I could not leave my readers with more fitting words. In 1894, Bateson had published a volume titled Materials for the Study of Variation. It was mainly intended as a contribution to evolutionary biology, as revealed by the subtitle: Treated with Especial Regard to the Discontinuity in the Origin of Species. Variation, however, deserves to be studied in all provinces of the life sciences, especially those in which too strict a focus on a bunch of model species is the premise for incautious haste to proclaim general principles. As we have seen in this book, this is often the case with developmental biology.