Page:The Life of the Spider.djvu/209

 formed of compact white satin, an insuperable barrier. It opens into a round orifice wherein is bedded a lid of the same material, through which the feeble beasties would be incapable of passing. It is not a porous felt, but a fabric as tough as that of the sack. Then by what mechanism is the delivery effected?

Observe that the disk of the lid doubles back into a short fold, which edges into the orifice of the bag. In the same way, the lid of a saucepan fits the mouth by means of a projecting rim, with this difference, that the rim is not attached to the saucepan, whereas, in the Epeira's work, it is soldered to the bag or nest. Well, at the time of the hatching, this disk becomes unstuck, lifts and allows the new-born Spiders to pass through.

If the rim were movable and simply inserted, if, moreover, the birth of all the family took place at the same time, we might think that the door is forced open by the living wave of inmates, who would set their backs to it with a common effort. We should find an approximate image in the case of the saucepan, whose lid is raised by the boiling of its contents. But the fabric of the cover is one with the fabric of the bag, the two are closely