diately and with avidity began to feed, preferring it to every substitute which was offered, and thriving upon it satisfactorily. While the hope still remained of naturalizing the silkworm in England, the means of procuring a sufficient supply of appropriate food was considered as one of the greatest obstacles to its success; and the attention of such persons as interested themselves in the pursuit was consequently engaged, in ascertaining by experiment whether other leaves than those furnished by the mulberry tree might not be favorably substituted. Among others, the Rev. Mr. Swayne exhibited much anxiety for the success of this object, with the praiseworthy desire of providing profitable employment for such of the poorer classes as might be too feeble for manual labor, most of the duties required in attendance upon the silkworm being such as can easily be fulfilled by women, children, and aged persons. This gentleman made various trials as to the relative merits of different kinds of nourishmeut. For this purpose he placed equal numbers of newly-hatched worms in three different boxes, which he numbered 1, 2, and 3. The contents of number 1. he fed entirely with leaves of the white mulberry; the insects in number 2. were nourished with those of the black mulberry; and the worms in number 3. were furnished with lettuce leaves until their first age was passed, and thereafter with the black mulberry leaf. These last worms were of a paler color, and grew more rapidly than the others. The result, however, seems to prove that, although lettuce leaves may yield bodily nourishment to the insect, they contribute little towards the secretion of that peculiar matter which constitutes its value. When the spinning had been completed, twelve of the finest cocoons were chosen from each of the three divisions, and were found to be of the following weights: Cocoons of No. 1. weighed 7 dwts. 2 grains. Ditto No. 2. Neither of these results was very encouraging to the cultivator, but the experiment clearly evinced the superiority of the white mulberry over the other kinds of nourishment. Many communications upon this subject are to be found in the volumes recording the Transactions of the Society for the Encouragement of Arts, &c. A letter from Miss Rhodes relates, that in the summer of 1785, she subsisted several thousand worms entirely on lettuce leaves during three weeks, and that for the remaining short term of their lives she afforded them their natural food. At the end of a month from their first hatching they began to spin, and eleven ounces of silk were procured from four thousand cocoons. After repeated trials, this lady had become convinced that silkworms could not safely be fed on lettuce leaves for a longer period than three weeks; as on persisting further in their use, the greater part of the worms died without forming their cocoons. Some, indeed, possessed sufficient vigor to spin and to produce perfect and well-formed balls, even when lettuce leaves had constituted their only food. Reasoning from this fact, Miss Rhodes was brought to suspect that the premature mortality of her brood was not altogether occasioned by the unwholesome nature of the aliment on which they had fed, but might be owing to some extraneous circumstance; and further observation led her to the conclusion that it was the coldness of the lettuce leaves rather than any inherent property which made them detrimental. This lady having thence suggested that if the worms were kept in a higher temperature, they might be successfully supported through their lives on lettuce leaves, general Mordaunt caused a considerable number to be hatched and reared in his hot-house. These were fed entirely on lettuce leaves; they throve and went through all their mutations as satisfactorily as if fed with their natural nourishment; scarcely any among them died, and the number and quality of the cocoons that were gathered proved the entire success of the experiment. If a solitary trial be sufficient to establish a fact, this must certainly be satisfactory to those who consider it desirable to naturalize silkworms in this country, where, owing to the inequality of seasons, the appearance of mulberry leaves must always be uncertain in regard to time. Lettuce leaves have an advantage over other vegetables which have been offered as substitutes for the mulberry, that they may be gathered in wet weather without themselves being wetted, as a lettuce, once cabbaged, resists the entrance of all moisture within; and the heart being always perfectly dry, insures nourishment to the worm, free from that moisture which is always found to affect it injuriously. Mrs. Williams, an earlier correspondent of the society whose "Transactions" have been quoted, gives a very minute and copious account of the various trials which she made of vegetable substances as substitutes for mulberry leaves. Having hatched her brood in severely cold weather, when even lettuces were not easily procurable, she offered to her worms the tender parts of blackberry leaves, and relates that the worms ate them greedily. She next presented to them young leaves of the elm, and reports that equal success attended this trial: encouraged by these facts, she then succeeded in causing the insects to feed on the leaves and flowers of the sweet cowslip and primrose. But meanwhile the mulberry had put forth its leaves, and having procured some of these for her brood, it was thenceforth vain to offer them any other kinds of food: all were rejected; and another proof was afforded, that the mulberry tree, which no other insect will attack, is alone adapted to the natural desires of the silkworm. Mrs. Williams records one peculiarity which discovered itself throughout her investigation; by no means could the worms be brought to touch any flower of roseate hue. Pinks, roses, sweet-williams, polyanthuses, were each in turn offered by this persevering lady, and were all rejected without hesitation. It is proper to remark, that these experiments of Mrs. Williams are not confirmed by those of any other person, but, on the contrary, that Miss Rhodes was unsuccessful in every endeavor to repeat them, and succeeded only in reconciling her silkworms to the use of lettuce and spinach. Attempts to discover a substitute for the mulberry are not entirely abandoned even at the present time. It is recorded in the Bulletin Universel, for 1829, that mademoiselle Coge of Epinal has used with success the leaves of the scorzonera (viper-grass) for the nourishment of silkworms. The silk produced by worms fed on this leaf is represented to be in no respect inferior to that from worms kept on the natural food. Notwithstanding, however, this last announcement, and the partial success so frequently recorded as attending the substitution of the lettuce, all practical cultivators of silk continue to be convinced that it would be unprofitable to feed their worms on any save their natural nourishment; and the most intelligent writers on the subject approve the practice of destroying, as useless, any worms, which through ill management may be hatched before the mulberry tree has put forth leaves sufficient for their support. Recent attempts which have been made to rear silkworms in England do not offer much encouragement to the pursuit, except as matter of amusement. Some pairs of silk stockings of good quality are to be seen in the gallery of "The National Repository," woven from silk of home production. The worms which spun this were reared by Mrs. Allen of Wandsworth, the result of whose careful observations on this subject has been obtained. The difficulty of procuring a sufficient and continuous supply of proper food was the reason why this lady was obliged to relinquish a pursuit in which she had taken much pleasure for four successive years. Mrs. Allen's testimony strongly corroborates the necessity of extreme cleanliness in preserving the health of the worms. The most scrupulous attention seems to have been paid by her to this particular, as well as to the dryness of the leaves, and the temperature of the apartment wherein the insects were reared and set to spin; and yet a very great mortality was always experienced among them, scarcely more than one in five of the worms that were hatched coming to maturity and forming their cocoons. Of these it required 1000 to furnish an ounce of reeled silk, the floss being equal to a quarter of an ounce more. The cocoons were gathered in eight days from their commencement, and in eight days more were wound off. No necessity hence arose for destroying the vitality of the insects to prevent their piercing the balls. The chrysalides being placed in bran, in due time became moths and produced eggs, each female furnishing between 300 and 400. The Spider.-Discovery by Mons. Bon.-Manner of Spiders producing their Web.-Power of producing this of various Degrees of Tenuity.Great number of Fibres composing one Filament.-Different Kinds of Threads.-Spider Bags.-Silk made from these by M. Bon.-Manner of its Preparation.-Great Comparative Advantages adduced by M. Bon.His Spider Establishment.-Investigations by Reaumur.-His Objections. -Small Produce of Silk from Spiders.-The Pinna.-Description.-Delicacy of its Threads.-Reaumur's Observations.-Spinning Organ of the Pinna.-Manner of forming its Thread.-How different from that of Land Insects.-Power of Continually producing new Threads." The Pinna and its Cancer Friend."-Nature of their Alliance.-Manner of taking the Pinna. Its Threads known to the Ancients. - Peculiar Qualities of this Material. THE useful properties possessed by the produce of the silkworm, and the value which it has acquired among civilized communities, have, at various times, led ingenious men to seek among the works of nature for other substances, which, presenting appearances analogous to that beautiful filament, might be made equally conducive to human convenience and adornment. Some species of spiders are known to possess the power of not merely forming a web, but also of spinning, for the protection of their eggs, a bag somewhat similar in form and substance to the cocoon of the silkworm. At the commencement of the last century a method was discovered in France by Monsieur Bon, of procuring silk from these spiders' bags, and its use was attempted in the manufacture of several articles. The following particulars are gathered from a disser tation published at the time by M. Bon, and also from papers on the subject inserted in the volumes of the Royal Academy for the years 1710 and 1711. Spiders are usually classed according to their difference of color, whether black, brown, yellow, &c., or sometimes by the number and arrangement of their eyes: of these organs some possess no fewer than ten, others eight, and others again six. M. Bon has, however, noticed only two kinds of silk spiders, and these he has distinguished from each other as having either long or short legs, the last variety producing the finest quality of raw silk. According to this ingenious observer, the silk formed by these insects is equally beautiful, strong, and glossy with that formed by the bombyx. The spider spins minute fibres from fine papillæ, or small nipples, placed in the hinder part of its body. These papillæ serve the office of so many wire-drawing irons, to form and mould a viscous liquor, which after being drawn through them dries on exposure to the air, and forms the silk. The celebrated naturalist M. Reaumur, who likewise bestowed considerable attention on these insects, discovered that each of their papillæ consists of a number of smaller ones, so minute as not to be discernible, and only made evident by the effects produced. If the body of the spider be pressed between the fingers, the liquor from which the threads are formed flows into the papillæ, by applying the finger against which, distinct threads may then be drawn out through the several perforations of each papillæ. These threads are too fine to be counted with any accuracy, but it is evident that very many are sent forth from each of the larger papillæ. This fact tends to explain the power possessed by the spider of producing threads having different degrees of tenuity. By applying more or fewer of these papillæ against the place whence it begins its web, the spider joins into one thread the almost imperceptible individual fila, |