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OUTLINES OF 



CHORD ATE DEVELOPMENT 



CHAPTER I 

 THE DEVELOPMENT OF AMPHIOXUS 



PAGE 



INTRODUCTION 2 



I. THE GERM CELLS AND THEIR PRODUCTION 4 



II. THE EMBRYONIC PERIOD 9 



A. FROM FERTILIZATION TO THE TIME OF. HATCHING ... 9 



1. Fertilization 9 



2. Cleavage 11 



3. Gastr ulation 15 



4. The Formation of the Central Nervous System .... 20 



5. The Formation of the Notochord 23 



6. The Formation of the Mesoderm and Enteroccels ... 24 



B. FROM HATCHING TO THE FORMATION OP THE MOUTH . 27 



1. The Central Nervous System 27 



2. The Notochord 28 



3. The Mesodermal Somites and Ccelom 29 



4. The Enteron and Its Appendages 33 



III. THE LARVAL PERIOD 37 



1. The Central Nervous System 37 



2. The Gill Slits 39 



3. The Club-shaped Gland 43 



4. The Endostyle 43 



5. The Mouth and Associated Structures 44 



6. The Preoral Pit and Its Derivatives 44 



7. The Blood-vessels 46 



8. The Atrium 46 



9. Larval Asymmetry 49 



10. The Mesodermal Somites 51 



11. The Nephridia 53 



12. The Larva at the Critical Stage 54 



IV. THE ADOLESCENT PERIOD 55 



1 



