Fig. 210.—Silkworm Moth (Bombyx mori), female.Before laying her eggs, the female looks out for a place suitable for this purpose. When she has found this place, she ejects an egg covered with a viscous liquid, which causes it to adhere to the body upon which it falls. Very soon she lays a second egg by the side of the first, then a third by the side of the second, and so on. She very rarely piles them up on each other. The laying lasts about three days; the number of eggs is from 300 to 700 for each female. These eggs are generally tentacular and flattened towards the centre. At the moment at which they are laid they are of a bright yellow. In a week they become brown. The colour changes then to a reddish grey; lastly it becomes of a slaty grey, remaining this colour during the autumn, winter, and a great part of the spring. Then as the temperature rises, the colour of the eggs passes successively through bluish, violet, ashy, and yellowish shades. And, lastly, they become more and more whitish every day as the hatching time approaches.If looked at closely, one remarks a black spot and a brownish crescent extending along the circumference. The black spot is the head of the worm, which closely touches the shell; the crescent is the body, which is already covered with little hairs. When it leaves the egg, the silkworm gnaws through the shell on its side, never on its flat surface. When the opening is large enough, it breaks out through it, head foremost, and immediately fixes a thread of silk to any object it can reach, no doubt in order to prevent itself from falling. Sometimes the opening is too small to allow of the head passing out, and the larvais forced to come out backwards, that is to say, tail foremost. At times, not being able to get its head free, the poor animal very soon dies of fatigue and hunger.VI.—A Silkworm rearing Establishment.VI.—A Silkworm rearing Establishment.We will now give a summary of the rearing of the silkworm, that is to say, of the attention which must be paid to this insect that it may construct its cocoon advantageously. We will call to our aid in this very rapid summary the works or notices of MM. Robinet, Guérin-Méneville, Eugène Robert, and Louis Leclerc, and we must not forget the excellent and classical Dandolo.[63]When it is desired to rear silkworms—magnans, as they were called in old French, and as they are still called in the patois of Languedoc—the first thing to do is to obtain good eggs, goodgrain, to use the technical word, and then to choose suitable premises. The essential, the fundamental point, in the rearing, is to possess premises in which the air is easily renewed. The worms should have as much air as possible given to them without ever being allowed to be chilled. There is no better means of attaining this end than by keeping a constant open fire in a room, and by letting air into the room from another chamber which separates it from the open air. One has, in this way, the best workroom for a small rearing.In the workshop are arranged racks, by the aid of which are placed, at the distance of 50 centimètres from each other, frames made of reeds. These frames, orcanisses, as they are called in the Cévennes, may be from 1 mètre to 1¾ mètres in breadth. They should be placed in such a manner that one can easily pass round them to place and remove the worms, and to distribute their leaves to them uniformly. They should be protected by a small border of a few centimètres in height, to prevent the worms from falling. And lastly, they should be covered at the bottom with large sheets of paper. (Plate VI.) A provident silkworm-rearer has always at his disposal a cellar or cool room, so as to be able to stow away his leaves as soon as they are brought in from the country.What we have just said applies especially to a small rearing. In large establishments, or even those of second-rate importance, everything is in advance of this, and mathematically regulated: aspect and arrangement of rooms, furniture of these rooms, warming, ventilation,&c. So, for a rearing house for 300 grammes of eggs, the building should be constructed in such a manner that its front and back look east and west, to avoid any inequality in the heat derived from the sun. It ought to consist of a ground-floor, a very lofty first-floor, and of a rather low roof. The ground-floor comprises the chamber of incubation, the store-room for leaves, and the air-chamber with the grate intended for warmth and ventilation. The first-floor constitutes the rearing-room properly so called.But let us leave these grand industrial establishments, to return to our rearing houses on a small scale, such as are found among the peasants of the Cévennes. They generally receive the silkworms' eggs before the end of the winter. In order to preserve them till the hatching season, they are placed in thin layers, in a piece of folded woollen stuff, which must be hung up in a cool, but not a damp place, exposed to the north. As soon as the buds of the mulberry tree begin to be partially open, they proceed to the incubation of the eggs. They are spread out on sheets of paper, in very thin layers, placed on a table in a room having a southern aspect, and left thus during three or four days, taking care to prevent the rays of the sun from touching them. It is necessary also, from time to time, to open the windows. After three or four days, the fire is lighted, taking care not to have more heat than 13° Centigrade round about the table which supports the eggs, and which should be placed as far as possible from the fire. Each day the room is warmed a little more, in such a way that the temperature is raised 1° to 2° a day, until 25° Centigrade of heat have been attained, at which temperature it is to be maintained when the eggs have reached the last stage, and till the hatching is terminated. On the first day few worms are hatched; but the hatching of the second day is very abundant, as also that of the third. Of these newly-born worms two divisions are made, separated by an interval of twenty-four hours. The worms which are born afterwards are thrown away, unless they are so abundant that they can be made a third batch of, which is to be mixed up with the second at the period of the moult.In the large rearing houses there is a special chamber for the incubation. Various simple, convenient, cheap apparatuses, whose main object is to create a permanent warm and damp atmosphere, whose degree of heat can be regulated at will, have been proposed. M. Louis Leclerc, in his pamphlet entitled "Petite Magnanerie," has given a description and drawing of a little box which is very useful for facilitating the hatching of eggs. We refer those of our readers who wish for further information on the subject to that work. Assoon as the worms are hatched, the eggs are covered with net, and over this are placed mulberry boughs, covered with tender leaves, on which all the little worms congregate. They are then lifted up with a hook made of thin wire, and the worms are placed on a table covered with paper, leaving a proper space between each. They are given, as their first meal, tender leaves cut into little pieces with a knife. These are the operations gone through for the two raisings of worms on the second and third day of the hatching. During this first age they give them from six to eight meals a day, taking care to distribute their food to them as equally as possible. The first meal is given at five o'clock in the morning; the last at eleven or twelve o'clock at night.When the moult is approaching, the young ones are made to climb on to boughs having tender leaves, so that they can be moved to litters as thin and clean as possible, and there sleep in a good state of health. When the mass of worms is well awake again, the next thing to do is to take them off the litter on which they moulted, and to give them food. If this problem were proposed to a person strange to the operation which is now occupying our attention—to separate the worms from the faded and withered food upon which they are reposing, without touching them—he would certainly be very much at a loss what to answer. The solution of this problem presented for a long time great difficulties, and occasioned numerous reverses in the rearing. Now-a-days, thanks to the employment of a net, thedélitement, or taking them off their bed, has become an easy operation.Over the worms, placed on a table, is spread a net, the meshes of which are broad enough to allow them to pass through. On this net are spread the leaves which are to compose a meal. The worms immediately leave the old food, and get on to the new leaves. They then lift the litter with the worms, and throw away the old leaves, now unoccupied, clean the table, and replace the net with the worms. At the nextdélitementthe first net is found under the litter. Figs.211and212represent two forms of these nets made of thread.Thread nets, which were of great use, have been supplanted lately, with great advantage, by paper ones, which were invented by M. Eugène Robert. These are leaves of paper, of a peculiar manufacture, pierced with holes proportioned to the size of the worms which are to pass through them. The paper net can be used advantageously also for separating the worms that are too near together, or, as they say, for thedédoublement. Formerly, thedélitementand thedédoublementwere done by hand—a tedious work, and one that presented serious disadvantages. Now-a-days, as we have seen, the worms themselves perform these two perilous operations.At the second age they still cut the leaves for the worms, but into larger pieces, and proportioned to their size. During the day the temperature of the room ought to be kept to 21° Centigrade, but it may be lowered by 1° or 2° during the night. Towards the end of this age they have only four meals. When the worms are on the point of going to sleep, their meals are decreased.Fig. 211.—Lozenge-shaped net.Fig. 211.—Lozenge-shaped net.Fig. 212.—Square net.During the third age the number of the meals is kept to four, the first being given towards five o'clock in the morning, and the last between ten and eleven o'clock at night. The leaf is cut into much larger pieces, and distributed as equally as possible. Thedélitementand thedédoublementare proceeded with as in the preceding age. One begins to find pretty often during this period of the life of worms, someluisettes—that is to say, worms which have not strength enough to moult. They are larger than those just woke up, and that have not as yet eaten, and are shiny. They must be carefully removed, for they will not be long before they die, and infect the air of the room.During the fourth age they no longer cut the leaves, but give them a great deal more at once. The result is that the litters increase in thickness, and that thedélitementmust be performed oftener; for the rest, four meals are always necessary. Manyluisettesmay be seen during the fourth age. The moult which follows the fourth age is the most critical phase in the life of the silkworm. During their sleep they are a prey to acute suffering, and are plunged into a stateof lethargy which resembles death. The dryest and cleanest litters diffuse very soon a sickly smell. This moult lasts from thirty-six to forty-eight hours. During this time the room should be kept to at least 22° Centigrade.When they awake out of this last sleep the attendant should continually be on his guard, as it is then that diseases break out. The worms suffering from these different diseases have received different names. There are besides theluisettesthearpians—that is to say, worms that have exhausted all their energy in the work of the last moult, and have not even strength to eat—theyellow, orfatworms, which are swollen, of a yellowish colour, and which very easily die; theflatsormous, the soft or indolent ones which, after having eaten a great deal and become very fat, die miserably, and enter into a state of putrefaction. And lastly, it is at this age that themuscardine, which hardly shows itself at any other age of the insect, appears with great intensity.Themuscardineis a terrible scourge to the rearers of silkworms. The losses which result from this disease in France are estimated at at least one-sixth of the profits. No particular symptom allows of our recognising the existence of this disease in worms which, however, contain its germ; only, the worm, which has eaten up to that time as usual, appears almost in a moment to change to a duller white; its movements become slower, it becomes soft, and is not long before it dies. Seven or eight days after its death it becomes reddish and completely rigid. Twenty four hours afterwards a white efflorescence shows itself round the head and rings, and soon after the whole body becomes floury. This flour is a fungus calledBotrytis bassiana, of which themyceliumdevelops itself in the fatty tissue of the caterpillar, attacks the intestines, and fructifies on the exterior. This fungus has been considered as the immediate cause of themuscardine, and has been also regarded as the last symptom or end of the disease. The communication of the disease by contagion has alternately been admitted and denied. As its true cause, and any efficacious means of opposing it, are still unknown, the breeders of silkworms must be content to apply—so as to prevent or struggle against this dreadful scourge—the precepts of hygiene: good ventilation, excessive cleanliness, frequentdélitements, and good food properly prepared.After themuscardine, we must mention another epidemic disease still more terrible, thegattine. This disease shows itself from the very beginning of the rearing, and increases in intensity at each age, so that the number of worms able to enter regularly into the moultbecomes smaller and smaller. We are still in a state of utter ignorance as to the cause of this last affection, which has occasioned, for the last ten years, incalculable losses in the rearing houses, which threatens the silkworm with complete destruction, and which in the meanwhile has ruined the unfortunate countries of the Cévennes, the principal seat of sericulture in France.During the fifth age, the worms become large so quickly that on the fifth or sixth day they are obliged to be moved away from each other on the litter. Thedélitementmust be made every two days, or indeed, every day now, on account of the enormous amount of the excrement; and, at the same time, a good ventilation must be constantly maintained. The temperature of the room should now be kept to 24°, without ever exceeding this degree of heat. When it is perceived that the worms wish to ascend, ormount, there are placed on the tables, at certain distances from each other, little sprigs of heather or very dry branches of light wood.Fig. 213.—Sprigs of heather arranged so that Silkworms may mount into them.When the worms begin to mount into the heather, one mustencabaner—that is to say, form with these branches little hedges, curved back like a hut or cradle, the openings of which are, on an average, seventeen inches or so (Fig. 213). At the expiration of twenty-four hours all the good worms have mounted. The laggards who remain under thecabanesare taken off by hand, and placed on a table, which is immediatelyencabanea.The cocoons spun on these branches of heather ought to be large, heavy, and well-shaped. The good cocoons are regular; their ends are rounded and not pierced; and they are hard, especially at their extremities, and have a fine grain. They are cylindrical. The best are drawn in towards the middle, or have a concavity on either side of it (Fig. 215). Every one knows that there are white and yellow cocoons. They are the produce of different races of worms.Commerce recognises two kinds of white silk: thefirst whiteand thesecond white. The silk of thefirst whiteis produced by the raceSina, the cocoons of which are of a perfect and azured white. They produce the most beautiful and most precious silk, and serve for the fabrication of light and delicate coloured tissues. The silk of thesecond whiteis furnished by two races: theEspagnoletand theRoquemaure.Fig. 214.—Spherical cocoon of the Bombyx mori.Fig. 215.—Cocoon of Bombyx mori, drawn in towards the middle.Fig. 214.—Spherical cocoonof the Bombyx mori.Fig. 215.—Cocoon of Bombyx mori,drawn in towards the middle.The races that produce yellow cocoons are more numerous than the white ones. The yellow races are divided into three groups: those that have small, middle-sized, or large cocoons. The first and second are stronger, and more esteemed than the last.The greater number of the races of silkworms have, let us here mention, white and yellow cocoons; there are some, however, whose cocoons are of a greenish white, or even quite green, or of a reddish green. One race, raised in Tuscany, near Pistoia, has cocoons of a pale rose colour; and, lastly, mention has been made of cocoons of a purple colour.Fig. 216.—Larva, pupa, cocoon, and moth of Bombyx mori.Fig. 216.—Larva, pupa, cocoon, and moth of Bombyx mori.When the cocoons are completed, the people in charge of the rearing establishments separate them from the heather and sell them to the silk-spinners. But they must manage to get these cocoons into a state in which they will remain entire during a long time. They must, in other words, kill the chrysalis, to prevent the cocoons being pierced by the moth. To kill the chrysalis so as to prevent thedevelopment of the imago is an operation which is called theétouffage, or stifling.Fig. 217.—Apparatus for stifling the chrysalides in the cocoons.To effect this stifling, the cocoons are exposed to a high temperature. Formerly, in the Cévennes, the cocoons were placed in abaker's oven, heated for baking bread. But they ran the risk thus of being burnt, or of a certain number of chrysalides remaining alive. Now, to kill the chrysalides, they make use of steam at 100°, produced by water boiling in a vessel, and which passes through wicker baskets filled with cocoons.The rearer must also take care at the time he gathers them, to separate the cocoons which are to provide eggs for the next year. As the female cocoons are heavier than the male cocoons, they are easily separated by weighing them in a pair of scales.To obtain the eggs, or grain, the cocoons are fixed on sheets of brown paper, covered with a slight coating of paste made of flour. They are arranged in such a manner that the moths shall find no obstacle when they come out of them, head foremost; and, moreover, so that they may be able to reach with their legs the cocoon which is opposite them, so as to hang on to it, and to facilitate their exit from their own cocoon (Fig. 218). The male and female cocoons are pasted on separate sheets.Fig. 218.—Sheet of paper with rows of cocoons prepared for the exit of the moths destined for laying eggs.Fig. 218.—Sheet of paper with rows of cocoons prepared for the exit of the moths destined for laying eggs.Fig. 219.—Sheets of paper stuck into screens, and inclined for the reception of moths.Fig. 219.—Sheets of paper stuck into screens, and inclined for the reception of moths.It is from fifteen to twenty days after themontée, ormounting, and when the temperature of the rooms has been kept between 20° and 25°, that the moths begin to be hatched. As they appear, they are seized by the wings and placed on cloths stretched out for the purpose, where they are left for about an hour, till their wings have fallen flat on their bodies. As soon as they have evacuated a red liquor, the males and females, which up to that time have been apart, are put together.They then stick sheets of paper on to screens, putting from twenty-five to thirty females on each sheet (Fig. 219). It is here the moths lay their eggs. The sheets of paper, covered with eggs, are then hung on wires, at a small distance from the ceiling of a roomhaving a northern aspect, which is never warmed. They remain thus, exposed to all variations of temperature, till the return of the warm weather. We will say a few words, to bring this subject to an end, on the winding of cocoons and the spinning of silk.The winding of cocoons is an operation which at first sight appears very simple, but which is in reality a difficult and delicate process. It requires unremitting attention, great experience, and a delicacy of touch which can only be found in the fingers of woman, or rather, in the fingers of certain women.The woman who is spinning, stands before a sort of loom which is calledtour(Fig. 220). Under her hand is a copper containing water, which she heats to the required degree by opening the tap of a tube, which brings a current of steam. She plunges the cocoons into the hot water, and moves them about in it, to soften the gummy substance which sticks the silken threads of the cocoon together. Then she beats them, with a light hand, with a small birch-broom. The threads of the cocoons get caught in the extremities of the twigs of which the little broom is made, and the workwoman seizes with her fingers the bundle of threads, and shakes them about till she perceives that they are all single, and in a fit state to be joined together.Fig. 220.—Silk-winding Establishment.Fig. 220.—Silk-winding Establishment.Let us suppose that it is wished now to make up abrin, or staple, by uniting together the ends of five cocoons. She chooses five ends in the mass, makes of these a bundle, and introduces it into the hole of afilière. She makes two staples (brins) at once, one on her right, the other on her left hand. She then brings them together, she crosses them, rolls them, and twists them, the one on the other, several times; after which, she separates them from above and keeps them well apart, making each of them pass into a hook at a distance, from which they are going to twist round into a hank, separately, on a wheel. The two threads thus twisted are drawn close together, compressed, and become one, getting round by rolling on each other, and being kept in continual motion, drawn out as they are by the rapid motion of the wheel.The difficulty which the emptying the cocoon of its silk thread presents, makes us understand what difficulties those manufacturers must have met with who have lately attempted to extract from the stalks of mulberry leaves a sort of silk. We will enter into no details of the attempts which have been made to accomplish this object in our time, attempts which have, however, been crowned with no success whatever. We will confine ourselves to reminding the reader that these attempts are far from being of recent origination, since they date back to as far as Olivier de Serres, the father of French sericulture.In a little work published by Olivier de Serres, in 1603, under the title ofCueillette de la Soie, "The Gathering of Silk," we find a memoir entitled:La second richesse du mûrier, qui se trouve en son escorce, pour en faire des toiles de toute sorte, non moins utile que la soie provenant d'icelui, "The second wealth of the mulberry tree which is found in its bark, how to make of it cloth of all sorts, not less useful than the silk derived from this tree." Olivier de Serres proves in this memoir that the second bark, orliber, of the mulberry tree contains a fibre capable of replacing hemp or flax, and he describes the processes by which this may be obtained. The processes which had been proposed by Olivier de Serres in 1603, were resumed in the Cévennes a dozen years ago by M. Duponchel on the one hand, and on the other by M. Cabanis,[64]who operated on the bark instead of taking the whole of the wood of the mulberry tree. But none of these attempts have given any good results up to the present moment.The various diseases which for the last fifteen years have been so fatal to the mulberry silkworm, have suggested the idea of acclimatising in Europe other silk-producing Bombyces, if not with the view of superseding, at least as auxiliaries to the mulberry species. The genusAttacushas furnished these auxiliaries. Among the species which have, in this respect, the greatest claims to our attention, we must place in the first rank those which feed upon the leaves of the oak tree. Indeed, the trees which can be made use of for their cultivation are very numerous in Europe, and, moreover, the silk produced by these worms appears to possess superior qualities.There are three oak-feeding species of the genusAttacus. They areYama-Maï,Pernyi, andMylitta.Fig. 221.—Larva of Attacus (Bombyx) Yama-Maï.Fig. 221.—Larva of Attacus (Bombyx) Yama-Maï.The silk ofYama-Maïis as bright as that of the mulberry silkworm, but a little less fine and strong, and occupies the first rank after it. If we could succeed in acclimatising this species it would supply any deficiency there might be in our crops of ordinary silk.The eggs of theAttacus Yama-Maïwere brought from Japan—where this worm is reared—conjointly with the mulberry silkworm, in 1862. The larvæ hatched at Paris, in 1863, were green, of a great size, remained in that state eighty-two days, and were easily reared. Their cocoon resembles that of the mulberry species. It is composed of a beautiful silk of a silvery whiteness in the interior, and of a more or less bright green on the exterior. The moth is very large and beautiful, of a bright yellow colour, approaching orange.We give a drawing of theAttacus Yama-Maï, taken from the plates which accompany M. Guérin-Méneville's memoir.[65]Fig. 222.—Cocoon of Attacus (Bombyx) Yama-Maï.Fig. 222.—Cocoon of Attacus (Bombyx) Yama-Maï.Fig. 223.—Attacus (Bombyx) Yama-Maï.Fig. 223.—Attacus (Bombyx) Yama-Maï.Fig. 221represents the larva, or caterpillar, two-thirds natural size;Fig. 222, the cocoon, drawn on the same scale; andFig. 223, the moth.In 1866, M. Camille Personnat published a very interesting monograph ofYama-Maï, which may be consulted with profit by both cultivators of silk and naturalists.[66]Attacus pernyiyields a remarkably beautiful silk, fine, strong, and brilliant, which can be spun and dyed with great ease. The tissues obtained from it partake of the qualities of ordinary silk, of wool, and of cotton. This species ofAttacus, which is reared on the oak in Mandchouria, has given rise to great hopes in France. The cocoons and moths of this worm were exhibited for the first time at the Universal Exhibition of 1855. They were reared by M. Jordan, of Lyons, from some cocoons sent over from China by the missionaries. It is much to be desired that this species may be acclimatised in Europe.Fig. 224.—Cocoon of Attacus (Bombyx) pernyi.Fig. 224.—Cocoon of Attacus (Bombyx) pernyi.Figs.224and225represent, after drawings in the Memoir of M. Guérin-Méneville, already referred to, the cocoon and moth of theAttacus pernyi.The silk whichAttacus Mylittaproduces is perhaps superior to that ofPernyi. When the cocoons are properly prepared, the silk can with ease be wound off from one end of them to the other. This worm is found in various parts of Bengal and of Calcutta, and also at Lahore, and its silk is exported in considerable quantities under the name oftusseh. Brownish stuffs are made of it in India offirm and bright texture, which are used for summer clothing, or for covering furniture.Fig. 225.—Attacus (Bombyx) pernyi.Fig. 225.—Attacus (Bombyx) pernyi.Figs.226and227represent the moth and the cocoon ofAttacus Mylittaafter M. Guérin-Méneville.Fig. 226.—Attacus (Bombyx) Mylitta.Fig. 226.—Attacus (Bombyx) Mylitta.In 1855 M. de Chavannes reared this species in the open air, near Lausanne, in Switzerland. This treatment succeeded perfectly,without any degeneration, for many years. It, however, died out at last, from the effects, perhaps, of too great a difference in the climate, or from those accidents, still so little understood, to which even the insects of our own country are subject. This was unfortunate, as this species is one of those whose acclimatisation in Europe is the most to be desired, for it would render great service to the cultivators of silk.It remains for us to speak of two other species, which are very important, inasmuch as their domestication in Europe is now an accomplished fact. We mean theAttacusorBombyxof the Ailanthus, and also that of the Castor-oil plant.Fig. 227.—Cocoon of Attacus (Bombyx) Mylitta.Fig. 227.—Cocoon of Attacus (Bombyx) Mylitta.Every one has heard of the Ailanthus silkworm (Attacus[Bombyx]Cynthia), whose acclimatisation in Europe has been materially assisted by the admirable and persevering efforts of M. Guérin-Méneville.The Ailanthus worm is a native of Japan and of the north of China. It was brought over in 1858 by Annibale Fantoni, and sent to M. Guérin-Méneville by MM. Griseri and Colomba, of Turin. When it is nearly full-grown it is emerald green, with the head, the feet, and the last segment of a beautiful golden yellow, and has black spots on each segment. This worm, in its full-grown state, is represented byFig. 228; in the same figure are also represented the eggs and the cocoon. The moth has the abdomen yellowish underneath, with little white tufts. Its wings are traversed by a white band, which is followed exteriorly by a line of a bright rose; each wing is also marked by a lunula or crescent-shaped spot.In 1858 M. Guérin-Méneville presented to the Académie des Sciences of Paris the first moths and the first eggs laid in France of theAttacus Cynthia. This able entomologist demonstrated very soon afterwards—1st, that the caterpillars of this insect can be reared in the open air, and with scarcely any cost for management; 2ndly, that it produces two crops a year in the climate of Paris and thenorth of France; 3rdly, that the cultivation of the Ailanthus, or the false Japan varnish tree, on which this insect lives, is easy even in the most sterile soil.Fig. 228.—Eggs, larvæ, and cocoons of Attacus (Bombyx) Cynthia.Fig. 228.—Eggs, larvæ, and cocoons of Attacus (Bombyx) Cynthia.M. Guérin-Méneville showed still further thatailantine, the textile matter furnished by the cocoon of the Cynthia, is a sort of floss silk holding a middle place between wool and the silk of the mulberry-tree worm, and which, as it can be produced at scarcely any expense, would be very cheap, and would serve for the fabrication of what are called fancy stuffs, for which ordinary floss silk is now used. In 1862 M. Guérin-Méneville sent in a Report to the Minister ofAgriculture on the progress of the cultivation of the Ailanthus, and of the breeding of the silkworm, which was reared in the open air on this tree. He mentions, in his Report, the rapid development of the cultivation of the tree in France, the great number of eggs of the Ailanthus silkworm sold, the foundation of a model silkworm nursery at Vincennes, and, this one great point gained, that they had found out the way of unwinding the silk from the cocoons of theCynthiain one unbroken and continuous thread.Till then European industry had only succeeded in drawing from the cocoons of the Ailanthus silkworm a floss silk, composed of filaments more or less short, obtained by carding, and unable to produce, when twisted, anything better than floss, that is to say, refuse silk. It is to the Countess de Vernéde de Corneillan, on the one hand, and to Doctor Forgemot on the other, that the merit is due of having obtained an unbroken thread of silk from the cocoon ofAttacus Cynthia.A monograph on the Ailanthus silkworm appeared in 1866 under the title, "L'Ailante et son Bombyx, par Henri Givelet."[67]It is a complete account of all the results obtained up to the time, both as regards the rearing of the silkworm and also as regards the cultivation on a large scale of the Ailanthus, or false Japan varnish tree.[68]The Castor-oil Plant Silkworm (Attacus[Bombyx]ricini) is a species very nearly akin to the Ailanthus worm, perhaps only a variety, and comes from India. The silk which it produces is very similar in every respect to that of theCynthia. The rearing of this worm could never attain to any great importance in France, on account of the necessity there is of renewing the plantations of the castor-oil plant each year. It would, however, afford an additional source of income to the farmers in the south of France, who cultivate the castor-oil plant with a view to selling its seeds, which are much used in pharmacy.Nearly allied to the genusAttacus, which furnishes us with all these precious auxiliaries to the mulberry silkworm, are a great number of other species, both indigenous to Europe and exotic, mostly remarkable for their great size, and a few of which are common in this country.Fig. 229 is the largest European moth, but never found farther north than the latitude of Paris. Its wings are brown, waved, and variegated with grey. Each of them has a large black eye-shaped spot, surrounded by a tawny circle, surmounted by one white semicircle, and by another of a reddish hue, the whole completely enclosed in a black circle. "These moths," says Geoffroy, "are very large; they look as if they were covered with fur, and, when they fly, one is inclined to take them for birds."Fig. 229.—Saturnia pavonia-major.Fig. 229.—Saturnia pavonia-major.Saturnia pavonia-majorcomes from a very large caterpillar, which is of a beautiful green, with tubercles of turquoise blue, each of which is surmounted by seven stiff divergent hairs. This caterpillar lives principally upon the elm, but it feeds also upon the leaves of the pear, plum, and other trees. It spins a brown cocoon, formed of a coarse silk of great strength. It is not until the following spring that it becomes a moth.The Emperor Moth (Saturnia carpini,Fig. 230) much resembles the above, except in size. This species is common in England, and its green larva, covered with black or pink warts, from which spring hairs, as in the last, is by no means rare on heath in the autumn. It also feeds on bramble and other plants.Fig. 230.—Emperor Moth (Saturnia carpini).Among theAttaciforeign to Europe, we must mentionAtlas(Fig. 231), the expanse of whose wings exceeds four and a quarter inches. This magnificent moth, one of the largest known, comes from China.The familyBombycidæcomprises many species which we must not omit to mention.The Lackey (Bombyx neustria) derives its name from the colour of the caterpillar, which has longitudinal lines of various colours, and a blue head. These caterpillars live together on a great number of our forest and garden trees, to which they do much damage. The moth (Fig. 232) has a brownish body, and wings of a more or less tawny yellow colour, with two darker lines on the front wings.The Procession Moth (Bombyx processionea) is a small greyish moth, the caterpillars of which live in numerous troops on oak trees, and devour the leaves at the moment of their development. In theevening these caterpillars come out of their common nest, and form a sort of procession; hence their name Procession Moth. "I kept some for a little time in my house in the country," says Réaumur. "I brought an oak branch which was covered with them into my study,where I could much better follow the order and regularity of their march than I could have done in the woods. I was very much amused and pleased at watching them for many days. I hung the branch on which I had brought them against one of my window shutters. When the leaves were dried up, when they had become too hard for the jaws of the caterpillars, they tried to go and seek better food elsewhere. One set himself in motion, a second followed at his tail, a third followed this one, and so on. They began to defile and march up the shutter, but being so near to each other that the head of the second touched the tail of the first. The single file was throughout continuous; it formed a perfect string of caterpillars of about two feet in length, after which the line was doubled. There two caterpillars marched abreast, but as near the one which preceded them as those who were marching in single file were to each other. After a few rows of our processionists who were two abreast, came the rows of three abreast; after a few of these came those which were four abreast; then there were those of five, others of six, others of seven, others of eight caterpillars. This troop, so well marshalled, was led by the first. Did it halt, all the others halted; did it again begin to march, all the others set themselves in motion, and followed with the greatest precision.... That which went on in my study goes on every day in the woods where these caterpillars live.... When it is near sunset you may see one caterpillar coming out of any of the nests, by the opening which is at the top, which would hardly afford space for two to come out abreast. As soon as it has emerged from the nest, it is followed by many others in single file; when it has got about two feet from the nest, it makes a pause, during which those who are still in the nest continue to come out; they fall into their ranks, the battalion is formed; at last the leader sets off marching again, and all the others follow him. That which goes on in this nest takes place in all the neighbouring nests; all are evacuated at the same time."
Fig. 210.—Silkworm Moth (Bombyx mori), female.
Before laying her eggs, the female looks out for a place suitable for this purpose. When she has found this place, she ejects an egg covered with a viscous liquid, which causes it to adhere to the body upon which it falls. Very soon she lays a second egg by the side of the first, then a third by the side of the second, and so on. She very rarely piles them up on each other. The laying lasts about three days; the number of eggs is from 300 to 700 for each female. These eggs are generally tentacular and flattened towards the centre. At the moment at which they are laid they are of a bright yellow. In a week they become brown. The colour changes then to a reddish grey; lastly it becomes of a slaty grey, remaining this colour during the autumn, winter, and a great part of the spring. Then as the temperature rises, the colour of the eggs passes successively through bluish, violet, ashy, and yellowish shades. And, lastly, they become more and more whitish every day as the hatching time approaches.
If looked at closely, one remarks a black spot and a brownish crescent extending along the circumference. The black spot is the head of the worm, which closely touches the shell; the crescent is the body, which is already covered with little hairs. When it leaves the egg, the silkworm gnaws through the shell on its side, never on its flat surface. When the opening is large enough, it breaks out through it, head foremost, and immediately fixes a thread of silk to any object it can reach, no doubt in order to prevent itself from falling. Sometimes the opening is too small to allow of the head passing out, and the larvais forced to come out backwards, that is to say, tail foremost. At times, not being able to get its head free, the poor animal very soon dies of fatigue and hunger.
VI.—A Silkworm rearing Establishment.VI.—A Silkworm rearing Establishment.
We will now give a summary of the rearing of the silkworm, that is to say, of the attention which must be paid to this insect that it may construct its cocoon advantageously. We will call to our aid in this very rapid summary the works or notices of MM. Robinet, Guérin-Méneville, Eugène Robert, and Louis Leclerc, and we must not forget the excellent and classical Dandolo.[63]
When it is desired to rear silkworms—magnans, as they were called in old French, and as they are still called in the patois of Languedoc—the first thing to do is to obtain good eggs, goodgrain, to use the technical word, and then to choose suitable premises. The essential, the fundamental point, in the rearing, is to possess premises in which the air is easily renewed. The worms should have as much air as possible given to them without ever being allowed to be chilled. There is no better means of attaining this end than by keeping a constant open fire in a room, and by letting air into the room from another chamber which separates it from the open air. One has, in this way, the best workroom for a small rearing.
In the workshop are arranged racks, by the aid of which are placed, at the distance of 50 centimètres from each other, frames made of reeds. These frames, orcanisses, as they are called in the Cévennes, may be from 1 mètre to 1¾ mètres in breadth. They should be placed in such a manner that one can easily pass round them to place and remove the worms, and to distribute their leaves to them uniformly. They should be protected by a small border of a few centimètres in height, to prevent the worms from falling. And lastly, they should be covered at the bottom with large sheets of paper. (Plate VI.) A provident silkworm-rearer has always at his disposal a cellar or cool room, so as to be able to stow away his leaves as soon as they are brought in from the country.
What we have just said applies especially to a small rearing. In large establishments, or even those of second-rate importance, everything is in advance of this, and mathematically regulated: aspect and arrangement of rooms, furniture of these rooms, warming, ventilation,&c. So, for a rearing house for 300 grammes of eggs, the building should be constructed in such a manner that its front and back look east and west, to avoid any inequality in the heat derived from the sun. It ought to consist of a ground-floor, a very lofty first-floor, and of a rather low roof. The ground-floor comprises the chamber of incubation, the store-room for leaves, and the air-chamber with the grate intended for warmth and ventilation. The first-floor constitutes the rearing-room properly so called.
But let us leave these grand industrial establishments, to return to our rearing houses on a small scale, such as are found among the peasants of the Cévennes. They generally receive the silkworms' eggs before the end of the winter. In order to preserve them till the hatching season, they are placed in thin layers, in a piece of folded woollen stuff, which must be hung up in a cool, but not a damp place, exposed to the north. As soon as the buds of the mulberry tree begin to be partially open, they proceed to the incubation of the eggs. They are spread out on sheets of paper, in very thin layers, placed on a table in a room having a southern aspect, and left thus during three or four days, taking care to prevent the rays of the sun from touching them. It is necessary also, from time to time, to open the windows. After three or four days, the fire is lighted, taking care not to have more heat than 13° Centigrade round about the table which supports the eggs, and which should be placed as far as possible from the fire. Each day the room is warmed a little more, in such a way that the temperature is raised 1° to 2° a day, until 25° Centigrade of heat have been attained, at which temperature it is to be maintained when the eggs have reached the last stage, and till the hatching is terminated. On the first day few worms are hatched; but the hatching of the second day is very abundant, as also that of the third. Of these newly-born worms two divisions are made, separated by an interval of twenty-four hours. The worms which are born afterwards are thrown away, unless they are so abundant that they can be made a third batch of, which is to be mixed up with the second at the period of the moult.
In the large rearing houses there is a special chamber for the incubation. Various simple, convenient, cheap apparatuses, whose main object is to create a permanent warm and damp atmosphere, whose degree of heat can be regulated at will, have been proposed. M. Louis Leclerc, in his pamphlet entitled "Petite Magnanerie," has given a description and drawing of a little box which is very useful for facilitating the hatching of eggs. We refer those of our readers who wish for further information on the subject to that work. Assoon as the worms are hatched, the eggs are covered with net, and over this are placed mulberry boughs, covered with tender leaves, on which all the little worms congregate. They are then lifted up with a hook made of thin wire, and the worms are placed on a table covered with paper, leaving a proper space between each. They are given, as their first meal, tender leaves cut into little pieces with a knife. These are the operations gone through for the two raisings of worms on the second and third day of the hatching. During this first age they give them from six to eight meals a day, taking care to distribute their food to them as equally as possible. The first meal is given at five o'clock in the morning; the last at eleven or twelve o'clock at night.
When the moult is approaching, the young ones are made to climb on to boughs having tender leaves, so that they can be moved to litters as thin and clean as possible, and there sleep in a good state of health. When the mass of worms is well awake again, the next thing to do is to take them off the litter on which they moulted, and to give them food. If this problem were proposed to a person strange to the operation which is now occupying our attention—to separate the worms from the faded and withered food upon which they are reposing, without touching them—he would certainly be very much at a loss what to answer. The solution of this problem presented for a long time great difficulties, and occasioned numerous reverses in the rearing. Now-a-days, thanks to the employment of a net, thedélitement, or taking them off their bed, has become an easy operation.
Over the worms, placed on a table, is spread a net, the meshes of which are broad enough to allow them to pass through. On this net are spread the leaves which are to compose a meal. The worms immediately leave the old food, and get on to the new leaves. They then lift the litter with the worms, and throw away the old leaves, now unoccupied, clean the table, and replace the net with the worms. At the nextdélitementthe first net is found under the litter. Figs.211and212represent two forms of these nets made of thread.
Thread nets, which were of great use, have been supplanted lately, with great advantage, by paper ones, which were invented by M. Eugène Robert. These are leaves of paper, of a peculiar manufacture, pierced with holes proportioned to the size of the worms which are to pass through them. The paper net can be used advantageously also for separating the worms that are too near together, or, as they say, for thedédoublement. Formerly, thedélitementand thedédoublementwere done by hand—a tedious work, and one that presented serious disadvantages. Now-a-days, as we have seen, the worms themselves perform these two perilous operations.
At the second age they still cut the leaves for the worms, but into larger pieces, and proportioned to their size. During the day the temperature of the room ought to be kept to 21° Centigrade, but it may be lowered by 1° or 2° during the night. Towards the end of this age they have only four meals. When the worms are on the point of going to sleep, their meals are decreased.
During the third age the number of the meals is kept to four, the first being given towards five o'clock in the morning, and the last between ten and eleven o'clock at night. The leaf is cut into much larger pieces, and distributed as equally as possible. Thedélitementand thedédoublementare proceeded with as in the preceding age. One begins to find pretty often during this period of the life of worms, someluisettes—that is to say, worms which have not strength enough to moult. They are larger than those just woke up, and that have not as yet eaten, and are shiny. They must be carefully removed, for they will not be long before they die, and infect the air of the room.
During the fourth age they no longer cut the leaves, but give them a great deal more at once. The result is that the litters increase in thickness, and that thedélitementmust be performed oftener; for the rest, four meals are always necessary. Manyluisettesmay be seen during the fourth age. The moult which follows the fourth age is the most critical phase in the life of the silkworm. During their sleep they are a prey to acute suffering, and are plunged into a stateof lethargy which resembles death. The dryest and cleanest litters diffuse very soon a sickly smell. This moult lasts from thirty-six to forty-eight hours. During this time the room should be kept to at least 22° Centigrade.
When they awake out of this last sleep the attendant should continually be on his guard, as it is then that diseases break out. The worms suffering from these different diseases have received different names. There are besides theluisettesthearpians—that is to say, worms that have exhausted all their energy in the work of the last moult, and have not even strength to eat—theyellow, orfatworms, which are swollen, of a yellowish colour, and which very easily die; theflatsormous, the soft or indolent ones which, after having eaten a great deal and become very fat, die miserably, and enter into a state of putrefaction. And lastly, it is at this age that themuscardine, which hardly shows itself at any other age of the insect, appears with great intensity.
Themuscardineis a terrible scourge to the rearers of silkworms. The losses which result from this disease in France are estimated at at least one-sixth of the profits. No particular symptom allows of our recognising the existence of this disease in worms which, however, contain its germ; only, the worm, which has eaten up to that time as usual, appears almost in a moment to change to a duller white; its movements become slower, it becomes soft, and is not long before it dies. Seven or eight days after its death it becomes reddish and completely rigid. Twenty four hours afterwards a white efflorescence shows itself round the head and rings, and soon after the whole body becomes floury. This flour is a fungus calledBotrytis bassiana, of which themyceliumdevelops itself in the fatty tissue of the caterpillar, attacks the intestines, and fructifies on the exterior. This fungus has been considered as the immediate cause of themuscardine, and has been also regarded as the last symptom or end of the disease. The communication of the disease by contagion has alternately been admitted and denied. As its true cause, and any efficacious means of opposing it, are still unknown, the breeders of silkworms must be content to apply—so as to prevent or struggle against this dreadful scourge—the precepts of hygiene: good ventilation, excessive cleanliness, frequentdélitements, and good food properly prepared.
After themuscardine, we must mention another epidemic disease still more terrible, thegattine. This disease shows itself from the very beginning of the rearing, and increases in intensity at each age, so that the number of worms able to enter regularly into the moultbecomes smaller and smaller. We are still in a state of utter ignorance as to the cause of this last affection, which has occasioned, for the last ten years, incalculable losses in the rearing houses, which threatens the silkworm with complete destruction, and which in the meanwhile has ruined the unfortunate countries of the Cévennes, the principal seat of sericulture in France.
During the fifth age, the worms become large so quickly that on the fifth or sixth day they are obliged to be moved away from each other on the litter. Thedélitementmust be made every two days, or indeed, every day now, on account of the enormous amount of the excrement; and, at the same time, a good ventilation must be constantly maintained. The temperature of the room should now be kept to 24°, without ever exceeding this degree of heat. When it is perceived that the worms wish to ascend, ormount, there are placed on the tables, at certain distances from each other, little sprigs of heather or very dry branches of light wood.
Fig. 213.—Sprigs of heather arranged so that Silkworms may mount into them.
When the worms begin to mount into the heather, one mustencabaner—that is to say, form with these branches little hedges, curved back like a hut or cradle, the openings of which are, on an average, seventeen inches or so (Fig. 213). At the expiration of twenty-four hours all the good worms have mounted. The laggards who remain under thecabanesare taken off by hand, and placed on a table, which is immediatelyencabanea.
The cocoons spun on these branches of heather ought to be large, heavy, and well-shaped. The good cocoons are regular; their ends are rounded and not pierced; and they are hard, especially at their extremities, and have a fine grain. They are cylindrical. The best are drawn in towards the middle, or have a concavity on either side of it (Fig. 215). Every one knows that there are white and yellow cocoons. They are the produce of different races of worms.
Commerce recognises two kinds of white silk: thefirst whiteand thesecond white. The silk of thefirst whiteis produced by the raceSina, the cocoons of which are of a perfect and azured white. They produce the most beautiful and most precious silk, and serve for the fabrication of light and delicate coloured tissues. The silk of thesecond whiteis furnished by two races: theEspagnoletand theRoquemaure.
The races that produce yellow cocoons are more numerous than the white ones. The yellow races are divided into three groups: those that have small, middle-sized, or large cocoons. The first and second are stronger, and more esteemed than the last.
The greater number of the races of silkworms have, let us here mention, white and yellow cocoons; there are some, however, whose cocoons are of a greenish white, or even quite green, or of a reddish green. One race, raised in Tuscany, near Pistoia, has cocoons of a pale rose colour; and, lastly, mention has been made of cocoons of a purple colour.
Fig. 216.—Larva, pupa, cocoon, and moth of Bombyx mori.Fig. 216.—Larva, pupa, cocoon, and moth of Bombyx mori.
When the cocoons are completed, the people in charge of the rearing establishments separate them from the heather and sell them to the silk-spinners. But they must manage to get these cocoons into a state in which they will remain entire during a long time. They must, in other words, kill the chrysalis, to prevent the cocoons being pierced by the moth. To kill the chrysalis so as to prevent thedevelopment of the imago is an operation which is called theétouffage, or stifling.
Fig. 217.—Apparatus for stifling the chrysalides in the cocoons.
To effect this stifling, the cocoons are exposed to a high temperature. Formerly, in the Cévennes, the cocoons were placed in abaker's oven, heated for baking bread. But they ran the risk thus of being burnt, or of a certain number of chrysalides remaining alive. Now, to kill the chrysalides, they make use of steam at 100°, produced by water boiling in a vessel, and which passes through wicker baskets filled with cocoons.
The rearer must also take care at the time he gathers them, to separate the cocoons which are to provide eggs for the next year. As the female cocoons are heavier than the male cocoons, they are easily separated by weighing them in a pair of scales.
To obtain the eggs, or grain, the cocoons are fixed on sheets of brown paper, covered with a slight coating of paste made of flour. They are arranged in such a manner that the moths shall find no obstacle when they come out of them, head foremost; and, moreover, so that they may be able to reach with their legs the cocoon which is opposite them, so as to hang on to it, and to facilitate their exit from their own cocoon (Fig. 218). The male and female cocoons are pasted on separate sheets.
Fig. 218.—Sheet of paper with rows of cocoons prepared for the exit of the moths destined for laying eggs.Fig. 218.—Sheet of paper with rows of cocoons prepared for the exit of the moths destined for laying eggs.
Fig. 219.—Sheets of paper stuck into screens, and inclined for the reception of moths.Fig. 219.—Sheets of paper stuck into screens, and inclined for the reception of moths.
It is from fifteen to twenty days after themontée, ormounting, and when the temperature of the rooms has been kept between 20° and 25°, that the moths begin to be hatched. As they appear, they are seized by the wings and placed on cloths stretched out for the purpose, where they are left for about an hour, till their wings have fallen flat on their bodies. As soon as they have evacuated a red liquor, the males and females, which up to that time have been apart, are put together.
They then stick sheets of paper on to screens, putting from twenty-five to thirty females on each sheet (Fig. 219). It is here the moths lay their eggs. The sheets of paper, covered with eggs, are then hung on wires, at a small distance from the ceiling of a roomhaving a northern aspect, which is never warmed. They remain thus, exposed to all variations of temperature, till the return of the warm weather. We will say a few words, to bring this subject to an end, on the winding of cocoons and the spinning of silk.
The winding of cocoons is an operation which at first sight appears very simple, but which is in reality a difficult and delicate process. It requires unremitting attention, great experience, and a delicacy of touch which can only be found in the fingers of woman, or rather, in the fingers of certain women.
The woman who is spinning, stands before a sort of loom which is calledtour(Fig. 220). Under her hand is a copper containing water, which she heats to the required degree by opening the tap of a tube, which brings a current of steam. She plunges the cocoons into the hot water, and moves them about in it, to soften the gummy substance which sticks the silken threads of the cocoon together. Then she beats them, with a light hand, with a small birch-broom. The threads of the cocoons get caught in the extremities of the twigs of which the little broom is made, and the workwoman seizes with her fingers the bundle of threads, and shakes them about till she perceives that they are all single, and in a fit state to be joined together.
Fig. 220.—Silk-winding Establishment.Fig. 220.—Silk-winding Establishment.
Let us suppose that it is wished now to make up abrin, or staple, by uniting together the ends of five cocoons. She chooses five ends in the mass, makes of these a bundle, and introduces it into the hole of afilière. She makes two staples (brins) at once, one on her right, the other on her left hand. She then brings them together, she crosses them, rolls them, and twists them, the one on the other, several times; after which, she separates them from above and keeps them well apart, making each of them pass into a hook at a distance, from which they are going to twist round into a hank, separately, on a wheel. The two threads thus twisted are drawn close together, compressed, and become one, getting round by rolling on each other, and being kept in continual motion, drawn out as they are by the rapid motion of the wheel.
The difficulty which the emptying the cocoon of its silk thread presents, makes us understand what difficulties those manufacturers must have met with who have lately attempted to extract from the stalks of mulberry leaves a sort of silk. We will enter into no details of the attempts which have been made to accomplish this object in our time, attempts which have, however, been crowned with no success whatever. We will confine ourselves to reminding the reader that these attempts are far from being of recent origination, since they date back to as far as Olivier de Serres, the father of French sericulture.
In a little work published by Olivier de Serres, in 1603, under the title ofCueillette de la Soie, "The Gathering of Silk," we find a memoir entitled:La second richesse du mûrier, qui se trouve en son escorce, pour en faire des toiles de toute sorte, non moins utile que la soie provenant d'icelui, "The second wealth of the mulberry tree which is found in its bark, how to make of it cloth of all sorts, not less useful than the silk derived from this tree." Olivier de Serres proves in this memoir that the second bark, orliber, of the mulberry tree contains a fibre capable of replacing hemp or flax, and he describes the processes by which this may be obtained. The processes which had been proposed by Olivier de Serres in 1603, were resumed in the Cévennes a dozen years ago by M. Duponchel on the one hand, and on the other by M. Cabanis,[64]who operated on the bark instead of taking the whole of the wood of the mulberry tree. But none of these attempts have given any good results up to the present moment.
The various diseases which for the last fifteen years have been so fatal to the mulberry silkworm, have suggested the idea of acclimatising in Europe other silk-producing Bombyces, if not with the view of superseding, at least as auxiliaries to the mulberry species. The genusAttacushas furnished these auxiliaries. Among the species which have, in this respect, the greatest claims to our attention, we must place in the first rank those which feed upon the leaves of the oak tree. Indeed, the trees which can be made use of for their cultivation are very numerous in Europe, and, moreover, the silk produced by these worms appears to possess superior qualities.
There are three oak-feeding species of the genusAttacus. They areYama-Maï,Pernyi, andMylitta.
Fig. 221.—Larva of Attacus (Bombyx) Yama-Maï.Fig. 221.—Larva of Attacus (Bombyx) Yama-Maï.
The silk ofYama-Maïis as bright as that of the mulberry silkworm, but a little less fine and strong, and occupies the first rank after it. If we could succeed in acclimatising this species it would supply any deficiency there might be in our crops of ordinary silk.
The eggs of theAttacus Yama-Maïwere brought from Japan—where this worm is reared—conjointly with the mulberry silkworm, in 1862. The larvæ hatched at Paris, in 1863, were green, of a great size, remained in that state eighty-two days, and were easily reared. Their cocoon resembles that of the mulberry species. It is composed of a beautiful silk of a silvery whiteness in the interior, and of a more or less bright green on the exterior. The moth is very large and beautiful, of a bright yellow colour, approaching orange.
We give a drawing of theAttacus Yama-Maï, taken from the plates which accompany M. Guérin-Méneville's memoir.[65]
Fig. 222.—Cocoon of Attacus (Bombyx) Yama-Maï.Fig. 222.—Cocoon of Attacus (Bombyx) Yama-Maï.
Fig. 223.—Attacus (Bombyx) Yama-Maï.Fig. 223.—Attacus (Bombyx) Yama-Maï.
Fig. 221represents the larva, or caterpillar, two-thirds natural size;Fig. 222, the cocoon, drawn on the same scale; andFig. 223, the moth.
In 1866, M. Camille Personnat published a very interesting monograph ofYama-Maï, which may be consulted with profit by both cultivators of silk and naturalists.[66]
Attacus pernyiyields a remarkably beautiful silk, fine, strong, and brilliant, which can be spun and dyed with great ease. The tissues obtained from it partake of the qualities of ordinary silk, of wool, and of cotton. This species ofAttacus, which is reared on the oak in Mandchouria, has given rise to great hopes in France. The cocoons and moths of this worm were exhibited for the first time at the Universal Exhibition of 1855. They were reared by M. Jordan, of Lyons, from some cocoons sent over from China by the missionaries. It is much to be desired that this species may be acclimatised in Europe.
Fig. 224.—Cocoon of Attacus (Bombyx) pernyi.Fig. 224.—Cocoon of Attacus (Bombyx) pernyi.
Figs.224and225represent, after drawings in the Memoir of M. Guérin-Méneville, already referred to, the cocoon and moth of theAttacus pernyi.
The silk whichAttacus Mylittaproduces is perhaps superior to that ofPernyi. When the cocoons are properly prepared, the silk can with ease be wound off from one end of them to the other. This worm is found in various parts of Bengal and of Calcutta, and also at Lahore, and its silk is exported in considerable quantities under the name oftusseh. Brownish stuffs are made of it in India offirm and bright texture, which are used for summer clothing, or for covering furniture.
Fig. 225.—Attacus (Bombyx) pernyi.Fig. 225.—Attacus (Bombyx) pernyi.
Figs.226and227represent the moth and the cocoon ofAttacus Mylittaafter M. Guérin-Méneville.
Fig. 226.—Attacus (Bombyx) Mylitta.Fig. 226.—Attacus (Bombyx) Mylitta.
In 1855 M. de Chavannes reared this species in the open air, near Lausanne, in Switzerland. This treatment succeeded perfectly,without any degeneration, for many years. It, however, died out at last, from the effects, perhaps, of too great a difference in the climate, or from those accidents, still so little understood, to which even the insects of our own country are subject. This was unfortunate, as this species is one of those whose acclimatisation in Europe is the most to be desired, for it would render great service to the cultivators of silk.
It remains for us to speak of two other species, which are very important, inasmuch as their domestication in Europe is now an accomplished fact. We mean theAttacusorBombyxof the Ailanthus, and also that of the Castor-oil plant.
Fig. 227.—Cocoon of Attacus (Bombyx) Mylitta.Fig. 227.—Cocoon of Attacus (Bombyx) Mylitta.
Every one has heard of the Ailanthus silkworm (Attacus[Bombyx]Cynthia), whose acclimatisation in Europe has been materially assisted by the admirable and persevering efforts of M. Guérin-Méneville.
The Ailanthus worm is a native of Japan and of the north of China. It was brought over in 1858 by Annibale Fantoni, and sent to M. Guérin-Méneville by MM. Griseri and Colomba, of Turin. When it is nearly full-grown it is emerald green, with the head, the feet, and the last segment of a beautiful golden yellow, and has black spots on each segment. This worm, in its full-grown state, is represented byFig. 228; in the same figure are also represented the eggs and the cocoon. The moth has the abdomen yellowish underneath, with little white tufts. Its wings are traversed by a white band, which is followed exteriorly by a line of a bright rose; each wing is also marked by a lunula or crescent-shaped spot.
In 1858 M. Guérin-Méneville presented to the Académie des Sciences of Paris the first moths and the first eggs laid in France of theAttacus Cynthia. This able entomologist demonstrated very soon afterwards—1st, that the caterpillars of this insect can be reared in the open air, and with scarcely any cost for management; 2ndly, that it produces two crops a year in the climate of Paris and thenorth of France; 3rdly, that the cultivation of the Ailanthus, or the false Japan varnish tree, on which this insect lives, is easy even in the most sterile soil.
Fig. 228.—Eggs, larvæ, and cocoons of Attacus (Bombyx) Cynthia.Fig. 228.—Eggs, larvæ, and cocoons of Attacus (Bombyx) Cynthia.
M. Guérin-Méneville showed still further thatailantine, the textile matter furnished by the cocoon of the Cynthia, is a sort of floss silk holding a middle place between wool and the silk of the mulberry-tree worm, and which, as it can be produced at scarcely any expense, would be very cheap, and would serve for the fabrication of what are called fancy stuffs, for which ordinary floss silk is now used. In 1862 M. Guérin-Méneville sent in a Report to the Minister ofAgriculture on the progress of the cultivation of the Ailanthus, and of the breeding of the silkworm, which was reared in the open air on this tree. He mentions, in his Report, the rapid development of the cultivation of the tree in France, the great number of eggs of the Ailanthus silkworm sold, the foundation of a model silkworm nursery at Vincennes, and, this one great point gained, that they had found out the way of unwinding the silk from the cocoons of theCynthiain one unbroken and continuous thread.
Till then European industry had only succeeded in drawing from the cocoons of the Ailanthus silkworm a floss silk, composed of filaments more or less short, obtained by carding, and unable to produce, when twisted, anything better than floss, that is to say, refuse silk. It is to the Countess de Vernéde de Corneillan, on the one hand, and to Doctor Forgemot on the other, that the merit is due of having obtained an unbroken thread of silk from the cocoon ofAttacus Cynthia.
A monograph on the Ailanthus silkworm appeared in 1866 under the title, "L'Ailante et son Bombyx, par Henri Givelet."[67]It is a complete account of all the results obtained up to the time, both as regards the rearing of the silkworm and also as regards the cultivation on a large scale of the Ailanthus, or false Japan varnish tree.[68]
The Castor-oil Plant Silkworm (Attacus[Bombyx]ricini) is a species very nearly akin to the Ailanthus worm, perhaps only a variety, and comes from India. The silk which it produces is very similar in every respect to that of theCynthia. The rearing of this worm could never attain to any great importance in France, on account of the necessity there is of renewing the plantations of the castor-oil plant each year. It would, however, afford an additional source of income to the farmers in the south of France, who cultivate the castor-oil plant with a view to selling its seeds, which are much used in pharmacy.
Nearly allied to the genusAttacus, which furnishes us with all these precious auxiliaries to the mulberry silkworm, are a great number of other species, both indigenous to Europe and exotic, mostly remarkable for their great size, and a few of which are common in this country.
Fig. 229 is the largest European moth, but never found farther north than the latitude of Paris. Its wings are brown, waved, and variegated with grey. Each of them has a large black eye-shaped spot, surrounded by a tawny circle, surmounted by one white semicircle, and by another of a reddish hue, the whole completely enclosed in a black circle. "These moths," says Geoffroy, "are very large; they look as if they were covered with fur, and, when they fly, one is inclined to take them for birds."
Fig. 229.—Saturnia pavonia-major.Fig. 229.—Saturnia pavonia-major.
Saturnia pavonia-majorcomes from a very large caterpillar, which is of a beautiful green, with tubercles of turquoise blue, each of which is surmounted by seven stiff divergent hairs. This caterpillar lives principally upon the elm, but it feeds also upon the leaves of the pear, plum, and other trees. It spins a brown cocoon, formed of a coarse silk of great strength. It is not until the following spring that it becomes a moth.
The Emperor Moth (Saturnia carpini,Fig. 230) much resembles the above, except in size. This species is common in England, and its green larva, covered with black or pink warts, from which spring hairs, as in the last, is by no means rare on heath in the autumn. It also feeds on bramble and other plants.
Fig. 230.—Emperor Moth (Saturnia carpini).
Among theAttaciforeign to Europe, we must mentionAtlas(Fig. 231), the expanse of whose wings exceeds four and a quarter inches. This magnificent moth, one of the largest known, comes from China.
The familyBombycidæcomprises many species which we must not omit to mention.
The Lackey (Bombyx neustria) derives its name from the colour of the caterpillar, which has longitudinal lines of various colours, and a blue head. These caterpillars live together on a great number of our forest and garden trees, to which they do much damage. The moth (Fig. 232) has a brownish body, and wings of a more or less tawny yellow colour, with two darker lines on the front wings.
The Procession Moth (Bombyx processionea) is a small greyish moth, the caterpillars of which live in numerous troops on oak trees, and devour the leaves at the moment of their development. In theevening these caterpillars come out of their common nest, and form a sort of procession; hence their name Procession Moth. "I kept some for a little time in my house in the country," says Réaumur. "I brought an oak branch which was covered with them into my study,where I could much better follow the order and regularity of their march than I could have done in the woods. I was very much amused and pleased at watching them for many days. I hung the branch on which I had brought them against one of my window shutters. When the leaves were dried up, when they had become too hard for the jaws of the caterpillars, they tried to go and seek better food elsewhere. One set himself in motion, a second followed at his tail, a third followed this one, and so on. They began to defile and march up the shutter, but being so near to each other that the head of the second touched the tail of the first. The single file was throughout continuous; it formed a perfect string of caterpillars of about two feet in length, after which the line was doubled. There two caterpillars marched abreast, but as near the one which preceded them as those who were marching in single file were to each other. After a few rows of our processionists who were two abreast, came the rows of three abreast; after a few of these came those which were four abreast; then there were those of five, others of six, others of seven, others of eight caterpillars. This troop, so well marshalled, was led by the first. Did it halt, all the others halted; did it again begin to march, all the others set themselves in motion, and followed with the greatest precision.... That which went on in my study goes on every day in the woods where these caterpillars live.... When it is near sunset you may see one caterpillar coming out of any of the nests, by the opening which is at the top, which would hardly afford space for two to come out abreast. As soon as it has emerged from the nest, it is followed by many others in single file; when it has got about two feet from the nest, it makes a pause, during which those who are still in the nest continue to come out; they fall into their ranks, the battalion is formed; at last the leader sets off marching again, and all the others follow him. That which goes on in this nest takes place in all the neighbouring nests; all are evacuated at the same time."