Retraction: Oct-3 is a maternal factor required for the first mouse embryonic division

preformationist chains. As the book describes, these philosophical arguments continued with the more well-known debates in developmental biology at the turn of this century-namely wholism, vitalism, and epigenesis. Thus, this is a very illuminating book for all developmental biologists. It reminds us that regeneration studies were for two hundred years the driving force in developmental biology, and the famous experiments of Roux, Dreisch, and Spemann were not performed independently but were seen as “regeneration” experiments. Indeed, all the concepts currently used in development, such as polarity, concentration gradients, thresholds, etc., arose from regeneration studies. Let us hope that the two fields will in the future become equal partners again and books such as Dinsmore’s may play some part in that.