The Naturalist in La Plata eBook

to swing himself from branch to branch, and finally, to escape from an enemy or in pursuit of his prey, he would be able by means of his cord to drop himself with safety from the tallest trees, or fly down the steepest precipices.  He would coil up his cord to make a bed to lie on, and also use it for binding branches together when building himself a refuge.  In a close fight, he would endeavour to entangle an adversary, and at last he would learn to make a snare with it to capture his prey.  To all these, and to a hundred other uses, the spider has put his web.  And when we see him spread his beautiful geometric snare, held by lines fixed to widely separated points, while he sits concealed in his web-lined retreat amongst the leaves where every touch on the far-reaching structure is telegraphed to him by the communicating line faithfully as if a nerve had been touched, we must admire the wonderful perfection to which he has attained in the use of his cord.  By these means he is able to conquer creatures too swift and strong for him, and make them his prey.  When we see him repairing damages, weighting his light fabric in windy weather with pebbles or sticks, as a fisher weights his net, and cutting loose a captive whose great strength threatens the destruction of the web, then we begin to suspect that he has, above his special instinct, a reason that guides, modifies, and in many ways supplements it.  It is not, however, only on these great occasions, when the end is sought by unusual means, that spiders show their intelligence; for even these things might be considered by some as merely parts of one great complex instinct; but at all times, in all things, the observer who watches them closely cannot fail to be convinced that they possess a guiding principle which is not mere instinct.  What the stick or stone was to primitive man, when he had made the discovery that by holding it in his hand he greatly increased the force of his blow, the possession of a web has been to the spider in developing that spark of intellect which it possesses in common with all animal organisms.

CHAPTER XV.

THE DEATH-FEIGNING INSTINCT.

Most people are familiar with the phenomenon of “death-feigning,” commonly seen in coleopterous insects, and in many spiders.  This highly curious instinct is also possessed by some vertebrates.  In insects it is probably due to temporary paralysis occasioned by sudden concussion, for when beetles alight abruptly, though voluntarily, they assume that appearance of death, which lasts for a few moments.  Some species, indeed, are so highly sensitive that the slightest touch, or even a sudden menace, will instantly throw them into this motionless, death-simulating condition.  Curiously enough, the same causes which produce this trance in slow-moving species, like those of Scarabseus for example, have a precisely contrary effect on species endowed with great activity.  Rapacious beetles, when disturbed, scuttle quickly out of sight, and some water-beetles spin about the surface, in circles or zigzag lines, so rapidly as to confuse the eye.  Our common long-legged spiders (Pholcus) when approached draw their feet together in the middle of the web, and spin the body round with such velocity as to resemble a whirligig.