Alan,
Interesting observation about the spinner with one wing stuck in the film as being selected over the fully spent fly. Vince Marinaro tied some of his spinners with a slightly V'd wing so that, according to Vince, they would roll from one wing to the other and thus be more attractive to the trout.

Not likely I'll ever get acroos the Pond to fish this hatch but it looks like fun.

The Chronicler