of gum, which is so sticky that flies caught in the web are held in this kind of birdlime until the spider is able to spring upon them.
Astronomers and microscopists make use of the strongest lines of the spider's web to form some of their delicate instruments. The thread is drawn in parallel lines at right angles across the field of the eye-piece at equal distances, so as to make a multitude of fine divisions, scarcely visible to the naked eye, and so thin as to be no obstacle to the view of the object. One means of classifying spiders is by the number of eyes they possess. These are usually two, six, or eight in number. The fangs with which the spider seizes its prey are hollow, and emit a venomous fluid into the body of the victim, which speedily benumbs and kills it. In Palestine and other countries a kind of spider is found which is entirely nocturnal in its habits, and never either hunts or feeds in daylight, but makes itself a little home, where it abides safely till sunset. It is called the trap-door spider, from the curious way in which it protects the entrance to its nest. It bores a hole in the dry earth of a bank a foot
