viii CONTENTS 



PAGE 



CHAPTER VIII. THE NERVOUS SYSTEM 233 



I. The Neuroblasts 233 



The Medullary Neuroblasts 233 



The Ganglionic Neuroblasts 236 



11. The Development of the Spinal Cord 239 



Central Canal and Fissures of the Cord 242 



Neuroblasts, Commissures, and Fiber Tracts of the Cord . 244 



III. The Development of the Brain 244 



The Telencephalon 245 



The Diencephalon 249 



The Mesencephalon 251 



The Metencephalon 251 



The Myelencephalon 252 



Commissures of the Brain 252 



IV. The Peripheral Nervous System 252 



The Spinal Nerves 252 



The Cranial Nerves 261 



CHAPTER IX. ORGANS OF SPECIAL SENSE .... 271 



I. The Eye 271 



The Optic Cup 271 



The Vitreous Humor 275 



The Lens 276 



Anterior Chamber and Cornea 278 



The Choroid and Sclerotic Coats 279 



The Eyelids and Conjunctival Sac 279 



Choroid Fissure, Pecten and Optic Nerve 281 



II. The Development of the Olfactory Organ . . . 285 



III. The Development of the Ear 288 



Development of the Otocyst and Associated Parts . . . 289 

 The Development of the Tubo-tympanic Cavity, External 



Auditory Meatus and Tympanum ...... 297 



CHAPTER X. THE ALIMENTARY TRACT AND ITS AP- 

 PENDAGES 301 



I. Mouth and Oral Cavity 301 



Beak and Egg-tooth 302 



The Tongue 305 



Oral Glands 306 



II. Derivatives of the Embryonic Pharynx 306 



Fate of the Visceral Clefts 307 



Thyroid 307 



