In this book, one of the world's most eminent developmental biologists discusses some of the exciting new insights into how genes control development. Walter Gehring describes in vivid detail his essential contributions to the landmark discovery of the homeobox, a characteristic DNA segment found in the genes of all higher organisms from the fruitfly to humans, and he explains how this has provided the key to our modern understanding of development and evolution. The book thus becomes not only a lucid discussion of genetics but also an engaging description of the art of scientific investigation.