Robert Kemp Philip,Walks abroad and evenings at home, Londres, Houlston & Wright, 1861,

The Prince’s attention was next attracted by a singular procession of what appeared to him to be moving particles of leaves, sticks, and stones. Although they were lifeless and shapeless to the eye, there was an evident volition in their movements which indicated life within. Upon closer examination, the Prince discovered these moving bodies to consist of tubes formed of the various substances named, within each of which there existed a living creature, whose head and legs being thrust forth at will, enabled the occupant to move his tenement wheresoever he pleased.

« Who, and what are you ? » said the Prince to the foremost. «  We are Caddice-

worms,” replied the grub;” “and these are the humble abodes in which we pass the first portion of our lives. We construct them variously of bits of straw, chip, or stone; sometimes of the shells of young water molluscs, forming a sort of grotto. Most of us are herbivorous, and we think we have a right, by dwelling in these tubes, to protect ourselves from the preying propensities of various carnivorous species; but man defeats our purpose by employing us for bait, in a sport which he  calls angling. Rude as our tenements appear, they are not wholly unworthy of your examination. However rough the exterior of them may be, the inside is a smooth as glass ; and when you consider that we have to select small stones or shells, and turn them about until, getting their smooth parts to meet, we form a surface as even as the best mosaic pavement, you will give us credit for ingenuity and perseverance. Moreover, we have to construct these tubes with due regard to specific gravity of the water, and the degree of motion in the stream, of which we are inhabitants. If made of materials that are too light, they are apt to be borne away the current ; if too heavy, the labour of our motion becomes excessive, or we may be imprisoned to a spot, and unable to obtain food. In the first case,when a chip tube is too buoyant, we balance it by affixing to it a stone of sufficient weight ; but if a stone tube be found too heavy, we decrease its relative gravity by fixing to it small pieces of chip.