This is the first detailed paper on Paramecium galvanotaxis (note that as I am not a German speaker, this review is based on an automatic translation). When paramecia are subjected to a continuous electrical field of sufficient amplitude (roughly 500 V/m), they align with the field, facing the cathode. Then they swim towards the cathode, at reduced speed (roughly 500 µm/s in this paper). This phenomenon was known before, but here Ludloff describes how it happens through the effect of the field on the cilia. When the electrical field is switched on, cilia on the cathode side reverse. Thus, if the cell is orthogonal to the electrical field, then the cilia on the anode side make that side move forward while the cilia on the cathode side make that side move backward. As a result, the cell turns towards the cathode. When facing the cathode, the posterior side swims forward and the anterior side swims backward, but with reduced strength. Therefore, the cell swims towards the cathode at reduced speed.

This phenomenon could not be explained at that time, but it is now understandable based on the electrophysiology of Paramecium. The electrical field produces an extracellular potential that is more negative on the cathode side than on the anode side. This makes the cathode side depolarized and the anode side hyperpolarized. Depolarization triggers the reversal of cilia, while hyperpolarization makes the cilia beat faster.