-shop. Only then did it occur to me what fine things I might have bought with my money, and I began to cry with vexation. Chagrin at the exchange I had made now caused me more pain than the whistle had before given me pleasure. This little incident made an impression [[64]]on me that has never been effaced and has been of service to me on more than one occasion. Ever since, whenever I am tempted to buy some useless thing, I say to myself, “Do not pay too much for your whistle”; and so I save my money.’ ” [[65]]

[1] The author is not quite accurate here. Franklin was, as he tells us, “the youngest son, and the youngest child but two.”—Translator. [↑]

[[Contents]]

CHAPTER XIII

NATURAL FERTILIZERS—GUANO

“Plant-life finds a part of its sustenance provided by nature in the atmosphere; it finds carbonic acid gas, whence it derives the carbon it requires; but the care and ingenuity of man have to supplement these natural resources by providing fertilizers.

“One of the chief of these fertilizers, farm manure, is furnished by the bedding and excrement of animals. To obtain an excellent dressing of this sort it is customary to use for bedding, as far as possible, the straw from grain, since this, being composed of hollow stalks, is capable of holding considerable moisture. But, as in certain cases straw would hardly be able to absorb all the fluid matter, it is well to make a trench in the stable and thus carry off the excess of liquid to a reservoir outside, where another heap of straw or similar material is in readiness to receive it. Then, at a distance from all rain-spouts and gutters, and in the shade of trees, a substantial layer of clay is spread on the ground, and on this is erected the pile of manure. All around it is dug a little trench which conducts the brown liquid that oozes from the manure, and that is known [[66]]as liquid manure, into a hole large enough to admit of the use of a bucket in drawing out the liquid.

“Liquid manure is composed of the fluid matter with which the bedding is steeped, and it holds in solution a great part of the nutritive constituents of the manure. Agriculture knows no richer fertilizer. Hence care should be taken not to let it go to waste in neighboring ditches or soak into the ground. That is why the pile is placed on a layer of clay, which keeps the liquid manure from soaking into the ground where it would be wasted; and it is also the reason for digging a trench to receive this fluid matter and conduct it to the hole. When this hole is full the liquid manure is drawn out with a bucket and thrown back on to the dung-hill.

“Nor is that the whole of the story. A slow combustion will soon begin throughout the pile of manure; its mass will ferment and become heated, and as a consequence the nitrogenous constituents will decompose and will liberate ammonia, which will escape into the air and be lost if the fermentation is excessive. It is to avoid too rapid a heating that the manure-pile is placed in the shade and not under the direct rays of the sun. Moreover, the liquid manure thrown on to the heap from time to time also moderates the fermenting process.

“Compare this careful method with the practice on most farms, where the manure is heaped up without any precaution, without shelter from the sun, unprotected from the drenching rains, which wash away the soluble constituents. Think of those rivulets [[67]]of liquid manure trickling away in this direction and that, and collecting here and there in puddles of infection. See how all the inmates of the poultry-yard scratch at the heap, turning over and scattering its contents, and thus causing the ammonia to escape into the atmosphere. Can such a dung-hill be as valuable as one that is attended to properly?

“Liquid manure being the richest part of the whole pile, care should be taken not to let escape what the bedding does not absorb. It should be first diluted with water and then applied to the growing crops. When it is desired for use in non-liquid form, it should be mixed with enough earth to absorb it, and the result is an excellent fertilizer.

“In summer it is not unusual to enclose with hurdles a piece of land soon to be cultivated, and into this enclosure a flock of sheep is driven to pass the night under the care of the shepherd in his movable hut, and with the protection of trusty dogs well able to cope with any marauding wolves. The next night the flock is quartered in another spot, and so on until the entire field has thus served, a little at a time, as stable for the flock. The purpose of this procedure is to utilize the excrement, both solid and liquid, left behind by the flock. In one night a sheep can fertilize a square meter of surface. This method of fertilizing is very effective because of the complete absorption of the fluid matter by the soil.

“Off the coast of Peru in South America are several small islands which form a common rendezvous for great numbers of sea-birds. Birds that frequent [[68]]the sea are all notorious for their insatiable appetite. Constantly in search of fish, which they live on, they spend the day exploring the surface of the waters at immense distance from land. Nature has endowed them with prodigious flying power. To these indefatigable rovers an aërial promenade of some hundreds of leagues before dinner is a mere nothing. Scattered during the day in all directions in quest of prey, they reach the islets in the evening to spend the night, arriving in flocks so dense as to darken the sky. Being well fed, thanks to their foraging excursions, they cover the ground at night with a thick layer of excrement. And as this has been going on century after century ever since the world was made, these deposits, piled one on another, have at last become massive beds twenty or thirty meters thick, and so hard, so compact, that to break them it is necessary to use a pick or a petard, just as one would in quarrying stone. Workmen operate this dung mine, and vessels from all parts of the world fetch cargoes of this valuable material, which is called guano. This enormous mass of dung, which has by the lapse of ages been turned into a sort of whitish loam, gives Peru an annual revenue amounting to sixty millions of francs.

Common Gull, or Mew-gull

[[69]]

“Guano is the strongest fertilizer known to agriculture. It is scattered broadcast over the field when vegetation is starting, and for the best results a rather damp time is chosen for this work in order that the moisture may convey to the roots of the plants, by gradual infiltration, the soluble constituents of the fertilizer. The action of guano on vegetation is of the promptest, most powerful sort.” [[70]]

[[Contents]]

CHAPTER XIV

THE STALK OF THE PLANT

“The stalk is the common support of the plant’s various parts. It is called annual or herbaceous when it lives only one year, as in the potato, spinach, parsley, and all forms of vegetation that from their soft structure belong to the class of herbs. Ligneous is the name given to the stalk when, designed to live for a greater or less number of years, it is made of strong woody fibers, such as we find in the trunks of trees.

“Let us make a clean cut through any tree-trunk, that of an oak for example. We shall find it divided into three parts: in the center the pith or marrow, very slightly developed; around the marrow the wood proper; and, finally, on the outside, the bark. A closer examination shows that the wood is formed of concentric layers which are indicated in the cross-section by a series of circles having the marrow for a common center. These layers are called ligneous zones or, since one is formed every year, annual layers. During the summer there is a downward flow, throughout the tree, of a peculiar liquid, the descending sap, which constitutes the fluid nourishment of the tree. This liquid runs between the wood and the bark and becomes, little by little in its course, [[71]]on one side a layer of wood which attaches itself to the outer surface of the preceding year’s layer, and on the other side a thin sheet of bark which is added to the inner surface of the bark already formed.

“Thus each year both bark and wood form a new layer; but this added layer is applied in opposite ways in the two instances,—outside on the wood, inside on the bark. The wood thus encircled from year to year by new layers increases in age toward the center and becomes younger and younger toward the circumference, whereas the bark, lined every year with a fresh sheet, shows its youth on the inside and its age on the outside. The first buries inside the trunk its decrepit and dead layers; the second thrusts its old layers outside, where they crack and fall off in large scales. This aging process is simultaneous on the outside and in the center of the tree-trunk; but between the wood and the bark life is always at work, creating fresh accretions.

Cross Section of Tree Trunk

“Here are some experimental proofs of this annual formation of a ligneous layer. A strip of bark is removed from the trunk of a tree, and on the wood thus laid bare is fastened a thin sheet of metal. The bark is then replaced and bound with ligatures so that the wound may heal. We will suppose ten years have passed. The bark is raised again at the same place. The metal sheet is no longer visible; to find it you must bore deep into the wood. Now, [[72]]if you count the ligneous layers removed before reaching the metal sheet, you will find precisely ten, just the number of years that have passed.

“A number of observations like the following are familiar: Some foresters cut down a beech bearing on its trunk the date 1750. The same inscription was found again in the inner substance of the wood, but to reach it they had to cut through fifty-five layers on which no mark whatever appeared. If now, we add 55 to 1750 we obtain precisely the year when the tree was felled, or 1805. The inscription carved on the trunk in the year 1750 had passed through the bark and reached the layer of wood that was then outermost. Since that event fifty-five years had passed and new layers, exactly the same in number, had grown over the first.

“Thus a tree is composed of a succession of woody sheaths, the outer ones enveloping the inner. The stem or trunk contains them all; the branches, according to their age, contain more or fewer. Each one represents a single year’s growth. The woody sheath of the present year occupies the exterior of the trunk, immediately under the bark; those of former years occupy the interior, and the nearer they are to the center the older they are. The layers of future years will come one at a time and take their places over preceding layers, so that what is now the outermost layer will in its turn be found embedded in the body of the trunk.

“Of all these ligneous zones of unequal age the most important to-day is the outside one; its destruction [[73]]would cause the death of the tree, since through it the nutritive juices of the earth reach the buds, leaves, and young branches. In their time the interior layers, one by one, when they formed the surface, rendered the same service to the buds of their day; but now that these buds have become branches the inner layers have only a secondary office, or even none at all. Those nearest the outside still have some aptness for work and help the layer of the year to carry the juices from the earth to the branches. As to the innermost ones, they have lost all activity; their wood is hard, dried up, encrusted with inert matter. In their decrepitude these interior layers are incapable of service in the work of vegetation; the most they can do is by the support of their firm woody structure to give solidity to the whole. Thus the tree’s activity decreases from the outside toward the center. On the surface are youth, vigor, labor; in the center old age, ruin, repose.” [[74]]

[[Contents]]

CHAPTER XV

THE ROOT

“The stalk or trunk is the upward-growing part of the plant, and needs air and light. The root, on the contrary, is the downward-growing part, and it needs soil and darkness. The extreme ends of the root’s various subdivisions are always growing, always young, of delicate structure, and for that reason admirably fitted for imbibing, very much as a fine sponge would do, the liquids with which the soil is impregnated. Because of their facility in absorbing moisture these ever-growing tip-ends are called spongioles. The spongioles terminate the rootlets, that is to say the final subdivisions of the root, subdivisions known as root-hairs on account of their resemblance to real hair.

“The root takes various forms, which are all reducible to two fundamental types. Sometimes it consists of a main body or tap-root, which sends out branches as it bores deeper into the soil. This designation, tap-root, is a common and familiar term. Sometimes the root assumes the form of a tuft, a bunch of rootlets, simple or branching, which, springing from the same point, continue to grow at a nearly equal rate and on an equal footing as to importance. [[75]]Roots of this sort are commonly known as fibrous roots.

Roots

“As a general rule, the growth of the root keeps pace with that of the stem or trunk. Thus the oak, elm, maple, beech, and all our large trees have a vigorous, deep-growing root as anchorage for the enormous superstructure, to brace it firmly against the wind. But there is no lack of lowly herbage that has roots quite out of proportion to the other parts,—veritable tap-roots of greater size and vigor than many a plant of far greater aërial development can boast. To this class belong the mallow, carrot, and radish. Lucerne has for support to its meager foliage a root that bores two or three meters into the ground.

“An agricultural practice of supreme interest is based, at least partly, on the excessive development of certain roots. The plant is a laboratory where life converts into nutritive matter the manure from [[76]]our stables and poultry-yards. A cart-load of dung becomes at the farmer’s pleasure, after passing through one sort of plant or another, a crop of peas or beans, a basket of fruit, or a loaf of bread. Hence this fertilizer is a very precious thing which nothing can replace and which must be utilized to the very utmost. The nourishment of us all depends on it. Enriched with this fertilizer, the soil produces, we will say, a first harvest of wheat. But wheat with its bunch of short and fine roots, has drawn only upon the upper layer of fertilizing material, leaving intact all that the rain has dissolved and carried down into the lower layers. It has performed its mission admirably, it is true; it has made a clean sweep and converted into wheat all the fertilizer contained in the layer of soil accessible to its roots, so that if wheat were sown a second time no harvest would be obtained. The soil, then, is exhausted on the surface, but in its underlying strata it is still rich. Well, what crop shall we choose for the utilization of these lower strata and the production of still further supplies of food? It cannot be barley, oats, or rye, since their little fibrous roots would find nothing to glean in the surface soil after the first crop of wheat. But it will be lucerne, since this plant will send down its roots, each as thick as your finger, to the depth of one, two, or even three meters, if need be, and give back the fertilizer in the form of forage, which, with the help of the animal that feeds on it, will be converted into nutritious meat, valuable dairy products, excellent wool, or, at the very least, [[77]]animal power for draft service or other work. This succession of two or more different kinds of crops for the utmost utilization of a given area of prepared soil is called rotation of crops, of which there will be more to say later.

“Deep roots, so admirably adapted to the utilization of the lower strata of the soil, become in other circumstances a source of serious difficulty. Suppose a tree is to be transplanted. Its long tap-root will make the operation difficult and hazardous. You must dig deep, both in pulling it out and in replanting it; and then you must be careful not to injure the root, for it is all in one piece and if it does not take hold and grow the sapling will die. In this case it would be much to the tree’s advantage to have fibrous roots running down only to a slight depth; it could then be pulled up easily, and if some roots perished in the operation enough would be left intact to insure the success of the transplanting.

“This result can be obtained: it is no difficult matter to make the tree lose its tap-root and acquire, not a regular bundle of roots of even length; but a short and much ramified root that possesses the advantages of the bunch of small roots without having its shape. Thus in nurseries where young trees remain for some years before being transplanted, after two years’ growth a spade is passed under the surface of the soil to cut off the main root, which would in time become a deep tap-root. The stump that remains then branches out horizontally without going deeper. Another way is to pave the nursery [[78]]bed with tiles. The tap-root of the young tree pushes downward until it reaches this barrier, where it is straightway forced to stop growing in depth and compelled to send out lateral branches.

“The kind of root we have thus far been talking about is primordial, original; every plant has it on emerging from the seed; it appears as soon as the seed germinates. But many plants have other roots that develop at different points of the stem, replacing the original root when that dies, or at least coming to its aid if it continues to live. They are called adventitious roots, and they play a highly important part, notably in certain horticultural operations such as propagating by slips and layers, which we will talk about later.

“Besides these two operations, the object of which is to multiply the plant, it is customary to prompt the growth of adventitious roots either for the purpose of fixing the plant more firmly in the ground or in order to increase its yield. The best way to attain this result is to bank up the earth at the base of the stalk. This process is sometimes called earthing up. The buried portion soon sends out a great number of roots. Indian corn, for example, if left to itself is too poorly rooted to resist wind and rain, which beat it down. In order to give it greater stability the farmer earths up the corn. In the earth banked up at the base of the stalk bundles of adventitious roots form and furnish the plant a firmer support.

“Wheat stalks bear on their lower ends buds [[79]]which, according to circumstances, perish to the detriment of the harvest or develop into roots and promote the growth of more ears of grain. Let us suppose wheat has been sown in the autumn. In that cold and rainy season vegetation is slow, the stalk grows but little, and the various buds remain very close together almost on a level with the ground. But if they are favored by having damp soil near them, these buds send forth adventitious roots which nourish them directly and promote a fullness of growth that the ordinary root by itself could not have secured. Thus stimulated by nourishment, these buds develop into so many wheat-stalks, each one ending at a later period in an ear of grain. But if wheat is sown in the spring, its rapid growth under the influence of mild weather brings the buds too high for them to send out roots. The stalk then remains single. In the first case from one grain of wheat sown there springs a cluster of stalks producing as many ears; in the second case the harvest is reduced to its lowest terms: from one grain of wheat one stalk, one ear. Hence this development of the lower buds of cereals is of the greatest importance. To obtain it, or, in agricultural terms, to make the wheat send up suckers, the lower buds must send down adventitious roots, as they will do if they are brought into contact with the soil. To this end, shortly after germination a wooden roller is passed over the field, and this roller, without bruising the young stalks, pushes them deeper into the ground.” [[80]]

[[Contents]]

CHAPTER XVI

BUDS

“Let us take a branch of lilac or any shrub. In the angle formed by each leaf and the branch that bears it, an angle called the axil of the leaf, we shall see a little round body enveloped in brown scales. That is a bud or, as it is also named, an eye.

“Buds make their appearance at fixed points, and it is the rule for one to form in the axil of each leaf; it is also the rule for the tip-end of the branch to bear one. Those situated in the axils of the leaves are called axillary buds, and those that are found on the ends of branches, terminal buds. They are not all equally vigorous, the strongest being at the top of the branch, the weakest at the bottom. The lower leaves even shelter such small ones in their axils that only the closest scrutiny will reveal them. These diminutive buds often perish without developing unless artificially encouraged to do so. On a lilac branch it is easy to note these differences of size from bud to bud.

“Both terminal and axillary buds are divided into two classes. In developing some sprout up and produce only leaves; these are called leaf buds. When fully developed they become shoots or scions, and [[81]]finally branches. Others push upward but little and bear only flowers or leaves and flowers simultaneously. They are called flower buds, or simply buds. It is very easy to distinguish one kind from the other on our fruit-trees, the leaf buds being long and pointed, the flower buds round and thicker.

“All summer long the leaf buds grow in the axils of the leaves; they are gaining strength to go through the winter. Cold weather comes and the leaves fall, but the buds remain in their place, firmly implanted on a ledge of the bark, or a sort of little cushion, situated just above the scar left by the falling of the adjacent leaf. To withstand the rigors of cold and dampness, which would be fatal to them, winter clothing is indispensable. It consists of a warm inner envelope of flock and down, and a strong outer casing of well varnished scales. Let us examine for instance the bud of a chestnut-tree. Within we shall find a sort of wadding enswathing its delicate little leaves, while on the outside a solid cuirass of scales, arranged with the regularity of tiles on a roof, wraps it closely. Furthermore, to keep out all dampness, the separate pieces of this scale armor are coated with a resinous cement which now resembles dried varnish, but softens in the spring to let the bud open. Then the scales, no longer stuck together, separate, all sticky, and the first leaves unfold covered with a velvety red down. Nearly all buds, at the time of their spring travail, present in different degrees this stickiness resulting from the softening of their resinous coating. I will mention [[82]]especially the buds of the ash, alder, and, above all, the poplar, which when pressed between the fingers emit an abundant yellow glue, of bitter taste. This substance is diligently gathered by the bees, which use it to make their bee-glue, that is to say the cement with which they stop the fissures and rough-coat the walls of their hive before constructing the combs. Under its modest appearance the bud is a veritable masterpiece: its varnish excludes dampness; its scales protect it from harmful atmospheric influences; its lining of flock, wadding, downy red hair, keeps out the cold.

“The scales form the most important part of the bud’s winter clothing. They are nothing more nor less than tiny leaves hardened and toughened, in short so modified as to serve the purpose of protection. The leaves immediately under them and constituting the heart of the bud have the usual form. They are all small, pale, delicate, and arranged in a marvelously methodical manner so as to take up the least possible room and at the same time to be contained, all of them, despite their considerable number, within the narrow limits of their cradle. It is surprising what a quantity of material a bud can make room for under its sheath of scales in a space so small that we should find it difficult to pack away there a single hemp-seed; and yet it holds leaves by the dozen or a whole bunch of flowers. The bunch enclosed in a lilac bud numbers a hundred and more blossoms. And all this is contained in that narrow cell, with no tearing or bruising of any [[83]]portion of it. If the various parts of a bud were disconnected, one by one, if the delicate arrangement were once undone, what fingers would be clever enough to put it together again? The principal leaves lend themselves to a thousand different modes of arrangement in order to occupy the least space possible. They take in the bud the form of a cornet; or they roll themselves up in a scroll, sometimes from one edge only, sometimes from both; or they fold up lengthwise or crosswise; or they may roll up into little balls, or crumple up, or fold like a fan.” [[84]]

[[Contents]]

CHAPTER XVII

ADVENTITIOUS BUDS

“Buds such as we have been considering appear in the spring and then spend the summer in gaining strength, after which they remain stationary and as if wrapped in deep sleep all through the winter. The following spring they wake up and grow into branches or blossom into flowers. It is plainly to be seen that these dormant buds, as arboriculture calls them in its picturesque language, must, in order to withstand the summer heat and the winter’s cold, be clothed so as not to be parched by the sun or killed by the frost. They are all in fact covered with a wrapping of scales, and for that reason are called scaly buds. Buds of this class are found in the lilac, chestnut, pear, apple, cherry, poplar, and in fact nearly all the trees of our country.

But if a tree can wait and devote a whole year to the development of its buds, which are clothed in a sheath of scales because of this waiting, there are a multitude of plants that have only a limited time at their disposal: they live only a year, and hence are called annuals. Such are the potato, carrot, pumpkin, and a great many more. In a few months or days they must hastily develop their buds. These, not having to pass through the winter, are [[85]]never enveloped in protecting scales: they are naked buds. As soon as they appear they elongate, unfold their leaves, and become branches taking part in the work of the whole. Very soon, in the axils of their leaves, other buds make their appearance and behave like their predecessors; that is to say, they develop quickly into branches which in their turn produce other buds. And so on indefinitely until winter puts a stop to this scaffold of branches and kills the whole plant. Thus annuals ramify rapidly. In one year they produce several generations of branches implanted one on another, sometimes more, sometimes fewer, according to their species and their degree of vigor. Their buds, designed for immediate development, are always naked. On the contrary, those forms of vegetation that have a long life, such as trees, ramify slowly; they have only one generation of branches a year, and their buds, destined to live through the winter, are scaly.

Certain examples of plant-life have both kinds of buds. Such, for instance, are the peach-tree and the grape-vine. At the end of winter the vine-shoot bears scaly buds lined with flock, and the peach branches scaly buds coated with varnish. Both belong to the class of dormant buds: they have slept all winter in their sheaths of fur and scales. In the spring they develop into branches according to the general rule; but at the same time there appear in the axils of the leaves other buds without any protecting covering, and these develop immediately into branches. Thus the grape-vine and the peach-tree [[86]]beget two generations in one year: the first, the issue of the scaly buds that have endured the winter; the second, naked buds formed in the spring and developing very soon after their formation. The branches arising from these latter finally give birth to scaly buds, which sleep through the winter and reproduce the same order of things the following year.

“Both axillary and terminal buds are in the normal order of plant-life: they appear in all forms of vegetation that live several years. But when the plant is in danger, when by some accident the regular buds are lacking or insufficient, others spring into being here and there at haphazard, even on the root if necessary, to restore a languishing vitality and put the plant once more in a flourishing condition. These accidental buds are to the part of the plant above the ground what adventitious roots are to the part below the ground: the menace of the moment calls them into existence at any endangered point. The edges of the wound caused by the lopping off of a branch, the part of a tree-trunk constricted by a band, portions of the bark injured by contusion, these are the points where they appear by preference. They are called adventitious buds, but their structure does not differ from that of normal buds.

“Adventitious buds lend themselves to valuable uses. Suppose a number of young saplings to be planted at proper intervals in the ground. If they are then left to themselves these saplings grow each into a single trunk and form collectively a wood or forest. But it may be of advantage to replace each [[87]]of these single trunks by a group of several trunks. In that case the young plantation is cut down to the level of the ground, and around the edge of each cross-section there presently spring a number of adventitious buds which shoot up into an equal number of stems, so that each sapling that would have developed only one trunk is transformed into a stump from which start numerous sprouts or suckers, all of the same age and strength. Then instead of a wood or forest we have a growth of underbrush, or a copse. When the suckers have acquired the desired size, a fresh cutting back lays them low and induces a still denser growth of shoots by multiplying the number of wounds. It is thus that from a single stock, repeatedly cut back and as often reinvigorated by the growth of adventitious buds, a quantity of wood is obtained exceeding that produced by the free and solitary development of one tree.

“Spared by the axe, the poplar rises in a majestic obelisk of verdure. The willow, so ungraceful in appearance along the banks of our ditches, with its shapeless top bristling with shoots sticking out in all directions, is, in its natural state, a tree of rare elegance on account of the suppleness of its branches and the fineness of its foliage. Considered as a thing of beauty, it certainly has nothing to gain by man’s interference with its mode of growth. But, alas, productivity does not always go hand in hand with beauty; and if it is desired to make these two trees, the poplar and the willow, produce a great [[88]]mass of branches and fire-wood, decapitation, repeated periodically, transforms them into pollards, seamed with scars, gaping with bleeding wounds, disfigured with bruises, but at the same time contending against all this hard usage by a never-failing growth of adventitious buds which constantly replace with increasing prodigality the brushwood that has fallen victim to the axe.

“To finish the subject of adventitious buds—buds that persist in multiplying even when the parent stock languishes, and that withstand destruction until utter exhaustion has set in—let us recall for a moment certain weeds such as dog’s-tooth grass, cock-spur grass, and other grasses that are so hard to keep out of our garden paths unless we do something more than merely rake the surface of the ground. You may have taken infinite pains, we will say, to clean the paths, and have left them immaculate, or at least you think so. But you are mistaken. In a few days the grass has all come back in richer tufts than ever. The reason is plain enough now: your raking simply cut back the stems, leaving wounds that immediately covered themselves with adventitious buds, which quickly sent up new stalks. Thus, instead of destroying, you have multiplied. The only way to clear the ground of weeds is to pull them up by the roots; that done, you may consider the job well done.” [[89]]

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CHAPTER XVIII

BULBS AND BULBLETS

“After attaining the requisite degree of strength the buds of certain plants leave the parent stalk and, if we may so express it, emigrate; that is to say, they detach themselves and take root in the earth, to draw nourishment directly therefrom. Now it is evident that a bud designed for independent development cannot have precisely the structure of one destined never to leave the parent stem. To satisfy its first needs before roots capable of nourishing it have been sent down into the soil, it must of necessity have a certain prepared store of nutriment. Therefore every bud that emigrates carries a supply of food with it.

“There is cultivated in gardens a pretty little lily native to high mountains, bearing orange-colored blossoms, and known as the bulbiferous lily. Here is a piece of the stalk with its buds situated in the axils of the leaves. These buds must pass through the winter and develop the following spring. They are covered with succulent scales, very thick, tender, and fleshy, good for nourishment as well as for protection. This store of provisions makes the bud quite plump. Toward the end of summer some of these buds leave the mother plant; they fall at the [[90]]slightest wind, scatter on the ground, and are henceforth given over to their own resources. If the season is a wet one, many of them, still in place at the axils of the leaves, send out one or two little roots that hang in the air as if trying to reach the ground. Before October arrives all the buds have fallen. Then the mother stalk dies. Soon the autumn winds and rains cover the scattered buds with dead leaves and mold. Under this shelter they swell all winter from the juices of their scales, plunge their roots into the ground little by little, and, behold, in the spring each one displays its first green leaf, continues henceforth its independent growth, and finally becomes a plant like the original lily.

“The fleshy, scaly buds destined to develop independently of the mother stalk are called bulblets. No plant known to agriculture could furnish us so striking an example of bud-emigration as the bulbiferous lily; but in our kitchen gardens we have garlic, which acts in almost the same way. Take a whole head of garlic. On the outside are dry, white wrappings. Strip these off and underneath you will find large buds which can easily be detached one by one. Then come more white wrappings followed by new buds, so that the entire head is a package of alternate wrappings and buds.

“These wrappings are the dried-up lower portions of the old leaves of the plant, leaves blanched where the soil covered them, and where they still remain, and formerly green where exposed to the air, though that part is now lacking. In the axils of these leaves [[91]]buds have formed according to the general rule; only, as they are destined to develop by themselves, they have stored up supplies in their thickened scales, and that is what makes them unusually large. Split one of them lengthwise. Under a tough sheath you will find an enormous fleshy mass forming almost the whole of the bud. That is the storehouse. With such supplies of food the bud is well able to take care of itself. And, in fact, when a market-gardener wishes to raise a crop of garlic, he does not have recourse to the seed; that would take too long. He turns his attention to the buds; that is to say, he plants in the ground, one by one, the bulblets of which the heads of garlic are composed. Each of these bulblets, sustained at first by its own reserves of food, puts forth roots and leaves and becomes a complete garlic plant.

“From the bulblet to the bulb, from garlic to an onion, there is but a single step. Let us split an onion in two from top to bottom. We shall find it composed of a succession of fleshy scales compactly fitted together. In the heart of this cluster of succulent scales, which are nothing but leaves so modified as to form a food-storehouse, are found other leaves of normal shape and green color. An onion, then, is a bud provisioned for an independent life by the conversion of its outside leaves into fleshy scales; and it is called a bulb, not a bulblet, because of its size, the latter [[92]]term being the diminutive form of ‘bulb.’ Bulb and bulblet differ merely in size: the bulb is larger, the bulblet smaller, and that is all.

“Every one has noticed that an onion hanging on the wall ready at hand for the cook, is awakened to life in the course of the winter by the heat of the room, and from within its envelope of red scales puts forth a beautiful green shoot that seems to protest against the rigors of the season and reminds us of the sweet pleasures of spring. As it develops, its fleshy scales wrinkle, soften, become flabby, and finally fall off in decay to serve as fertilizer for the young plant. Sooner or later, however, its store of provision being exhausted, the shoot perishes unless placed in earth. There we have a striking example of a bud that develops independently by means of its own accumulated supplies. The leek is also a bulb, but very slender in shape. Like the onion, it consists of a cluster of lower leaf-parts sheathed one inside another. Among ornamental plants having bulbs are the lily, the tulip, and the hyacinth.” [[93]]

[[Contents]]

CHAPTER XIX

TUBERS—STARCH

“There are buds that, though called to an independent existence, do not, before separating from the mother plant, store up provisions nor thicken their scales; but the plant itself is charged with feeding them. When it is intended that the stem or branch shall itself maintain the buds it bears, then, instead of coming out into the open air where it would speedily cover itself with foliage and flowers, it remains underground and has for leaves only rudimentary scales. It grows so corpulent and deformed as to cease to bear the name of branch and to take instead that of tuber. As soon as necessary supplies have been stored up, the tuber detaches itself from the mother plant, and thenceforth the buds it bears find in it abundant nourishment for their separate existence. A tuber, then, is an underground branch swollen with nutritive material and having undeveloped scales in place of leaves, and it is also dotted here and there with buds which it must feed.

“Let us now look at a potato. What do we see on the surface? Certain small cavities or eyes; that is to say, so many buds, for these eyes develop into [[94]]branches if the potato is placed in favorable conditions. On old potatoes, late in the season, the buds are seen to send forth sprouts which need only a little sunshine to turn green and become stalks. Agriculture makes good use of this peculiarity: to propagate the plant it is customary to put into the ground, not the seeds, which would yield no harvest before the lapse of several years, but the tubers, which produce abundantly the same year. Or else the potato is cut into pieces and each piece, planted in the ground, sends up a new plant on condition that it has at least one eye; if it has none it rots without producing anything.

“Furthermore, you can see on the eyes tiny little scales, which are leaves modified to adapt them to an underground life, leaves with the same right to the name as the tough scales of an ordinary bud. Since it has leaves and buds the potato is therefore a branch. Should there remain any lingering doubts on this subject, it might be added that by earthing up the plant, that is to say by heaping soil around the stalk, the young branches thus buried can be converted into potato-bearers; and it might also be added that in rainy and cloudy seasons it is not rare to see some of the ordinary branches thicken and swell up in the open air, and thus produce potatoes more or less perfect. Accordingly the potato is to be regarded as an underground branch swollen with nourishment—in short, a tuber.

“Many other plants produce similar branches that grow under ground. In this number is the Jerusalem [[95]]artichoke, the tubers of which have buds arranged two by two on opposite swellings, from front to back and from right to left in turn, exactly as are leaves and buds on the stem.

“The potato feeds it buds on a farinaceous substance called fecula or, in less learned language, starch. It is the very material that makes the vegetable so rich in nutriment for us. We turn to our own account what the plant has stored up for its young shoots. Starch is contained in the extremely small cavities with which the flesh of the tuber is all riddled. These cavities are called cells. They are microscopic sacs made of a fine membrane and having no opening. Crammed full of starch grains and crowded one against another, they compose the fleshy substance of the potato. But these cavities are so small that a person would strain his eyes in vain in any attempt to see them in the cross-section of a potato. A magnifying glass is necessary. So minute are the cells that in a piece of potato no larger than a pin’s head there is room for dozens and dozens of them. This picture shows you, but much larger than in nature, a potato cell with the grains of starch it encloses.”

Starch Grains of Potato

“How beautifully,” exclaimed Emile, “those grains of starch are arranged in their little cubby-hole! They might be taken for a nest of eggs. And you say there are heaps and heaps of these little starch cells?” [[96]]

“Yes, my boy; in a medium-sized potato they could be counted by millions and millions.”

“It must be rather a curious sight to look at a little piece of potato through a powerful magnifying-glass.”

“It is indeed one of the most curious sights, this countless multitude of starch grains, all the same shape, all white as snow, gathered together by tens, dozens, scores, and even more, in their delicate little box-like cells.

“Let us perform an experiment not beyond our means; let us remove the starch from a potato. All we need to do is to tear open the cells in order to liberate the starch grains, and then filter them out. Watch me do it. With a kitchen grater I reduce the potato to pulp and thus tear the cells open. Now I put the pulp on a piece of linen over a large glass and pour a little water through it with one hand while with the other I keep stirring the pulp. The grains of starch from the ruptured cells are washed away by the water and carried through the meshes of the fabric, while the remnants of the cell-walls, being too large to pass through, stay behind in the filter.

“Thus I obtain a glassful of turbid water. Look at it under a bright sun. In the water a multitude of white satiny specks are falling like so much snow and piling up on the bottom. In a few moments the deposit has settled. I then throw away the clear water above it and have left a powdery substance, magnificently white, which if pressed between the [[97]]fingers creaks like fine sand. It is the starch of the potato, and is made up of such fine grains that it would take from one hundred and fifty to two hundred to equal the head of a pin in size. Nevertheless these grains, minute though they are, have a very complicated structure, each one of them being composed of a large number of tiny leaflets folded one over another. The picture I showed you just now will serve to give you an idea of these superposed leaflets that go to make, all together, a single grain. Now if some of this starch is boiled in a little water, the successive leaflets of the grain open and separate, and the whole becomes an unctuous jelly far exceeding in volume that of the starch used.”

To prove this assertion, Uncle Paul proceeded to heat in a little water the starch taken from the potato, and soon the powdery matter was reduced to a beautiful pellucid jelly. [[98]]

[[Contents]]

CHAPTER XX

USES OF STARCH

“That jelly,” remarked Jules, “looks just like the paste that I make with laundry starch. Your potato starch there in the bottom of the glass has exactly the same appearance as starch dissolved in cold water for ironing clothes.”

“That close resemblance,” replied his uncle, “is explained by the fact that potato starch and laundry starch are at bottom the same thing. Both substances are chemically known as fecula; but laundry starch is made from cereals, particularly wheat, while fecula, properly speaking, comes either from potatoes or from various grains and roots.

“Like the starch of the potato, laundry starch is in the form of superposed leaflets, but its grains are much smaller: ten thousand would hardly be enough to make a pellet the size of a pin’s head. And there are some still smaller. It would take sixty-four thousand grains of Indian corn starch to make a pin’s head or, to be more exact, to fill the inside of a cube measuring one millimeter on a side; and in the case of the beet it would take ten millions. You see that in spite of their excessive smallness, a smallness that makes them invisible to the naked eye, the starch grains of the potato are giants in comparison. [[99]]

“It is chiefly by the varying size of their microscopic grains that the starches of different kinds are distinguished from one another. In substance and structure they are all alike. Placed in warm water, their grains swell, burst, expand their leaflets, and the starch, from whatever source, is changed into a glutinous jelly.

“Starch is the food supply of plant-life. Wherever we find buds that are intended to develop by themselves, wherever we find germs, there also we shall find a supply of starch serving as a sort of food reserve. Hence this peculiar provision is met with in tubers, bulbs, bulblets, seeds, and fleshy roots. Now when these buds and germs develop, the starch becomes, in the process of vegetation, a kind of sugar which, being soluble in water, can be sent to all parts of the young plant and serve it for food.

“By certain artificial devices this same change of starch into sugar can be brought about. The simplest of these devices is the application of heat, which always enters into the preparation of farinaceous food. Let us take a few examples. A raw potato is uneatable. Boiled in water or roasted in the ashes, it is excellent. What has happened, then? Heat has converted a part of the starch into sugar, and the tuber has become a sugary farinaceous paste. The same can be said of the chestnut. Raw, it is no great delicacy, although at a pinch it can be eaten; cooked, it is worthy of all the praise we can give it. I appeal to you to back me up in this assertion. Here, then, we have another transformation of starch [[100]]into sugar by the action of heat. Beans, peas, both as hard as bullets in the dry state and of no agreeable flavor, are unmistakably sweetened by being boiled in water and having their starch acted on by heat. Our various farinaceous foods behave in the same way. Ingenuity brings into play a more powerful agent than heat alone to convert the starch into sugar. It is boiled in water and during the boiling a little sulphuric acid or oil of vitriol is added. Under the influence of this energetic fluid the starch is changed into a sugary syrup. It is of course to be understood that this syrup, as soon as it has been thus produced, is separated from the oil of vitriol which has served to make it.

“The sugar thus obtained is a soft, sticky substance, and almost as sweet as honey, but very different from ordinary sugar, which is solid and comes in beautiful white loaves.[1] It is called starch-sugar or glucose. Confectioners use it a great deal. When you crunch a sugar-plum—and I am persuaded that you do not underestimate the excellence of sugar-plums—do you know what you are eating? A composition of starch and starch-sugar. I pass over the almond in the center; that is beside the question.”

“Do you mean to say,” demanded Jules, “that a bag of sugar-plums comes from such stuff as potatoes and oil of vitriol?”

“Such is undoubtedly the origin of the delicious sugar-plum,” was the reply; “and indeed many of [[101]]the delicacies of the pastry-cook, of the confectioner, and of the manufacturer of refreshing beverages, which you believe to be sweetened with ordinary sugar, really owe their sweet taste to syrup made from starch—a much cheaper product than sugar. You see the potato furnishes something else besides the modest dishes with which it supplies our table.

“Nor is that the whole story. Starch-sugar, or glucose, is exactly the same as the sugar of ripe grapes. With potato-flour, water, and a few drops of oil of vitriol there is artificially produced, in enormous boilers, the same sugary substance that the vine produces in its bunches of grapes with the help of the sun’s rays. Now grape sugar turns to alcohol by fermenting. Glucose must undergo a similar change. And, as a matter of fact, in northern countries too cold to admit of the cultivation of the vine, alcoholic liquors are made from starch previously changed into sugar. On account of their origin these liquors go under the general name of potato-brandy. All seeds and roots rich in starch can be used in similar manufacture.