SPIDER’S NEST LAID OPEN.
The great obstacle which prevented the establishment of any considerable manufacture from these spiders’ bags, was the difficulty of obtaining them in sufficient abundance; but M. Bon, who was enthusiastic respecting the value of his discovery, fancied that he could easily overcome this obstacle, and at first his efforts appeared remarkably successful. He formed a large spider establishment, which, for a time, was very prosperous. Having ordered all the short-legged spiders (which are the most industrious spinners) to be collected for him by persons employed for the purpose, he enclosed them in paper boxes, with pin-holes pricked in them to admit the air to the prisoners. The insects were regularly fed with flies, and prospered well on their diet. In due time most of them laid their eggs, and spun their silken bags. M. Bon affirmed that each female produced from six to seven hundred eggs, whereas the silkworm moth lays only about one hundred. He also stated, that out of seven hundred or eight hundred young spiders which he kept, scarcely one died in a year; while of one hundred silkworms, not forty lived to form their cocoons.
These favourable statements led the Royal Academy of Paris to take the subject into consideration, and Réaumur was appointed to inquire into the merits of the new scheme. This careful inquirer found many serious obstacles in the way of such establishments. The fierceness of spiders, and their propensity to destroy each other, were noticed as unfitting them to be bred and reared together. On distributing about five thousand spiders in cells, in companies of about fifty or a hundred, it was found that the larger spiders quickly killed and ate the smaller, until there were only one or two occupiers of each cell. The silk of the spider was also found inferior in lustre and strength to that of the silkworm, and had the disadvantage of being incapable of winding off the ball, but must necessarily be carded.
GARDEN SPIDER—(Natural Size.)
Indeed, it could require no very great consideration to decide, that spiders’ silk, when compared with that of the silkworm, was vastly inferior for manufacturing purposes, though employed in many useful and highly ingenious ways by the insect itself. A few of these we must not omit to notice. Every one must have seen the common garden spider (Epeira diadema) suspended by its silken rope, or forming its beautiful web; but every one is not aware that that silken rope is made up of a multiplicity of threads, and that when the spider attaches the rope to any object by pressing her spinneret against it, she spreads out these threads over an area of some diameter, thus securing a much greater degree of strength than could be gained by merely fixing her thread to one point. This contrivance may be seen best when the threads are attached to a black object. Under the microscope they appear thus:—
SPIDER’S METHOD OF ATTACHING HER THREAD.
The uses of silk in the webs and nests of common spiders are too obvious to be dwelt on, but there is a most clever and surprising adaptation of the same material by several foreign species of spider which must be briefly stated. In the Ionian islands, and also in the West Indies, there are found certain spiders, commonly known as trap-door spiders, which make a cylindrical nest in the earth, and cover the entrance with a door of their own construction, framed of alternate layers of silk and earth, and fastened to the opening by a hinge of stout silk. These spiders also line their nests throughout with numerous layers of silken web to the thickness of stout cartridge paper, and finish it with the greatest care. This beautiful lining is yet further strengthened in particular parts, where the nest is likely to be exposed to danger. But the greatest amount of skill and care is bestowed upon the trap-door and its silken hinge. This door is about the eighth of an inch thick, rough on the outside, not much unlike an oyster shell, which it also resembles in being thick and strong near the hinge, but thinner towards the circumference. The breadth of this hinge is various, but sometimes it is very considerable, as shown in the accompanying figure. It also possesses great elastic force, so that on being opened, it closes again of itself. This is principally accomplished by a fold or doubling of the web, at each end of the hinge, which permits the door to be opened nearly to a right angle with the aperture, but no farther, unless violence be used. The under side of the door is perfectly smooth and firm, being shaped so as to fit accurately, and yet to offer no resistance when pushed open by the insect.
