Xll 



Contents 



SECTION Xll 

 METAMORPHOSIS 



631 



BY WILLIAM ETKIN 



Endocrine Control of Amphibian 

 Metamorphosis 631 



Controlling Factors in Insect Met- 

 amorphosis 637 



Mode of Action of the Metamor- 

 phic Stimulus 644 



The Activation of the Metamor- 

 phic Mechanism 653 



Cessation of Metamorphic Trans- 

 formation 656 



Summary 657 



SECTION XIII 

 REGENERATION 



Chapter 1. Invertebrates 



BY L. G. BARTH 



The Polarity Problem in Regener- 

 ation 664 



The Stimulus 666 



Potencies of Cells 667 



Correlative Differentiation 668 



Environmental Factors 671 



Metabolism and Regeneration . . . 672 



664 



Chapter 2. Vertebrates 



BY J. S. NICHOLAS 



Introduction 674 



Amphioxus and Piscine Forms . . 675 



Amphibia 677 



Endocrine Effects 685 



Reptilian Regeneration 686 



674 



Physiological Regeneration 688 



General Histology 690 



The Eye and Lens 690 



Conclusion 693 



SECTION XIV 

 TERATOGENESIS . . . 



BY EDGAR ZWILLING 



699 



Introduction 699 



The Causal Agents 700 



How Agents Produce Their Ef- 

 fects 703 



A Classification of Terata Based 



on Embryology 706 



Generalizations 710 



Resume 715 



INDEX 721 



