Review of Groups in which Self-division occurs 142 Division in Plane of Least Resistance 144 Review of Groups in which Budding occurs. Relation of Budding+ to Regeneration 149 Autotomy 150 Theories of Autotomy 155 CHAPTER IX GRAFTING AND REGENERATION Examples of Grafting in Hydra, Tubularia, Planarians, Earthworms, Tadpoles 159 Grafting Pieces of Organs in Other Parts of the Body in Higher Animals 178 Grafting of Parts of Embryos of the Frog 182 Union of Two Eggs to form One Embryo 188 CHAPTER X THE ORIGIN OF NEW CELLS AND TISSUES Origin of New Cells in Annelids 190 Origin of the New Lens in the Eye of Salamanders 203 The Part played by the “Germ-layers” in Regeneration 207 The Supposed Repetition of Phylogenetic and Ontogenetic Processes in Regeneration 212 CHAPTER XI REGENERATION IN EGG AND EMBRYO Introduction 216 Regeneration in Egg of Frog 217 Regeneration in Egg of Sea-urchin 228 Regeneration in Other Forms: Amphioxus, Ascidian, Ctenophore, Snail, Jelly-fish, Fish 236 CHAPTER XII THEORIES OF DEVELOPMENT Theories of Isotropy and of Totipotence of Cells 242 Theory of Qualitative Division of Nucleus 243 Theory of Equivalency of Cells 244 Theory of the Organized Structure of the Protoplasm 246 Theory of Cells as Units 250 Further Analysis of Theories of Qualitative Nuclear Divisions and of the Equivalency of Blastomeres 252 Driesch’s Analytical Theory, Criticism, and Later Theories of Driesch 253 Conclusions 256 CHAPTER XIII THEORIES OF REGENERATION Pre-formation Theory 260 Comparison with Growth of Crystal 263 Completing Theory 264 Theory of Formative Stuffs 265 Conclusions 269 Theory of Tensions controlling Growth 271 CHAPTER XIV GENERAL CONSIDERATIONS AND CONCLUSIONS