By the swelling crests,

on dunes rolling with bushels of gravel,

you plucked out a single pebble—  

a clattering avalanche tumbled

down thereafter—and lifted a finger to

meticulously trace the edge in a neverending elliptical.

the action potential is the electrical impulse

along the membrane of a nerve cell.

You passed the rock from hand to hand,

gauging its aerodynamic potential, brought it up

to eye its thickness, and then bent down

so my hand could run along its span.  

The myelin sheath covers axons, the long thin projections

from the body of a neuron, and its gaps

are the nodes of Ranvier.

The undefeated champion pebble skipper

of the neighborhood, you boasted—

but rather than settling on some withering laurels,

you flicked your wrist out to the sea yet again and

watched as it bounced up and down, far

out of reach, until it gave a final dip to the sea,

never to be seen again.

Saltatory conduction, from the Latin saltare, to dance, is the propagation of

action potentials along myelinated axons from one node of Ranvier to the next,

increasing the conduction velocity.

It’s been years now, and I’ve never once

replicated anything near your

infamous 8-bounce skips.  Perhaps

my chance is gone—I’ve swapped out

rocks for books, and a cramped Labour Day trip

to the beach will not yield

an epiphany.  But if forging past the iconic 2 am languor

concedes nothing else, at least

now each time a pebble bobs over the water,

I see the action potential skip across the length of the axon.

Axon, ax off, waxing and

waning.

Striding across time like stones, islands, the backs

of monstrous ancient turtles, zaps of electricity,

and nodes, like the nodes of time, the isles of Ranvier.

Saltatory conduction spinning out of control

before it reaches its destination at the synapse—

passing on to the next neuron and leaving

the original forever.

Give it a few more years though,

and I have a feeling that pebble

might just wash up on shore.