A fly is secured on a glass slide, using a drop of hot myristic acid. Two syringes are filled either with fructose in water (3 %) or quinine. When a leg on the left side is touched with the fructose solution, the fly extends its proboscis to feed from it. When one leg is touched with fructose and the other with quinine, the proboscis extension reflex is inhibited.
This indicates that neurons on the leg touched by quinine, are counteracting the stimulatory effect of the neurons excited by fructose on the other leg.