▁for ▁example , ▁whether ▁the ▁spec imen ▁is ▁hom o zy got ic ▁or ▁heter o zy got ic ▁results ▁in ▁a ▁dark er ▁or ▁less ▁dark ▁appearance . ▁This ▁gen etic ▁mut ation ▁is ▁x - link ed ▁re cess ive . ▁b w : ▁brown - ▁The ▁brown ▁eye ▁mut ation ▁results ▁from ▁p ter id ine ▁( red ) ▁p ig ments ▁in ability ▁to ▁be ▁produced ▁or ▁synth es ized , ▁due ▁to ▁a ▁point ▁mut ation ▁on ▁chrom os ome ▁II . ▁When ▁the ▁mut ation ▁is ▁hom o zy g ous , ▁the ▁p ter id ine ▁p ig ments ▁are ▁unable ▁to ▁be ▁synth es ized ▁because ▁in ▁the ▁beginning ▁of ▁the ▁p ter id ine ▁path way , ▁a ▁defect ive ▁en zym e ▁is ▁being ▁c oded ▁by ▁hom o zy g ous ▁re cess ive ▁gen es . ▁In ▁all , ▁mut ations ▁in ▁the ▁p ter id ine ▁path way ▁produces ▁a ▁dark er ▁eye ▁color , ▁hence ▁the ▁resulting ▁color ▁of ▁the ▁bio chem ical ▁defect ▁in ▁the ▁p ter id ine ▁path way ▁being ▁brown . ▁m : ▁mini ature - ▁One ▁of ▁the ▁first ▁records ▁of ▁the ▁mini ature ▁mut ation ▁of ▁wings ▁was ▁also ▁made ▁by ▁Thomas ▁H unt ▁Morgan ▁in ▁ 1 9 1 1 . ▁He ▁described ▁the ▁wings ▁as ▁having ▁a ▁similar ▁shape ▁as ▁the ▁wild - type ▁phen ot ype . ▁However , ▁their ▁mini ature ▁design ation ▁refers ▁to ▁the ▁lengths ▁of ▁their