Making medical doctors: science and medicine at Vanderbilt since Flexner

potency, induction, competence, and regulation were widely used as categories ofexplanation in this period. Now, when we have the technical means to investigate the inner workings of cells, this heritage is available not as a set of explanations but as a set of problems requiring solution. Probably no one did more in this vital task than Johannes Holtfreter, who receives extensive coverage in the second half of the book. His in vitro isolation experiments and his work on the regional specificity of neural induction particularly helped to define the style and standard of experimental embryology for decades to come. Hamburger's book really finishes at the Second World War, although one or two later experiments are described. The modern era, starting with Nieuwkoop's discovery of mesoderm induction, is not covered. So this is not really a book for those who want to understand amphibian development, but rather a lucid and interesting account of a critical period in scientific history. It has a special fascination because it is written by a participant who can not only tell us what happened, but also what it felt like at the time.