Johannes Holtfreter to Viktor Hamburger, January 1, 1958

On Mascona. On Paul Weiss. On Trinkaus and his own research program: "I cannot see too much sense in the gospel of Trinkaus that it is most important to analyze embryonic determination in terms of cytological rather than histological events. My objection is that the embryo, my teacher, does think in terms of germ layers, even the whole organism and not primarily in terms of individual cells and their subunits." Programmatic letter, mainly on the historical intellectual roots of Holtfreter's research program.