First published in 1909 in La Cellule, F. A. Janssens's "The chiasmatype theory. A new interpretation of the maturation divisions" proved controversial and was for several decades resisted by many geneticists and cytologists. In this month's Perspectives, Koszul et al. revisit Janssens's findings and the surrounding controversies. Here, translated for the first time in English, GENETICS republishes the original Janssens's article. The article is presented as closely as possible to the original publication's format and style.(2) GENETICS wishes to thank Romain Koszul and Denise Zickler for their labors in presenting the scientific community with this new translation.