Contents 



Preface vii 



Acknowledgments ix 



Orientation xiii 



Part I 



The Period of Preparation 



1 . The Testis and Its Relation to Reproduction 3 



2. The Vertebrate Ovary and Its Relation to Reproduction 52 



3. The Development of the Gametes or Sex Cells 112 



Part II 

 The Period of Fertilization 



4. Transportation of the Gametes (Sperm and Egg) from the Germ 

 Glands to the Site where Fertilization Normally Occurs 177 



5. Fertilization 210 



Part III 

 The Development of Primitive Embryonic Form 



6. Cleavage (Segmentation) and Blastulation 279 



7. The Chordate Blastula and Its Significance 340 



8. The Late Blastula in Relation to Certain Innate Physiological 

 Conditions: Twinning 373 



9. Gastrulation 388 



10. Tubulation and Extension of the Major Organ-forming Areas: 

 Development of Primitive Body Form 454 



11. Basic Features of Vertebrate Morphogenesis 516 



Part IV 

 Histogenesis and Morphogenesis of the Organ Systems 



12. Structure and Development of the Integumentary System 555 



13. Structure and Development of the Digestive System 596 



14. Development of the Respiratory-buoyancy System 634 



15. The Skeletal System 653 



xi 



