Study of the Passive Properties of the Axon
                    (no voltage dependent conductances)

 Many squids have giant axons that result from the fusion of a number of small axons. The giant axon runs along the dorsal side of the mantle of the squid.
The axon may be separated from the stellate ganglion and dissected out of the squid . 
The giant axon may cleaned from other nerve fibers and laid down on a recording chamber.  To study the cable properties of the axon, all the voltage dependent conductances are blocked (for example adding Tetrodotoxin (TTX) to block Na channels and 4-aminopyridine (4-AP) to block K channels)
Acurrent generator is used to inject current into the axon with an internal electrode impaled through the membrane with respect to an external electrode located far away from the injection point.
Most of the current will tend to exit the axon near the internal electrode and less towards the distal regions. After the switch is closed, the distribution of the currents as a function of time and distance are shown in the current plot.
    A plot of the membrane potential as a function of distance and time, illustates how the axon cannot propagate voltage changes with only passive membrane properties.