The sizes of drosophila are small.Their life cycles are short.They have only four pairs of chromosome.Thus, Morgan selected fruit fly as experiment materials to prove the Mendel genetic rules.

• 果蝇体小；生活周期短；只有4对染色体；且有许多特殊的性状供办识；所以摩根选择果蝇作为证明孟德尔遗传法则的实验材料.