their nest with cotton or hair. (Fig. 5.) These labors of weaving and sewing are preceded by the spinning of the thread. The bird makes it itself by twisting in its beak spiders' webs, bits of cotton, and little ends of wool. Sykes found that the threads used for sewing were knotted at the ends. It is impossible not to admire
animals who have skillfully triumphed over all the obstacles met with in the course of these complicated operations.
Gelatin Nests.—These are made by certain swallows who nest in grottoes or cliffs on the edge of the sea. After having collected from the water a gelatinous substance formed either of the spawn of fish or the eggs of mollusca, they carry this substance on to a perpendicular wall, and apply it to form an arc of a circle. This first deposit being dry, they increase it by sticking on to its edge a new deposit. Gradually the dwelling takes on the appearance of a cup, and receives the workers' eggs. (Fig. 6.) These dwellings are the famous swallows' nests so appreciated by the epicures of the extreme East, which are edible in the same way as, for example, caviare.
Constructions built of Earth—Solitary Masons.—Cer-