intro - keyed particles with path option shaping a spider web

Intro to illustrate the "path" option usage in particles system.

4 particles systems keyed two by two. Path option selected in the particles systems' "render" tab to shape a sort of spider web.

Blend file here:
https://docs.google.com/open?id=0B2BWubg0Qrg4M2pZc1ZmcTdfWGc