weakest hunted thing occasionally succeeds in inflicting pain on its persecutor, and the small trembling mouse, unable to save itself, can sometimes make the cat shriek with paiu; but there is no weak spot in the wasp's armour, no fatal error of judgment, not even an accident, ever to save the wretched victim from its fate. And now comes the most iniquitous part of the proceeding. When the wasp has sufficiently rested after the struggle, it deliberately drags the disabled spider back into its own hole, and, having packed it away at the extremity, lays an egg alongside of it, then, coming out again, gathers dust and rubbish with which it fills up and obliterates the hole; and, having thus concluded its Machiavellian task, it flies cheerfully off in quest of another victim.
The extensive Epeira family supply the mason-wasps and other spider-killers with the majority of their victims. These spiders have soft, plump, succulent bodies like pats of butter; they inhabit trees and bushes chiefly, where their geometric webs-betray their whereabouts; they aré timid, comparatively innocuous, and reluctant to quit the shelter of their green bower, made of a rolled-up leaf; so that there are many reasons why they should be persecuted. They exhibit a great variety of curious forms; many are also very richly coloured; but even their brightest hues--orange, silver, scarlet --have not been given without regard to the colouring of their surroundings. Green-leafed bushes arc frequented by vividly green Epeiras, but the imitative resemblance does not quite end here. The green spider's method of escape, when the bush is
Facts and Thoughts about Spiders. 183
roughly shaken, is to drop itself down on the earth, where it lies simulating death. In falling, it drops just as a green leaf would drop, that is, not quite so rapidly as a round, solid body like a beetle or spider. Now in the bushes there is another Epeira, in size and form like the last, but differing in colour; for instead of a vivid green, it is of a faded yellowish white--the exact hue of a dead, dried-up leaf. This spider, when it lets itself drop--for it has the same protective habit as the other--falls not so rapidly as a green freshly broken off leaf or as the green spider would fall, but with a slower motion, precisely like a leaf withered up till it has become almost light as a feather. It is not difficult to imagine how this comes about: either a thicker line, or a greater stiffness or tenacity of the viscid fluid composing the web and attached to the point the spider drops from, causes one to fall slower than the other. But how many tentative variations in the stiffness of the web material must there have been before the precise degree was attained enabling the two distinct species, differing in colour, to complete their resemblance to falling leaves--a fresh green leaf in one case and a dead, withered leaf in the other!
The Tetragnatha--a genus of the Epeira family, and known also in England--are small spiders found on the margin of streams. Their bodies are slender, oblong, and resembling a canoe in shape; and when they sit lengthwise on a stem or blade of grass, their long, hair-like legs arranged straight before and behind them, it is difficult to detect them, so closely do they resemble a discoloured stripe on the herbage. A species of Tetragnatha
184 The Naturalist in La Plata.
with a curious modification of structure abounds on the pampas. The long leg of this spider is no thicker than a bristle from a pig's back, but at the extremity it is flattened and broad, giving it a striking resemblance to an oar. These spiders are only found in herbage overhanging the borders of streams: they are very numerous, and, having a pugnacious temper, are incessantly quarrelling; and it frequently happens that in these encounters, or where they are pursuing each other through the leaves, they drop into the water below. I believe, in fact, that they often drop themselves purposely into it as the readiest means of escape when hard pressed. When this happens, the advantage of the modified structure of the legs is seen. The fallen spider, sitting boat-like on the surface, throws out its long legs, and, dipping the broad ends into the water, literally rows itself rapidly to land.
The gossamer-spider, most spiritual of living things, of which there are numerous species, some extremely beautiful in colouring and markings, is the most numerous of our spiders. Only when the declining sun flings a broad track of shiny silver light on the plain does one get some faint conception of the unnumbered millions of these buoyant little creatures busy weaving their gauzy veil over the earth and floating unseen, like an ethereal vital dust, in the atmosphere.