Fig. 1. (A) Cartoon of the head of an M. sexta caterpillar, as viewed from below. An enlargement of the maxilla (indicated with an arrow) is provided to clarify the location of the medial and lateral styloconic sensilla. This cartoon was adapted from Bernays and Chapman, fig. 3.4 (Bernays and Chapman, 1994). (B) Illustration of the tip-recording method, which was used to record excitatory responses of individual taste cells located within a taste sensillum. During a tip recording (Hodgson et al., 1955), the tip of a taste sensillum is inserted into the end of a glass recording/stimulating electrode, which is filled with a taste stimulus dissolved in an electrolyte solution (0.1 mol l^–1 KCl in deionized water). The taste stimulus solution diffuses through a pore in the tip of the sensillum and activates transduction mechanism(s) on the distal end of a taste cell's dendritic process; the electrode detects the ensuing action potentials. For clarity, only one taste cell is indicated. Note that the taste cell's axonal process projects directly to the central nervous system without synapsing.