C. B. Bridges' repeat hypothesis and the nature of the gene

In producing the definitive maps of the giant salivary gland chromosomes of Drosophila melanogaster, C. B. Bridges, 1935, interpreted certain structures as tandem gene duplications that had become established in the species. Bridges had, in fact, provided a cytological basis for challenging the concept of multiple allelism that had dominated research on the nature of the gene for nearly 40 years.