Proof that the genes are arranged in a linear sequence along the chromosome. Sturtevant determined the relative positions of six genetic factors on a fly’s chromosome by creating a process called gene mapping. The work paved the way for the construction of chromosome maps for other species besides Drosophila.

Summarizes the major early findings of Morgan’s Drosophila research group, which based its research on the rapidly reproducing small vinegar fly, Drosophila melanogaster, often called the fruit fly. This epoch-making book presented evidence that genes were arranged linearly on chromosomes, and that the Mendelian laws could be shown to be based on observable events occurring in cells. The group also showed that heredity could be studied rigorously and quantitatively. Morgan was awarded the Nobel Prize for Physiology or Medicine in 1933.

Order of authorship in the original publication: Morgan, Sturtevant, Muller, Bridges.
Digital facsimile from Biodiversity Heritage Library at this link.