Ross Harrison's experimen
Ross Harrison's experiments with one member of this class lent experimental support to the concept  of the morphogenetic field. The juvenile form of another member of this class is commonly matured with  Steinberg's solution. Shortly after fertilization, the eggs of several members of this class display a grey  crescent due to cortical rotation, which was first observed in its Rana genus. The standard reference for the developmental stages of that organism in this class is a book of Nieuwkoop and Faber. That organism  was the subject of Spemann and Mangold's organizer experiment. Due to its shorter reproductive time,  the tropicalis species has recently supplanted the laevis species of a genus in this class. For 10 points, identify this class that includes the model organisms Ambystoma mexicanum, also known as the axolotl, and Xenopus laevis, also known as the African clawed frog.
Ross Harrison's experiments with one member of this class lent experimental support to the concept  of the morphogenetic field.