This invention is a method of displaying cross-sectional images of a body so as to render the cross-sectional images more interpretable. The use of these non-halide-containing reaction products rather than chloride containing acids or alkylating agents avoids corrosion and stress cracking caused by residual inorganic chloride and other inorganic, halide-containing acids. The interfering conductors 30 and 31 are located in the cavity CAV close to the resonator DR and the switching means may or may not establish an electrical contact between the said interfering conductors 30 and 31. The developer supplying section, for supplying the developer to a photosensitive member, extends from the first side wall to the second side wall in the width direction.