3. “There are many people,” says the Abbé de la Pluche, “who believe that the spider flies when they see her pass from branch to branch, and even from one high tree to another; but she transports herself in this manner; and places herself upon the end of a branch, or some projecting body, and there fastens her thread; after which, with her two hind feet, she squeezes her dugs (_spinnerets_), and presses out one or more threads of two or three ells in length, which she leaves to float in the air till it be fixed to some particular place[157].” Without pretending to have observed this, Swammerdam says, “I can easily comprehend how spiders, without giving themselves any motion, may, by only compressing their spinnerets, force out a thread, which being driven by the wind, may serve to waft them from place to place[158].” Others, proceeding upon a similar notion, give a rather different account of the matter. “The spider,” says Bingley, “fixes one end of a thread to the place where she stands, and then with her hind paws _draws out_ several other threads from the nipples, which, being lengthened out and driven by the wind to some neighboring tree or other object, are by their natural clamminess fixed to it[159].” [157] Spectacle de la Nature, vol. i. [158] Book of Nature, pt. i. p. 25. [159] Animal Biography, vol. iii. p. 475, 3d edition. Observation gives some plausibility to the latter opinion, as the spider always actively uses her legs, though not to draw out the thread, but ascertain whether it has caught upon any object. The notion of her pressing the spinneret with her feet must be a mere fancy; at least it is not countenanced by anything which we have observed. 4. An opinion much more recondite is mentioned, if it was not started, by M. D’Isjonval, that the floating of the spider’s thread is electrical. “Frogs, cats, and other animals,” he says, “are affected by natural electricity, and feel the change of weather; but no other animal more than myself and spiders.” In wet and windy weather he accordingly found that they spun very short lines, “_but when a spider spins a long thread, there is a certainty of fine weather for at least ten or twelve days afterwards_[160].” A periodical writer, who signs himself Carolan[161], fancies that in darting out her thread the spider emits a stream of air, or some subtle electric fluid, by which she guides it as if by magic. [160] Brez, Flore des Insectophiles. Notes, Supp. p. 134. [161] Thomson’s Ann. of Philosophy, vol. iii. p. 306.