Abstract
1. The expressivity of curled character in Drosophila melanogaster is influenced by the environmental conditions. One of these is the nutritional condition through the larval stage: the better the nutritional condition the more typical the curled character. Another is the cultural temperature: the higher the temperature the higher the expressivity. The temperature-effective period is in the last day of the pupal stage. These properties of the curled phenotype are identical with those of Curly character, although the level of expressivity is far lower in the former.
2. When these two mimic genes are combined, the curling appearance of the flies changes increasingly; the recessive curled gene is incompletely dominant in the presence of the Curly gene.
