CONTENTS. XI 



PAGE 



separates the Germ-shield into a Right and Left Half .Below the 

 Dorsal Farrow the Central Germ-layer parts into the Notochord 

 and the Two Side-layers. The Side-layers split horizontally into 

 Two Layers : The Skin-fibrous Layer and the Intestinal-fibrons 

 Layer. The Primary Vertebral Cords separate from the Side- 

 layers. The Skin-sensory Layer separates into Three Parts : the 

 Horny Layer, Spinal Canal, and Primitive Kidney. Formation of 

 the Coelom and the First Arteries. The Intestinal Canal proceeds 

 from the Intestinal Furrow. The Embryo separates from the Germ- 

 vesicle. Around it is formed the Amnion-fold, which coalesces 

 over the back of the Embryo, so as to form a Closed Sac. The 

 Amnion. The Amnion-water. The Yelk-sac, or Navel-vesicle. 

 The Closing of the Intestinal and Ventral Walls occasions the 

 Formation of the Navel. The Dorsal and Ventral Walls ... 274 



CHAPTER XI. 



GENERAL STRUCTURE AND ARTICULATION OF THE 

 INDIVIDUAL. 



Essential Agreement between the Chief Palingenetic Germ Processes 

 in the case of Man and in that of other Vertebrates. The Humar. 

 Body, like that of all Higher Animals, develops from Two Primary and 

 Four Secondary Germ-layers. The Skin-sensory Layer forms the 

 Horn-plate, the Medullary Tube, and the Primitive Kidneys. The 

 Middle Layer (Mesoderm) breaks up into the Central Notochord, 

 the Two Primitive Vertebral Cords, and the Two Side-layers. 

 The latter split up into the Skin-fibrous Layer and the Intestinal- 

 fibrous Layer. The Intestinal-glandular Layer forms the Epi- 

 thelium of the Intestinal Canal, and of all its Appendages. Onto- 

 genetic and Phylogenetic Fission of the Germ-layers. Formation 

 of the Intestinal Canal. The Two-layered Globular Intestinal 

 Germ-vesicle of Mammals represents the Primitive Intestine. 

 Head Intestinal Cavity, and Pelvic Intestinal Cavity. Mouth 

 Groove and Anal Groove. Secondary Formation of Mouth and 

 Anus. Intestinal Navel and Skin-navel. Movement of the 

 Primitive Kidneys from the Outside to the Inside. Separation of 

 the Brain and Spinal Marrow. Rudiments of the Brain-bladders. 

 The Articulation or Metameric Structure of the Body. The 

 Primitive Vertebrae (Trunk- Segments, or Metamera). The Con- 

 struction and Origin of the Vertebral Column. Vertebral Bodies 

 and Vertebral Arches. Skeleton-plate and Muscle-plate. Forma- 



