The homoeotic effect of “tumorous head” in Drosophila melanogaster

The morphology of the cuticular abnormalities appearing in the heads of flies from a tumorous head stock of Drosophila melanogaster was investigated. The antenna is sometimes partly replaced by leg structures, and parts of the head are frequently replaced by parts of abdominal tergites. The “rostralhaut” is sometimes replaced by genital elements, such as anal plates and clasper teeth. This is the first reported example of a homoeotic alteration to abdomen or genitalia.