Research was carried out into the ionic aspects of depolarization potentials produced inHelix lucorum neuron RPa4 by injecting three cholinomimetics into the soma: acetylcholine, nicotine, and muscarine. Substances were used suppressing Na+, K+, Ca2+, and Cl− conductance at the membrane. Acetylcholine brought about increased Na+, Ca2+; and Cl− conductance. As the choline component was only slight, due to the similarity of membrane and resting potential for chloride, it might be deduced that the prevailing response to acetylcholine is associated with chemically controlled input of Na+ and Ca2+ into the cell. Nicotine and muscarine induced mainly sodium and calcium conductance respectively.