Morgan was a supporter of de Vries's mutation theory and was hoping to gather evidence in favor of it when he started working with the fruit fly Drosophila melanogaster in his lab in 1907.
Morgan apoiaba a teoría das mutacións de de Vries e esperaba reunir probas no seu favor cando empezou a traballar no seu laboratorio coa mosca do vinagre Drosophila melanogaster en 1907.