Leading on from Pseudo_Intellectual's post...
You mentioned the worms being cut in half and memories being retained. I have in front of me a book, containing part of a report on an experiment performed by Thompson and McConnell whilst they were studying at The University Of Texas.
The experiment consisted of teaching the flatworms to avoid an electric shock by swimming towards a light source.
The worms were then chopped in half and left to regrow heads and tails, as appropriate. It was found that all the worms retained the skill of avoiding the shocks.
This introduced the idea of memory molecules, particles that exist in multiples and can migrate.
The experiment was recreated in 1960, only this time the worms that had learned to swim to the light were chopped up and fed to another group of worms, then tested with a control group. The cannibal worms retained the memories, while the control group showed no evidence of immediate intelligence.
As requested by bindlenix, the book that this is from is... "The Odd Body" by Dr Stephen Juan
ISBN 0-207-18816-5