But one of the most surprising

Anonyme, Compte rendu du livre The Passions of Animals Edward P. Thompson. Chapman & Hall. Londres 1851, New York, The American Whig Review, 1852, p. 160.

« The caddis worms, or larvae of the four-winged flies in the order Trichoptera, live under water, where they construct for themselves movables habitations of various materials, according to their habits or to the substances most conveniently procured, such as sans, stones, shells, wod, and leaves glued together longitudinally, but leaving an aperture sufficiently large for the inhabitant to put out its head and shoulders when on the look-out for food; another employs pieces of reed, grass, straw, or wood, carefully jopined and cemented together; another makes choice of the tiny shells of young fresh-water mussels and snails to form a movable grotto; and as these little shells are for the most part inhabited, he keeps the poor animals close prisoners, and drags them along with him. But one of the most surprising instances of their skill occurs in the structures of which small stones are the principal materials. The problem is to make a tube about the width of the hollow of a wheat-straw, and equally smooth and uniform; and as the materials are small stones, full of angles and irregularities, the difficulty of performing this problem will appear to be considerable, if not insurmountable: yet the little architects, by patiently examining their stones, and turning them around on every side, never fail to accomplish their plans. This however, is only part of the problem, which is complicated with another condition, namely, that the under surface shall be flat and smooth, without any projecting angles which might impede its progress when dragged along the bottom of the rivulet where it resides. In some instances, where thses little cases are found to possess too great a specific gravity, a bit of light wood or a hollow straw is added to buoy them up. »