Nutritional conditional mutants ofDrosophila melanogaster

Abstract
A small fraction of mutagen treated X chromosomes which would appear nonlethal in the Muller-5 test carried out on a yeast-containing medium act as lethals when tested on one or other of the defined Drosophila media. Such mutants have been termed ‘nutritional conditionals’. The three mutants obtained in this way have been characterized genetically, but have not yet been shown to act as simple auxotrophs.