plant galvanometer

[Simon Penny]

I would be very grateful for any leads, advice, references on the
subject of measuring plant voltages:

In particular, I'd like to see:
    schematics/designs for the sensing hardware
    discussion of parameters, variables, most galvanomically active
plant subjects.

Any suggestions concerning other (simple) techniques for real-time
feedbck from plants would be appreciated.

Also, any recommendations of more appropriate net-sites. 

Please reply to my email address, as I am outside the discipline and
don't read this listing regularly,

thnakyou

simon penny