From the above observations, it will be plain that, when we wish to
bring a diseased organ under the influence of the _positive_ pole, we
must carefully place our electrodes so that none of the organ, or none
of the diseased part of it, shall appear on the positive[B] side of the
_central point of the circuit_; it being understood that the current
moves as nearly in direct lines as the best conducting medium will
admit. Or again, if it be desired to bring a diseased organ, or any
extended part of it, under the influence of the _negative_ pole, we must
first calculate in placing our electrodes about where the central point
will come, and then so apply them that no part of the lesion or disease
shall appear on the negative[B] side of the central point; otherwise so
much of it as lies on that side will come under the force of the wrong
pole, and thus be affected in a way the opposite of what was intended.
The characteristic influence of each pole is felt throughout its own
half of the circuit.