Characterization of the phenotype in .

In the early 20th century, Calvin Bridges and Thomas Morgan identified a number of spontaneous mutations that displayed visible phenotypes in adult flies and subsequent analysis of these mutations over the past century have provided fundamental insights into subdisciplines of biology such as genetics, developmental, and cell biology. One of the mutations they identified in 1915 was named ( ) and was described by Bridges and Morgan as having two visible phenotype characteristics in the wing. The wings were "held out at a wider angle from the body" and had a break in wing vein L3.