The work of Hans Driesch work was a critically important antecedent to the animal cloning experiments of the late 20th century. Driesch was born in Bad Kreuzsnach, Germany. He studied at Freiburg with August Weismann and then at Jena where he received his Ph.D. with Ernst Heinrich Haeckel in 1889. Prior to Driesch, another German biologist Wilhelm Roux, showed that a half embryo develops when one cell of a two cell frog embryo is killed. This suggested that the embryo is a mosaic and that cells develop independently. Further, it implied that the genetic material contained in the nucleus is qualitatively unequally divided. Thus, embryonic cell division would resulting in differential distribution of the genetic material. Driesch, using sea urchin eggs, obtained diametrically different results. He separated embryonic cells (blastomeres) at the two cell stage and found that each of the cells cleaved (divided), formed ciliated blastulae, and...