Screening for new meiotic mutants on the X chromosome. Shown is a simple example of a forward genetic screen for new meiotic mutations on the X chromosome. Most commonly, females homozygous for the mutagenized chromosome have been tested by scoring the level of X chromosome nondisjunction among the progeny, but autosomal nondisjunction, recombination, or cytological parameters can also be examined. For more detailed descriptions of forward genetic screens of the X chromosome, including more complicated selection-type screens, see Baker and Carpenter (1972), Liu et al. (2000), Collins et al. (2012).