Page:Popular Science Monthly Volume 6.djvu/671

Rh equaled by her capacity for action when the moment arrives; and yet she is by no means hasty; as a general thing (the exceptions being due perhaps to hunger, or inexperience), the vibration of the net by an insect must be pretty decided, and at least once repeated, before the spider feels justified in springing her trap; and when, as may sometimes happen naturally, but more often through experiment, a large or fierce insect is put into the net, nothing will induce the spider to budge; she will suffer her net to be wholly destroyed rather than expose herself or her reputation (?) to a doubtful encounter. Let us suppose, however that a common fly, or a gnat, or a moth, has

 The base-line is more nearly straight, and the apex-Line is taut, the slack having disappeared.

struck the net in passing—it may have touched a single double line—but this adheres with the greatest tenacity, and is so elastic as to yield without breaking, so that each struggle involves the victim still more, and may even bring it into contact with the next interradial. As soon as the violence and repetition of the vibration indicate that an insect is really entangled, the spider awakes from her apparent apathy; she lets go with her hinder feet; the net, released from its tension, flies forward, and at the same time flaps from side to side.

The comparative inertia of the fly causes the two or three double lines next to it on the side toward the apex to be, as it were, propelled against it, and the entanglement is aided by the sidewise flapping already mentioned; as may be imagined, all this is pretty apt to involve the fly beyond the possibility of escape; but, if the spider does not feel certain of this, she creeps backward again, foot over foot, as