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,

Gue'rin-Meneville, Eugene Robert, and Louis Leclerc, and we must not forget the excellent and classical Dandolo.*

When it is desired to rear silkworms — uiagnans^ as they were called in old French, and as they are still called in the patois of Languedoc — the hrst thing to do is to obtain good eggs, good gi-ain^ 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 centimetres from each other, frames made oi reeds. These frames, or canisses, as they are called in the Cevennes, may be from i metre to i J metre 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 centimetres 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 isin advance of this, and mathematically regulated: aspect and arrangement of rooms, furniture of these rooms, warming, ventilation,

**L'Art d'elever des Vers a Sole, par le Comte de Dandolo, trnduit par Philibert Fontaneilles." In 8vo. Lyons, 1825. Robinet, *' Manuel de I'Education des Vers a Soie." In 8vo. I'aris. Guerin-Meneville et Eugene Robert, *♦ Manuel de I'Education des Vers a Soie." In i8nio. Paris. Louis Leclerc, ." Petite Magnanerie." In iSmo. Paris.

&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 Cevennes. 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 lime 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 oi 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 farther information on the subject to that work. As

soon 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 long time great difficulties, and occasioned numerous reverses in the rearing. Now-a-days, thanks to the employment of a net, the delitemeftt, 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 at once leave the old food, and get on to the new leaves. Attendants 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 next delitement the first net is found under the litter. Figs. 211 and 212 show two forms of these nets made of thread.

Thread nets, which were of great use, have been supplanted with great advantage by paper ones, which were invented by M. Eugene 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 the dedoublement. Formerly, the delitement and the dedoublement were 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 i^ or 2° during the night. Towards the

Lozenge-shaped net. Fig. 212 — Square net.

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. The delitcnicnt and the dedoublaticut are proceeded with as in the preceding age. One begins to find pretty often during this period of the life of worms, some luisettes — 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 the rearers no longer cut the leaves, but give them a great deal more at once. The result is the litters increase in thickness, and the delitement must be performed oftener; for the rest, four meals are always necessary. Many luisettes may 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 stat

LEPIDOPTERA. 233I

of lethargy which resembles death. The dryest and cleanest litters diffuse very soon a sickly smell. This moult lasts irom 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 the hUsettes the arpians — 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 — the yelloiv^ or fat worms, which are swollen, of a yellowish colour, and which very easily die; the flats or mous^ 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 the mtiscardine, which hardly shows itself at any other age of the insect, appears with great intensity. The muscardhie is a terrible scourge to the rearers of silkworms. The losses which result from this disease in France are estimated at ac 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 grows 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 called Botrytis bassiajia, of which the mycelium develops 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 the mus-car dine, 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 efiicacious 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, frequent delitements^ and good food properly prepared.

Page 39 of 88