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