Electric Fields Rewrite the Body Plan — Bioelectricity Nexus

An interactive re-creation of the classic Marsh & Beams (1952) experiment showing that an externally applied DC electric field can redirect anterior–posterior patterning in regenerating planaria (Dugesia tigrina).

Marsh & Beams (1952)

Trunk fragments of the flatworm were regenerated inside an applied DC electric field. Depending on the field's orientation and strength, the fragment regenerated normally, formed two heads, or underwent complete polarity reversal.

  • Weak or aligned fields: normal regeneration — a head at the anterior end and a tail at the posterior end
  • Moderate opposing field: a two-headed (bipolar) worm, with a head where a tail should be
  • Strong opposing field: complete polarity reversal — the anterior–posterior axis inverts entirely

    • Field strength, not current density

    In a companion study, Dimmitt & Marsh varied the medium's specific resistance to distinguish electric-field strength from current density. Over the tested range, regenerative polarity tracked the potential gradient rather than the current density, identifying the applied electric field as the decisive control parameter.