Johannes Holtfreter, an important experimental embryologists of the twentieth century, was best known for his studies of the embryonic organizer and embryonic induction. Although all of his work was done with the classic system of embryological research, the amphibian embryo, Holtfreter was able to see the embryo in terms of complex interactions between cells, especially the cells surrounded the organizer. His research provided insights into modern issues of cell competence, inductive signals, and the ways in which signals from the organizer provoked developmental phenomena in sensitized cells.

Holtfreter was born in Richtenberg, a small town in Pomerania, Germany. As a boy, Holtfreter enjoyed collecting and drawing animals and butterflies. His family moved to Stralsund on the Baltic Sea at the start of World War I. Despite the disruptions caused by the war, Holtfreter was able to study at the local Realgymnasium. His interest in field biology grew, although...