G. Christopher Davies, The Swan and her crew, or the adventures of three young naturalists and sportsmen on the broads and rivers of Norkfolk, Londres, Frederick Warne, 1889, p. 168-169.
Crawling along the bottom were umbers of caddis-worms in tube-like cases made of sticks and stones. Inside these cases are the plump white grubs which turn into flies.
« Where the bottom is gravelly these caddis-worms make their cases of little stones », said Frank.
« Yes, and I read the other day that an experiment had been tried by some one, who took some out of their nests and put them into aquarium with some finely-broken glass of different colours, and the caddis-worms made their cases of this broken coloured glass, and very pretty they looked. »
« Their own bodies must supply the glue which fastens the piece of gravel or glass together ? »
« Yes, it does. »