Abstract 1. 1. The connexions between some cell bodies and the peripheral nerves in the ganglia of Helix aspersa are described. 2. 2. The responses of the nerve cells to chemicals (acetylcholine, histamine, 5HT, 5HTP, dopamine, glutamic acid, GABA, phenylalanine and β-alanine) were tested. 3. 3. Eighteen identified cells gave consistent selective responses to the chemicals. Some were sensitive to acetylcholine, others to 5HT, or histamine, or dopamine. 4. 4. Helix brain contains material which when chromatogrammed can excite or inhibit nerve action.