Having started this thread perhaps I can have the temerity to chime in
for a third time. James Mclean wrote in part:
> I have a hard time believing that a charged
>ion in my foot migrates all the way to my finger
>in the time it takes for the spark to jump to the
>doorknob. Not that I have an alternative answer,
> but it seems like something is missing here....
I agree with James, there seems to be no clear path that an ion can
follow from foot to finger. The ion might diffuse through some membranes,
but that would take a long time (although its also clear that I originally
used electron flow far too loosely).
However, assuming that the ions formed on your foot are trapped in that
region, could some inductive/polarization effect through each region of the
body due to the rearrangement of that region's ions form rather quickly and
give your finger an opposite charge without there being a trans-body ion
flow?