In direct opposition to the effort of man

Delabere P. Blaine, An Encyclopedia of Rural Sports, Londres, Longmans Green, 1870, p. 1012.

The process of forming the caddis case appears to commence thus: the animal spins a silken lining through the interstices of which it throws out an animal glue serving as the mortar for cementing the masonry of this outer covering. In the selection of the materials of their residence, caddies, directed by an unerring instinct, evince not only mich skill, but also apparent forethought. If they occupy rivulets or running brooks, they give solidity and weight to the structure of their dwellings. If their situation be in stagnant waters, the lighter materials of vegetable origin are used ; and if, accidentally, the medium they inhabit becomes changed and forms a current, they attach to their frail and light dwelling a stone as an anchor. It may be observed, that the architectural process of the caddis or case-worm larva, are in direct opposition to the effort of man, who commences his building from without by raising a superstructure according to his means, intented not only to afford himself comfort, but also to excite admiration in those around him. Our minute builder, on the contrary, commences his operation on the internal furniture of the mansions, and the limits of his walls are the lines of demarcation of his own person. In this adaptation all the species are agreed ; but in the outline of the domicile, and the component materials of it great diversities are manifest.