VI CONTENTS. 



PAGE 



Reciprocal Action Of different parts of the Retina 226 



Movements of the Eye 228 



Simultaneous Action of the two Eyes 228 



CHAPTER XX. 



GENERATION AND DEVELOPMENT 234 



Generative Organs of the Female 234 



Unimpregnated Ovum 236 



Discharge of the Ovum 239 



Menstruation 240 



Corpus Luteum , 243 



IMPREGNATION OP THE OVUM 246 



Male Sexual Functions 246 



Structure of the Testicle 246 



Spermatozoa 247 



The Semen ' 251 



DEVELOPMENT 252 



Changes of the Ovum up to the Formation of the Blastoderm . . . 252 



Segmentation of the Ovum ......... 253 



Fundamental Layers of the Blastoderm: Epiblast; Mesoblast; Hypoblast. 255 



First Rudiments of the Embryo and its Chief Organs .... 256 



Fatal Membranes 261 



The Umbilical Vesicle 262 



The Amnion and Allantois 262 



TheChorion . . 264 



Changes of the Mucous Membrane of the Uterus and Formation of the 



Placenta 266 



DEVELOPMENT OF ORGANS 270 



Development of the Vertebral Column and Cranium .... 270 



" Face and Visceral Arches . . . . . . 273 



" Extremities 275 



" Vascular System 276 



Circulation of Blood in the Foetus 286 



Development of the Nervous System 287 



" Organs of Sense 291 



" Alimentary Canal 295 



" Respiratory Apparatus 298 



" " Wolffian Bodies, Urinary Apparatus, and Sexual 



Organs 298 



CHAPTER XXI. 



ON THE RELATION OF LIFE TO OTHER FORCES , 306 



