Females with recessive mutation crossed with wild-type males would yield the same phenotype as the wild-type, and any observable change to the phenotype would indicate that a mutation induced by the mutagen has occurred.
As femias con mutacións recesivas cruzadas con machos de tipo salvaxe terían o mesmo fenotipo que o tipo salvaxe, e calquera cambio observable no fenotipo indicaría que ocorreu unha mutación inducida polo mutáxeno.