crept along it, strengthening it as it proceeded by another thread, and thus reached the pencil.” [145] Swammerdam, part i. p. 24. [146] Intr. vol. i. p. 415. 1. “We have repeatedly witnessed this occurrence,” says Mr. Rennie, “in the fields, and when spiders were placed for experiment, as Kirby has described; but we very much doubt that the thread broken is ever intended as a bridge cable, or that it would have been so used in that instance, had it not been artificially fixed and again accidentally found by the spider. According to our observations, a spider never for an instant, abandons, the thread which she dispatches in quest of an attachment, but uniformly keeps trying it with her feet, in order to ascertain its success. We are, therefore, persuaded, that when a thread is broken in the manner above described, it is because it has been spun too weak, and spiders may often be seen breaking such threads in the process of netting their webs.” The plan, besides, as explained by these distinguished writers, would more frequently prove abortive than successful, from the cut thread not being sufficiently long. They admit, indeed, that spiders’ lines are often found “a yard or two long, fastened to twigs of grass not a foot in height.... Here, therefore, some other process must have been used[147].” [147] Kirby and Spence, vol. i. Intr. p. 416. 2. The celebrated English naturalist, Dr. Lister, whose treatise upon the native spiders of that country, has been the basis of every subsequent work on the subject, maintains that “some spiders shoot out their threads in the same manner that porcupines do their quills[148]; that whereas the quills of the latter are entirely separated from their bodies, when thus shot out, the threads of the former remain fixed to their anus, as the sun’s rays to its body[149].” A French periodical writer goes a little farther, and says, that spiders have the power of shooting out threads, _and directing them at pleasure towards a determined point_, judging of the distance and position of the object by some sense of which we are ignorant[150]. Kirby also says, that he once observed a small garden spider (_Aranea reticulata_) “standing midway on a long perpendicular fixed thread, and an appearance caught” his “eye, of what seemed to be the emission of threads.” “I,” therefore, he adds, “moved my arm in the direction in which they apparently proceeded, and, as I had suspected, a floating thread attached itself to my coat, along which the spider crept. As this was connected with the spinners of the spider, it could not have been formed” by breaking a “secondary thread[151].” Again, in speaking of the gossamer-spider, he says, “it first extends its thigh, shank, and foot, into a right line, and then, elevating its abdomen till it becomes vertical, _shoots its thread_ into the air, and flies off from its station[152].” [148] Porcupines do not shoot out their quills, as was once generally believed.