A new eye phenotype in Drosophila melanogaster expressed only at temperatures above 25 degrees C.

F L I E S expressing a new eye abnormality (scarp, see below) were observed during the summer of 1960 in a "wild" Cockaponsett stock. A review of environmental conditions showed that the temperature had risen to 30°C on each of several days before the abnormal eyes were detected. Some of the abnormalities resembled certain expressions of known mutants such as Lobe eyes and tumorous head. Lobe eyes are reduced and flattened anteriorly, whereas the new abnormal eye usually is not reduced, but it flattened ventrally. The tumorous head phenotype is characterized by abnormal growths throughout the entire head region, but the new abnormality is almost entirely restricted to the eyes. The present study was undertaken to determine whether the new abnormality was inherited and to determine the effects of temperature upon its expression.