J. A. Partridge, Everyday Science (for Grade 7), Toronto & Vancouver, J. M. Dent, 1940, p. 352-353
These animals carry their homes with them as do snails and clams. And a funny home it has, too ! Probably you collected some of these homes with the dead leaves from the side of te creek. They look like bits of rubbish walking in the bottom of your jar (Fig. 328)
This Will Be Fun.
Take a caddis-worm from your jar. Carefully separate the tiny sticks and pieces of leaves which make its home. Put the worm itself into a tumbler of clean water and observe the tiny gills at the end of its body . Cut some celluloid or mica into pieces and put them into the dish. Watch the worm build a new transparent home by cementing the pieces together with its saliva.
Watch the worm reaching out from its case to crawl (Fig ; 335, A). It hangs on by little hooks at its tail. If a fish approaches, it suddenly darts in.
When full, grown the worm sticks its case to something (Fig. 335, B) in the water and seals, the open end, leaving only a little opening through which water may brin git oxygen for brething