Popular Science Monthly/Volume 3/October 1873/Silk-Worms and Sericulture
|←Notes||Popular Science Monthly Volume 3 October 1873 (1873)
Silk-Worms and Sericulture
By Jean Louis Armand de Quatrefages de Bréau
|Mental Science and Sociology→|
GENTLEMEN: When your honorable director invited me to speak before you, I felt much embarrassed. I desired both to interest and instruct you, but the subjects with which I am occupied are of too abstract a nature to offer you much interest. In entering upon them I run the risk of tiring you, and, as people who are tired are little instructed, my aim would be doubly missed.
However, among the animals I have studied, there is one which, I think, will awaken your attention. I mean the silk-worm. Its history is full of serious instruction. It teaches us not to despise a being because, at first, it seems useless; it proves that creatures, in appearance the most humble, may play a part of great importance to the world; it shows us that the most useful things are often slow to attract public attention, but that sooner or later their day of justice arrives. It teaches us, consequently, not to despair when valuable ideas or practical inventions are not at first welcomed as they should be, for, though their triumph is delayed, it is not less sure.
Perhaps, also, in choosing this subject, I have yielded a little to national egotism. I was born in that province which was the first in | France to understand the importance of the silk-worm; which owes to this industry, fertilized by study and management, a prosperity rarely equalled, and which, of late cruelly smitten, bears its misfortunes with a firmness worthy of imitation.
We are to speak, then, of industry, of studious care, of perseverance, of courage; I am certain that you will be interested.
Permit me, at first, to make a supposition––what we call an hypothesis: what would you say if a traveller, coming from some distant country, or a philosopher, who had found in some old book forgotten facts, should tell you, "There exists, in a country three or four thousand leagues from here, in the south of Asia, a tree and a caterpillar. The tree produces nothing but leaves which nourish the caterpillar." To a certainty, most of you would say at first, "What of it?"
If the traveller or the man of learning should go on to say: "But this caterpillar is good for something; it produces a species of cocoon, which the inhabitants know how to spin, and which they weave into beautiful and durable fabrics. Would you not like to enter upon the manufacture?" You would infallibly reply: "Have we not wool from which to weave our winter vestments, and hemp, flax, and cotton, for our summer clothing? Why should we cultivate this caterpillar and its cocoons?"
But suppose that the traveller or philosopher, insisting, should add: "We should have to acclimate this tree and this caterpillar. The tree, it is true, bears no fruit, and we must plant thousands of them, for their leaves are to nourish the caterpillar, and it is necessary to raise these caterpillars by the millions. To this end we must build houses expressly for them, enlist and pay men to take care of them to feed them, watch them, and gather by hand the leaves on which they live. The rooms where these insects are kept must be warmed and ventilated with the greatest care. Well-paid laborers will prepare and serve their repasts, at regular hours. When the moment arrives for the animal to spin his cocoon, he must have a sort of bower of heather (Fig. 1), or branches of some other kind, properly prepared.
And then, at the last day of its life, we must, with the minutest care and the greatest pains, assure its reproduction. Would you not shrug your shoulders and say, "Who, then, is such a madman as to spend so much care and money to raise—what?—some caterpillars!"
Finally, if your interlocutor should add—"We will gather the cocoons spun by these caterpillars, and then the manufacture which spins them will arise, which will call out all the resources of mechanics. Still another new industry would employ this thread in fabricating stuffs. The value of this thread, of these tissues, would be counted by hundreds of millions for France alone; millions that would benefit agriculture, industry, commerce; the producer and the artisan, the laborer in the fields, and the laborer in towns. Our caterpillar and its products will find a place in the elaborate treatises of statesmen; and a time will come when France will think herself happy that the sovereign of a distant empire, some four thousand leagues away, had been pleased to permit her to buy in his states, and pay very dear for, the eggs of this caterpillar"—you would abruptly turn your back and say, "This man is a fool." And you would not be alone: agriculturists, manufacturers, bankers, and officials, could not find sarcasms enough for this poor dreamer.
And yet it is the dreamer who is in the right. He has not traced a picture of fancy. The caterpillar exists, and I do not exaggerate the importance of this humble insect, which plays a part so superior to what seemed to have fallen to it. It is this of which I wish to give you the history.
Let us first rapidly observe this animal, within and without. We call it a silk-worm, but I have told you it was a caterpillar. (Fig. 7.) I add that it has nothing marked in its appearance. It is larger than the caterpillars that habitually prey upon our fruit-trees, but smaller than the magnificent pearl-blue caterpillar so easy to find in the potato-field. Like all caterpillars, it is is transformed into a butterfly. To know the history of this species is to know the history of all others.
Here in these bottles are some adult silk-worms, but here also are some large pictures, where you will more easily follow the details that I shall point out, beginning with the exterior.
At one of the extremities of its long, almost cylindrical body (Fig. 7), we find the small head, provided with two jaws. These jaws do not move up and down, as in man and most animals that surround us, but laterally. All insects present the same arrangement.
The body is divided into rings, and you see some little black points placed on the side of each of these rings; these are the orifices of respiration. The air enters by these openings, and penetrates the canals that we shall presently find. ,
The silk-worm has ten pairs of feet. The three first pairs are called the true feet, or scaly feet; the five last, placed behind, are the false feet, or the membranous feet. These are destined to disappear at length.
Let us pass to the interior of the body. Here we find, at first, the digestive tube, which extends from one extremity to the other. It commences at the œsophagus, that which you call the throat. Below you remark an enormous cylindrical sac; it is the stomach, which is followed by the very short intestine. These canals, slender and tortuous, placed on the side, represent, at the same time, the liver and kidneys. This great yellow cord is the very important organ in which is secreted the silky material (Fig. 2). In proportion as the animal grows, this organ is filled with a liquid which, in passing through the spinners, the orifice of which you see, dries in the air, and forms a thread. This thread constitutes the silk.
The nervous system of the animal, placed below the digestive tube is with insects, as with all animals, of the highest importance. It is the nervous system which seems to animate all the other organs, and particularly the muscles. The latter are what we call flesh or meat. They are in reality the organs of movement, with our caterpillar as with man himself. Each of them is formed of elementary fibres that have the property of contracting and relaxing; that is to say, of shortening and lengthening under the influence of the will and of the nervous system. Upon this property depend all the movements executed by any animal whatever.
I wish you to remark, à propos of the caterpillar—of this insect that when crushed seems to be only a formless pulp—that its muscular system is admirably organized. It is superior to that of man himself, at least, in relation to the multiplicity of organs. We count in man 529 muscles; the caterpillar has 1,647, without counting those of the feet and head, which give 1,118 more.
In us, as in most animals, there exists a nourishing liquid par excellence that we know under the name of blood. This liquid, set in motion by a heart, is carried into all parts of the body by arteries, and comes back to the heart by veins. In making this circuit it finds on its route the lungs filled with air by means of respiration.
In our caterpillar we also find blood and a species of heart, but it has neither arteries nor veins. The blood is diffused throughout the body and bathes the organs in all directions. However, it ought to respire. Here step in the openings of which I have spoken. They lead to a system of ramified canals, of which the last divisions penetrate everywhere, and carry everywhere the air—that fluid essential to the existence of all living beings. In our bodies the air and blood are brought together. In insects the air seeks the blood in all parts of the body.
I have sketched for you a caterpillar when it is full grown. But you well know that living beings are not born in this state. The general law is, small at birth, growth, and death. The caterpillar passes through all these phases.
|Fig. 3.||Fig. 4.|
|Egg and First Age, lasting five days. (An age is the interval between two moultings.)||Second Age, lasting six days.|
I pass around among you some samples of what we call seeds of the silk-worm. These so-called seeds are in reality eggs. The caterpillar comes out of the egg very small; its length, at birth is about one-twentieth of an inch. Look at these samples, and you will see how
|Fig. 5.||Fig. 6.|
|Third Age, lasting six days.||Fourth Age, lasting six days.|
great is the difference of size between the worm at birth and the fullgrown specimens I have shown you. This difference is much greater than in man. A man weighs about forty times as much as the born infant; the caterpillar, when perfectly developed, is 72,000 times heavier than when it first came from the egg.
In every thing that relates to the body, there is between men and animals more resemblance than is ordinarily believed. We also come from an egg which essentially resembles all others. That this egg may become a man, it must undergo very great changes, many metamorphoses. But all these changes, all these metamorphoses occur in the bosom of the mother, as they are accomplished within the shell for the chicken. For insects in general, and consequently for the silk-worm, a part of these metamorphoses occur in the open day. Hence they have drawn the attention, excited the curiosity, and provoked for a long time the study of naturalists. Let us say a few words about them.
Scarcely is the caterpillar born than it begins to eat. It has no time to lose in gaining a volume 72,000 times greater than it had at first; so it acquits itself conscientiously of its task, and does nothing but eat, digest, and sleep. At the end of some days this devouring appetite ceases; the little worm becomes almost motionless, hangs itself by the hind-feet, raising and holding a little inclined the anterior of its body.
This repose lasts 24, 36, and even 48 hours, according to the temperature; then the dried-up skin splits open behind the head, and soon along the length of the body. The caterpillar comes out with a new skin, which is formed during this species of sleep.
This singular crisis, during which the animal changes his skin as we change our shirt, is called moultmg, when it is a question of caterpillars in general. For the silk-worm, we designate it under the name of sickness. It is, in fact, for the silk-worm, a grave period, during which it often succumbs, if its health is not perfect.
|Fig. 8.||Fig. 9.|
|Head of Silk-worm during Moulting; swollen, and skin wrinkled.||Position of Silk-worm while Moulting.—It remains at rest for from 12 to 24 hours, fasting, but begins to eat an hour after the crisis in which it escapes from the old skin.|
The silk-worms change their skin four times. After the fourth moulting comes a redoubled appetite, which permits them to attain their full size in a few days. Then other phenomena appear. The caterpillar ceases to eat, and empties itself entirely; it seems uneasy, wanders here and there, and seeks to climb. Warned by these symptoms, the breeder constructs for it with branches a cradle or bower, into which it mounts. It chooses a convenient place, hangs itself by the hind feet, and soon, through the spinner of which I have spoken (Fig. 2), we see come out a thread of silk. This is at first cast out in any direction, and forms a collection of cords destined to fix the cocoon that is to be spun. Soon the work becomes regular, and the form of the cocoon is outlined. For some hours we can see the worker performing his task across the transparent gauze with which he surrounds himself. By little and little, this gauze thickens, and grows opaque and firm; finally it becomes a cocoon like these I place before you. At the end of about 72 hours the work is done.
Once it has given out its first bit of silk, a worm in good health never stops, and the thread continues without interruption from one end to the other. You see that the cocoon is in reality a ball wound from the outside inward. The thread which forms this ball is 11 miles in length; its thickness is only 1⁄2400 of an inch. It is so light that 28 miles of it weigh only 151⁄3 grains. So that 21⁄5 lbs. of silk is more than 2,700 miles long.
Let me insist a moment on the prodigious activity of the silk-worm while weaving his cocoon. To dispose of its silk when spinning, it moves its head in all directions, and each movement is about one-sixth of an inch. As we know the length of the thread, we can calculate how many movements are made in disposing of the silk in 72 hours. We find in this way that a silk-worm makes nearly 300,000 motions in 24 hours, or 4,166 an hour, or 69 per minute. You see that our insect yields not in activity to any weaver; but we must add that it is beaten by the marvellous machines that the industry of our day has produced.
|Fig. 10.||Fig. 11.|
|Spherical Cocoon of Bombyx Mori.||Cocoon drawn in toward the Middle.|
All cocoons are not alike. There exist, in fact, different races of silk-worms, as we have different races of dogs. These differences are less obvious in the animals themselves; they are best seen in the cocoons, which may be either white, yellow, green, or gray; some are round, others oval or depressed in the middle (Figs. 10 and 11). The silk of one is very fine and very strong, that of others is coarse and easily broken. Hence their very different values.
All I have said applies to the silk-worm properly so called—to the silk-worm which feeds on the leaves of the mulberry-tree, the Bombyx mori of naturalists. But, some years since, there were introduced into France new species of caterpillars that produce cocoons, and that live upon other leaves than the mulberry. Among these new importations, the two principal ones are the yama-maï worm, which comes from Japan, and feeds upon the leaves of the oak, and the ailanthus worm. The first gives a very beautiful and very fine silk, while that of the second is dull and coarse. But the ailanthus grows very well in unproductive soils, and hence the caterpillar which it nourishes renders an important service.
But let us return to our mulberry caterpillar, or the silk-worm properly so called. We left it at the moment when it disappeared from our eyes enveloped in its cocoon. There, in its mysterious retreat, it becomes torpid once more. It now shortens itself, changes form, and submits to a fifth moulting. But the animal which emerges from the old skin is no longer a caterpillar. It is in some sort a new being; it is what we call a chrysalis. This chrysalis scarcely reminds us of the silk-worm. The body is entirely swaddled; we no longer see either head or feet (Fig. 14). The color is changed, and has become a golden yellow. Only by certain obscure movements of the posterior part do we know that it is not a dead body.
This apparent torpor in reality conceals a strange activity in all the organs and all the tissues, which ends in the transformation of the entire being.
In fifteen or seventeen days, according to the temperature, this work is accomplished, and the last crisis arrives. The skin splits on the back; the animal moults for the last time, but the creature that now appears is no longer a caterpillar or a chrysalis: it is a butterfly (Fig. 12).
Is it needful to explain the details of this wonderful metamorphosis? The body, before almost all alike, presents now three distinct regions: the head, the chest (thorax), the belly (abdomen). Wings, of which there was not the least vestige, are now developed. In compensation, the hind-feet have disappeared. The fore-feet persist, but you would not know them, they have become so slender, and a fine down covers all the parts.
In the interior, the transformation is also complete. The œsophagus (throat) is no longer a simple reversed funnel; it is a narrow, lengthened tube, with an aerial vessel attached, of which the caterpillar offers no trace. The stomach is strangely shortened. The intestine is elongated, and its different parts, that we found so difficult to distinguish, are very much changed. If we examine in detail all the organs just now indicated, even to the nervous system, we shall find modifications not less striking.
But these are not the strangest changes that have occurred. There are others which still more arrest our attention; they are those which relate to the production of a new generation.
All caterpillars are neuters—that is to say, there are no males or females among them. They have no apparatus of reproduction. These organs are developed during the period that follows the formation of the chrysalis while the animal is motionless, and seemingly dead. Marriages occur at the coming out from the cocoon, and, immediately after, the female lays her eggs, averaging about 500 (Fig. 13). This
done, she dies, the male ordinarily dying first. It is a general law for insects; the butterfly of the silk-worm does not escape it. It is even more rigorous for him than for his brethren that we see flying from flower to flower. From the moment of entering the cocoon, the silk-worm takes no nourishment. When it becomes a butterfly, and has assured the perpetuity of the species, its task is accomplished; there is nothing more but to die.
Such, briefly, is the natural history of the silk-worm. It remains to trace rapidly its industrial history.
Whence came this insect? What is its country and that of the mulberry—for the tree and the animal seem to have always travelled side by side? Every thing seems to indicate that China—Northern China—is its point of departure. Chinese annals establish the existence of industries connected with it from those remote and semi-fabulous times when the emperors of the Celestial Empire had, it is said, the head of a tiger, the body of a dragon, and the horns of cattle. They attribute to the Emperor Fo-Hi, 3,400 years before our era, the merit of employing silk in a musical instrument of his own invention. This date carries us back 5,265 years. They are said to have employed the silk of wild caterpillars, and to have spun a sort of floss. At that time they knew nothing of raising the worm or of winding the cocoon into skeins.
This double industry appears to have arisen 2,650 years before our era, or 4,515 years ago, through the efforts of an empress named Si-ling-Chi. To her is attributed the invention of silk stuffs. You will not be surprised to see that the fabrication of silks should have a woman as its inventor.
Si-ling-Chi, in creating this industry, which was to be so immensely developed, enriched her country. Her countrymen seem to have understood the extent of the benefit, and to have been not ungrateful. They placed her among their deities, under the name of Sein-Thsan, two words that, according to M. Stanislas Julien, signify the first who raised the silk-worm. And still, in our time, the empresses of China, with their maids-of-honor, on an appointed day, offer solemn sacrifices to Sien-Thsan. They lay aside their brilliant dress, renounce their sewing, their embroidery, and their habitual work, and devote themselves to raising the silk-worm. In their sphere they imitate the Emperor of China, who, on his part, descends once a year from his throne to trace a furrow with the plough.
The Chinese are an eminently practical race. No sooner did they understand that silk would be to them a source of wealth, than they strove to obtain a monopoly of it. They established guards along their frontier—true custom-house officers—with orders to prevent the going out of seeds of the mulberry or of the silk-worm. Death was pronounced against him who attempted to transport from the country these precious elements which enriched the empire. So, during more than twenty centuries, we were completely ignorant of the source of these marvellous goods—the brilliant tissues manufactured from silk. For a long time we believed them to be a sort of cotton; some supposed even that they were gathered in the fields, and were the webs of certain gigantic spiders. The price of silk continued so high that the Emperor Aurelian, after his victories in the Orient, refused his wife a silken robe, as being an object of immoderate luxury, even for a Roman empress.
A monopoly founded on a secret ought necessarily to come to an end, particularly when the secret is known by several millions of men. But, to export the industry of Si-ling-Chi, it was needful to risk life in deceiving the custom-house officer. It was a woman who undertook this fine contraband stroke. Toward the year 140 before our era, a princess of the dynasty of Han, affianced to a King of Khokan, learned that the country in which she was destined to live had neither the mulberry nor the silk-worm. To renounce the worship of Sein-Thsan, and doubtless also to do without the beautiful stuffs, so dear to the coquette, appeared to her impossible. So she did not hesitate to use the privileges of her rank to violate the laws of the empire. On approaching the frontier, the princess concealed in her hair some mul- berry-seed and eggs of the butterfly. The guards dared not put their hands on the head of a "Princess of Heaven;" eggs and seeds passed the officer without disturbance, and prospered well in Khokan, situated near the middle of Asia.
And so commenced that journey which was not to be arrested till the entire world possessed the mulberry and the silk-worm; but it was accomplished slowly and with long halts. That which had occurred in China occurred everywhere, each new state that obtained the precious seeds attempting prohibition.
The silk-worm and mulberry got to Europe in 552, under Justinian. At this time two monks of the order of St. Basil delivered to this emperor the seeds, said to have come from the heart of Asia. To smuggle them, they had taken still greater precautions than the Chinese princess, for they hollowed out their walking-sticks, and filled the interior with the precious material. The Emperor Justinian did not imitate the Asiatic potentates, but sought to propagate and extend the silk-manufacture. Morea, Sicily, and Italy, were the first European countries that accepted and cultivated the new products.
It was not till the twelfth or thirteenth century that the silk-worm penetrated into France. Louis XL planted mulberry-trees around his Chàteau of Plessis-les-Tours. Besides, he called a Calabrian named Francis to initiate the neighboring population in raising this precious insect, and developing the several industries that are connected with it. Under Henry IV., sericulture received a great impulse, thanks chiefly, perhaps, to a simple gardener of Nimes named Francois Traucat. It is always said that this nurseryman distributed throughout the neighboring country more than four million mulberry-sprouts. In enriching the country, Traucat acquired a considerable fortune; but he lost it foolishly. He had heard of treasures buried near a great castle which commanded the town of Nimes, and which is called the Castle of Magne. He wished to increase the money he had nobly and usefully gained, by this imaginary gold; he bought the great castle and neighboring ground, and dug the earth, which brought him nothing, till he ruined himself.
The minister of Louis XIV., Colbert, sought also to propagate the mulberry. Sully with reluctance had done the same, and sent trees to various parts of the kingdom, some of which were still living when I was a child. They were called by the name of this minister, and I remember to have seen two of them in my father's grounds, which no longer bore leaves, but were piously preserved as souvenirs of their origin.
To lead in the development of sericulture, a man was needed who would not hesitate to set an example, and to make considerable sacrifices. This man, I am proud to say, was a modest officer, Captain François de Carles, my grandfather. Returning from a campaign in Italy, where he had seen how much the culture of the mulberry enriched the population, he resolved to transplant this industry into the heart of Cévennes, where were his estates. He proceeded in this way: He made plantations, and, in order to extend them, he did not hesitate to uproot the chestnuts, those old nourishers of the ancient Cévennols.
To water the mulberries, he constructed ditches and aqueducts; then he forced, so to say, the peasants to take these improved lands at their own price and on their own conditions. In this way he alienated, almost all his land, and singularly diminished his fortune; but he enriched the country. The results speak too distinctly to be misunderstood. You shall judge by the figures.
The little valley where Captain Carles made his experiments, and where I was born,, belongs to the Commune of Valleraugue. At the time of which I speak, they harvested scarcely 4,400 lbs. of very poor cocoons, that sold for very little. Recently there were produced, before the malady of which I shall presently speak, 440,000 lbs. of excellent quality, valued on an average at 2⅓ or 2½ francs per pound. At this price, a million of silver money found its way each year into this little commune of not more than 4,000 inhabitants.
Let me remark that this money went not alone to the rich. The small proprietors, the day-laborers, those even who owned not the least land, had the greatest part. In fact, most of the easy proprietors did not raise their own silk-worms; they contracted for them in this way: The laborer received a certain quantity of eggs of the silk- worm on the condition of giving a fifth of the cocoons for an ounce of eggs; they received, besides, enough mulberry-leaves to nourish all the worms from these eggs, plus a certain quantity to boot. All the cocoons above this constituted the wages or gain of the raiser.
You see, we had resolved in our mountains this problem, so often encountered and still unsettled, of the association of capital and labor; and resolved it in the best possible way for both. The interest of the proprietor was, in this case, identical with that of the rearer, and reciprocally; for the success of a good workman would equally benefit both parties, and the poor workman could profit only according to his work.
Now, this labor was in reality of little account. Until after the fourth moulting, when the silk-worm is preparing to make his cocoon, the rearing of the worms can be performed by the women and children while the father pursues his ordinary occupation. Only after the fourth moult is he obliged to interrupt his work, and occupy himself, in his turn, in the gathering of leaves. The rearing ended, an industrious family—and such are not rare with us—will have, on an average, from 250 to 500 francs of profit. This bright silver, added to the resources of the year, this profit obtained without the investment of capital, seconded by the wise conduct of our mountaineer Cévennols, leads rapidly to competency. At the end of a few years, the laborer, who had nothing, possesses a little capital to buy some corner of rock, which, by his intelligent industry, he quickly transforms into fertile soil, and in his turn becomes a proprietor.
What I am telling you is not fancy. I speak of facts that have occurred under my own eyes, and that I well know. In the country, and particularly on the soil of our old mountains, people are not strangers to each other, as in our great cities. Between the gentleman and the peasant there are not the same barriers as between the citizen and the laborer in towns. When a child, I played with all my little neighbors; I knew the most secret nooks of the eight or ten houses composing the modest hamlet which bordered the place where I was born; I saluted by their names the members of all the families of the valley. And now, when I go to the country, it is always a great pleasure to visit these houses, one by one, and take by the hand those from whom I have been so long separated. But this happiness is always mingled with sorrow; the number of those I knew diminishes with each visit, and those who have come since cannot replace them for me.
Permit me to give you the history of one of these families. It occurs to me first, as it contrasted with all the others by its miserable dwelling. This was a little thatch-built cottage, standing by itself at the foot of an irregular slope of perfectly bare rocks. It consisted of a single story, with only one room, scarcely larger than one of our bedrooms; the wall, built without mortar, was any thing but regular; the roof consisted of flags of stone, retaining, as well as they were able, a mass of straw and branches. Between the rocks that supported this house and the wall, there was a little place where was kept a pig, the ordinary resource of all Cévennol house-keeping.
This cottage was occupied, when I was eleven or twelve years old, by a man with his wife and four children. The father and mother worked in the field; the eldest child, scarcely of my age, had begun to be useful, particularly in the time of gathering the mulberry-leaves; the smaller ones drove the pig along the road, where it grew and fattened, the best it could, without any expense.
After an absence of ten years, I returned to my mountains, and the first thing was to call upon my old neighbors, those of whom I have spoken among the rest. In approaching, I scarcely knew the place. The rocks that supported the house had disappeared to make way for those traversiers of which I shall tell you presently; the house had been rebuilt, it had gained a story, and was of double its former extent; its walls were laid in mortar; its roof covered with beautiful slate. The master of the house was absent, but his wife welcomed me with a glass of wine from a neat walnut table. Then she showed me, with proper pride, a room with two beds at the farther end, the first portion being devoted to the rearing of silk-worms; and, above all, the favorite article of furniture of all good Cévennol housekeeping—an immense cupboard of walnut, crammed with clothing, dresses, and raiment of all sorts. At the same time she gave me news of all the family: the eldest son was a soldier; a daughter was married; the eldest remaining children attended to the business, and, as of old, the younger ones ran about watching the pig. I clasped with pleasure the hand of this brave woman, because this competence was the fruit of good conduct, of industry, of perseverance, and of economy. And what the silk-worm did in ten years for one family it has been doing for nearly a century for the whole region of Cévennes, because among them you generally find the same elements of success.
That you may better understand me, I wish to give you some idea of these valleys. Let me sketch for you the one I know best, the one in which I was born. It is composed of ascents so steep that, when two neighboring houses are placed one above the other, the cellar of the upper one is on the same level as the garret of the lower one. There is not much earth on these declivities, and the rocks stick out everywhere. But it is, as it were, from the rocks themselves that our mountaineers make their mulberry-plantations. They proceed in this way: They first break up the rocks, and with the larger
stones so obtained they raise a wall; then, with the smaller pieces, they fill up the interval between the wall and the mountain. This done, they bring upon their backs, from the bottom of the valley, soil and manure enough entirely to fill the space. This is what is called a traversier, and it is in this soil that most of the mulberry-trees are planted. I have seen a bridge built across a mountain-stream expressly to give foothold for two or three of these precious trees. To pay for all this preparation the produce should be very great. The following figures give the average value of ground planted to mulberries for 20 years:
|Traversiers not watered||1 acre,||9,800||francs.|
|Fields watered||1 acre,||12,000||"|
|Meadows planted with mulberries||1 acre,||12,400||"|
and even then the money yielded five per cent. This price, which some would not believe when I told them, has been officially confirmed by M. de Lavergne, in his remarkable writings upon French agriculture. This value of land, and the way it has been obtained, explain the nature of our country's wealth. With the exception of some families recently enriched by the silk-manufacture and the silk-trade, the level of this wealth, although very high, is more of the nature of general competence than of great fortunes. Industry and economy have produced general well-being, without the growth of offensive differences. I cannot say how it is now, but in my childhood there were no paupers in our commune, except two infirm people who were supported in their misfortunes by voluntary aid.
These striking results could not fail to affect the neighboring country. This example of the culture of the mulberry was imitated throughout the south of France, and adopted more or less in other departments. You can judge of the progress made in this culture by the following figures, giving the quantity of cocoons produced annually:
These 56,000,000 lbs. of cocoons sold at from 2⅓ to 2½ francs per lb., representing a value of about 130,000,000 francs. Now, these millions all went to agriculture, to the first producer; and so they added to the national wealth at its most vital source. If this progress had continued, in a few years we should have been able to supply our own manufactures, and relieve ourselves of the tribute of 60 or 65,000,000 francs that we pay to foreign countries. But, unhappily, at the moment when this culture was most prosperous, when mulberry-plantations were springing up on all sides, fed by the nurseries which were each day more numerous, all this prosperity disappeared before the terrible scourge to which I alluded in the beginning of my discourse.
Like all our domestic animals, the silk-worm is subject to various maladies. One, called the muscardine, that for a long time was the terror of breeders, is caused by a species of mould or microscopic mushroom. This mushroom invades the interior of the body of the insect. After affecting all the tissues, this vegetal parasite sometimes suddenly appears upon the outside of the body in the form of a white powder. Each grain of this powder, falling upon a silk-worm, plants the seed of this formidable mushroom, the ravages of which will destroy all the worms of a rearing-chamber in a few hours. Happily, science has found the means of killing these seeds, and of completely disinfecting the locality. At the very moment when this victory was announced, another yet more terrible scourge, the pébrine, appeared. The muscardine caused isolated disaster; it had never been so wide-spread as seriously to injure the general business. Not so this other
malady. It is a true epidemic, which attacks life at its very source in an inexplicable fashion. It is a pestilence like the cholera. Under the influence of this scourge, the chambers of the silk-worm no longer thrive; most of the worms die without producing silk. Those that survive as butterflies give infected eggs, and the next generation is worse than the first. To get healthy eggs, we had to go to the neighboring countries; but other countries have been invaded in their turn. To-day we have to get them in Japan. Even when the egg is healthy, the epidemic bears equally on its product; a great part of the worms always succumb, and when the breeder gets half a crop he is very happy. Upon the whole, the great majority of breeders have worked at a loss since the invasion of this disease.
You understand the consequences of such a state of things, continued since 1849. The people make nothing; they lose, and yet they have to live and cultivate their ground. In this business the profits melt away rapidly, and particularly where the mulberry was the only crop, as at Cévennes, misery has taken the place of comfort. Those who once called themselves rich are to-day scarcely able to get food to eat. Those who used to hire day-laborers to gather their harvest have become day-laborers, and the laborers of former times have emigrated. This will give you an idea of the extremities to which they are reduced, for to uproot a mountaineer of Cévennes he must be dying of hunger.
To escape a fatality so heavy, these people have displayed perseverance and courage of the highest kind. They have undertaken distant journeys to get non-infected eggs. More than one has not come back from these journeys, where it was needful to struggle against great fatigue in inhospitable countries. Although they fell not on a field of battle, struck by ball or bullet, they were true soldiers; and, although they did not carry arms, they died in the service of the country.
|Fig. 18.||Fig. 19.|
|Square Net.||Lozenge-shaped Net.|
|Nets used to separate the worms from their faded and withered leaves. Fresh leaves are spread on these nets, and the worms leave the old food to get on to the new leaves.|
During seventeen years this exhaustion has been most aggravated in places chiefly devoted to sericulture. But, if these local sufferings merit all our sympathy, their general consequences still more demand our attention. Confidence in the culture of the silk-worm has diminished wherever it was not the exclusive occupation. Where other crops could replace it, that of the mulberry was easily discouraged. In many countries they have destroyed the tree so lately known as the tree of gold.As the foregoing interesting discourse was delivered in 1866, the following statement of Prof. Huxley regarding the pébrine malady, made in 1870, in his address before the British Association, will be interesting.—[Editor.
"The Italian naturalist, Filippi, discovered, in the blood of silkworms affected by this strange disease, pébrine, a multitude of cylindrical corpuscles, each of about 1/6000 of an inch long. These have been carefully studied by Lebert, and named by him Panhistophyton; for the reason that, in subjects in which the disease is strongly developed, the corpuscles swarm in every tissue and organ of the body, and even pass into the undeveloped eggs of the female moth. The French Government, alarmed by the continued ravages of the malady and the inefficiency of the remedies which had been suggested, dispatched M. Pasteur to study it, and the question has received its final settlement. It is now certain that this devastating, cholera-like pébrine is the effect of the growth and multiplication of the Panhistophyton in the silkworm. It is contagious and infectious, because the corpuscles of the Panhistophyton pass away from the bodies of the diseased caterpillars, directly or indirectly, to the alimentary canal of healthy silk-worms in their neighborhood; it is hereditary, because the corpuscles enter into the egg. There is not a single one of all the apparently capricious and unaccountable phenomena presented by the pébrine, but has received its explanation from the fact that the disease is the result of the presence of the microscopic organism Panhistophyton. M. Pasteur has devised a method of extirpating the disease, which has proved to be completely successful when properly carried out."
- A lecture delivered at the Imperial Asylum at Vincennes.