Joined them so securely

R. A. West, « My Fresh Water Aquarium », New York, The American Agriculturist for the Farm, Garden and Household, vol.20, 1861, p. 151. 

I have seen the caddis worm encase himself in his curious tube of variegated leaves, but though I have watched himclosely, I never could find out how he cut the pieces so neatly, and joined them so securely ;