 The step-by-step control of its embryogenesis was visualized by attaching fluorescent dyes of different colours to specific types of protein made by genes expressed in the embryo.A dye such as green fluorescent protein, originally from a jellyfish, was typically attached to an antibody specific to a fruit fly protein, forming a precise indicator of where and when that protein appeared in the living embryo.Using such a technique, in 1994 Walter Gehring found that the "pax-6" gene, vital for forming the eyes of fruit flies, exactly matches an eye-forming gene in mice and humans.