"I have seen them," says a minute observer, "stop when descending, and remain with the head downwards, the wish to eat having ceased before they reached the bottom." In such a case, they should be turned with their heads upwards, as the contrary position is injurious to them. If, at this time, many appear weak and inert, remaining motionless on the leaves, neither eating nor giving any sign of rising to spin, some means must be taken to stimulate them to the exertion. It was the ancient practice and found to be efficacious for this purpose, to convey some pungent article, such as fried onions, into the apartment, the effluvia from which revived the worms, inciting some to take their last meal, and inducing others, whose desire for food had ceased, to climb the twigs and begin their labors. The same end is now generally and unfailingly attained, by removing the sluggish worms into another apartment, the temperature of which is higher.

All these minute directions may perhaps appear frivolous; but it is only by an unceasing attention to these and the like minutiæ, that any tolerable success can be secured. When all the previous cares and labors of an establishment have been satisfactorily accomplished, if the hedges be not well formed, are irregular, or too thick in any parts, so as either to impede the circulation of air, or too far to limit the space in proportion to the number of worms, ill success will be sure to follow. Instead of the proper number of fine single cocoons, many will be double, others imperfect or soiled, and even some of the silkworms will be suffocated before the completion of their labors.

It is essential, in every age of the worms, to attend to the regulation of temperature in their apartments; and at no time is this more necessary than while they are forming their cocoons. If, at this time, they are exposed to much cold, they desist from their labors. Should the balls be suf ficiently thin, the insects may be discerned, either quite inactive, or moving very slowly. On the temperature being raised, they will immediately resume their work with renewed activity, and will once more desist, if the cold be again allowed to exert its influence. After they have remained inactive from this cause for a short time, they put off their caterpillar form, and assume that of the chrysalis, without having sufficient energy to complete their silken covering.

The fifth volume of the transactions of the Society for the Encouragement of Arts, &c. contains a letter upon this subL

ject from a gentleman, who relates, that in the summer of 1786 he had successfully reared to their full growth more than thirty thousand silkworms, when at the beginning of July, and just as they appeared about to spin, a chilling northeast wind set in, and many of the worms became chrysalides, without attempting to spin. On the examination of these, it appeared that the glutinous matter in their silk reservoirs had become so congealed by the cold, as to resemble strong tendons, both in appearance and tenacity; which sufficiently accounted for the inability of the insects to draw forth the silk in filaments. Thousands of the worms changed in this profitless manner daily, until at length, the survivors being removed into an apartment artificially warmed, they imme diately applied themselves to the performance of their usual functions. It is desirable that while silkworms are in the act of spinning, the temperature of their apartment should be maintained as high as 70 degrees, and it is at the same time equally important that free ventilation should be secured.

The opinion has been very generally entertained that violent noise disturbs, and injuriously affects the worms, and that any sudden report, as of fire-arms or thunder, will cause them to fall from their arbors. The peasants in Italy who attend on silkworms are so strongly of this opinion, that if the caterpillars omit to rise and spin after thunder has been heard, they consider its noise as the sole reason of the failure: they are always desirous of removing every cause for noise from about the establishment. This opinion appears, however, to be badly founded, and has been satisfactorily refuted by persons who have made experiments to ascertain the fact. Silkworms have been reared in all the bustle of a town, exposed to the barking of dogs, and to concerts of music, without in any way exhibiting signs of being affected by the noise. The following statement is conclusive. It is taken from the "Cours d'Agriculture," written by Monsieur Rozier, and recounts an experiment performed in the establishment of Monsieur Thomé, a considerable silk cultivator, and one of the earliest writers on the subject. These gentlemen, Messrs. Rozier and Thomé, in the presence of many witnesses, fired several pistol-shots in the apartment where silkworms were either spinning, or rising preparatory to their labor; and the only worm that dropped was evidently a sickly insect, that could not have formed its cocoon under any circumstances.

It is seldom that any opinion upon a point of practice is entertained, without some ground for its existence. The

Italian peasants, although certainly wrong in attributing any evil effects to the agency of noise, might have been correct had they ascribed the evil to that great accumulation of electricity in the atmosphere which attends the discharge of the fluid, from one cloud which is overcharged upon another which is deficient; or which accompanies the fluid in its passage between the clouds and the earth, until an equilibrium establishes itself in the mass. "Before this equilibrium is gained, however," says Monsieur Rozier, "we know that many persons exhibit symptoms of strong excitement, falling into convulsions, or even being affected by fever. Is it, then, surprising, that insects charged with a matter so highly electric as silk should become oppressed or overpowered by the superaddition of that which they receive from the atmosphere?" The peasants in the silk provinces of France have long been accustomed to place pieces of iron in the neighborhood of the insects. If asked to assign their motive for this, their reply is, that their fathers and grandfathers did so before them, and that therefore the practice must be desirable. May we not imagine that this custom had its rise from the remarks of some philosophic observer of the laws of nature, and who, under other and more favorable circumstances, might have been led, by generalizing, to anticipate the discoveries of Franklin?

Monsieur Rozier, in the work already quoted, recommended the use of metallic conductors; and himself proved their efficacy. In connexion with some shelves containing silkworms, he placed thin iron wires, and carried them through the wall into a cistern of water. The remaining shelves were, in every other respect, similarly circumstanced to these; but he uniformly found that, when thus protected, the worms were decidedly more healthy and active than those unprovided with conductors,

CHAP. V.

GATHERING AND SORTING COCOONS.

Method of Gathering. Sorting. Selecting for Seed-Proportion set apart for Breeding.-Methods of destroying Vitality of Chrysalides.-By the Solar Rays.-In Ovens-By Steam Heat.-Preservation of Cocoons.Separation of Damaged.-Good Cocoons.-Pointed Cocoons.-Cocalons. -Dupions.-Soufflons.-Perforated Cocoons.-Choquettes.-Calcined Cocoons. Their Relative Value.-Proportion of Pure Silk in Cocoons.— Proportional Weight of Eggs, and Cocoons; and of Mulberry Leaves.Quantity of Reeled Silk from each Cocoon.-Weight and Size.-Labor required.-Deductions.

In either three or four days from the commencement of its labors the silkworm completes its cocoon, and in seven or eight days thereafter the balls are gathered. Some persons do not wait longer than three or four days ere they reap their silken harvest.

It is usual to begin by gathering from the lower tier of arbors. In this proceeding no violence should be used to disengage the twigs, which must be gently handled, and consigned to those whose employment it is to separate the cocoons. These persons, as they pick off the balls, sort them; selecting those which are to be preserved for continuing the breed, and putting into distinct baskets all fine cocoons, those which are double, soiled, or anywise imperfect. The fine and well-formed balls are again subdivided into white and yellow, the latter color embracing every shade from the deepest yellow to those which are merely tinged. A very few will sometimes be found having a pale-green hue. The cocoons of a bright yellow yield a greater weight of reeled silk than the others, but as their deeper color results from the greater proportion of gum wherein the coloring matter principally resides, any advantage from this source accrues only to the grower, the gummy substance being all boiled out previous to the weaving of the silk.

Raw silk which is of pale color is found to take certain dyes better, and is on that account very generally preferred. The selection of chrysalides for breeding is made from such cocoons as are perfectly sound, and whose threads appear to be fine; having their ends round and compact; and being a little depressed in the middle, as if tightened by a ring or ligature. The reason given for attention to these particulars, is the belief that worms producing such balls are of the strongest constitutions. Count Dandolo was of opin

ion that too much stress is laid upon this point, and that all cocoons which are perfectly formed are alike desirable for breeding. For this purpose an equal number of males and females must be preserved. The former are distinguishable by being sharper at the ends, and this, although not an unerring guide, proves sufficiently correct for all practical purposes. These cocoons are sometimes spread in thin layers on tables: but it seems a better practice, and one more generally adopted, to string them together on a thread, care being taken not to pass the needle too deep into the silk. These strings, three or four feet in length, are then hung in festoons out of the reach of vermin. The floss is, in this case, usually removed, as it is found to oppose additional difficulty to the moth in its extrication.

In making the selection of cocoons for breeding, so as to insure the object of maintaining the numbers of his silkworms, the cultivator considers it necessary to set apart one sixtieth of his whole produce. This shows how considerable must be the loss sustained in this branch of the pursuit. If all the eggs produced by this proportion were found productive, the brood would by their means be trebled in the following season.

The next proceeding is that of destroying the vitality of the chrysalides in those cocoons which are to be reeled. Various methods are employed for this purpose, according to the nature of the climate; the solar rays being in some instances found sufficient, no artificial means need be then resorted to. In this case, a calm and cloudless day is chosen, and the cocoons are left exposed to the scorching beams of the sun, during four or five hours in the middle of the day. They are next closely enwrapt in coarse cloths which have been exposed to the same heat, black cloths being chosen preferably on account of their absorbing a greater quantum of heat. These processes being repeated during several days, the destruction of the insect is usually attained. It is not safe, however, without examination, to confide in its efficacy; for this trial a few chrysalides must be stripped and pricked with a needle. If upon this they give no sign of animation, it may be safely concluded that their suffocation has been perfected.

In more temperate regions artificial means must necessarily be employed, and recourse is therefore had to the heat of steam, or of an oven; and most frequently the latter method is adopted, although there is no reason to doubt that the other, provided it could be efficaciously applied by means of convenient apparatus, would be more quick and certain