X TABLE OF CONTENTS. 



of the auditory involution, 157. The otic vesicle, 157. The mem- 

 branous labyrinth, 158, 159. The osseous labyrinth, 159, 160. Com- 

 parison of ear with eye, 160, 161. The organ of smell, 161, 162. 

 The olfactory lobes and nerves, 162. The visceral arches and visceral 

 clefts, 162—167. Superior maxillary, and fronto-nasal processes, 

 164, 165. Fate of first visceral cleft, 165, 166. The meatus audi- 

 torius extemus, 166. The tympanic membrane, 166. The Eustachian 

 tube and tympanic cavity, 165, 166. The fenestra ovalis and rotunda, 

 166. The columella, 166, 167. The vascular system, le^ — 170. The 

 aortic arches, 167. Changes in the heart, 167, 168. The venous 

 system, 169, 170. The meatus venosus, cardinal veins and ductus 

 Cuvieri, 169, 170. The alimentary canal, 171 — 185. Folding in of 

 the splanohnopleure, tail-fold, 171, 172. The mesentery, 172, 1715. 

 (Esophagus and stomach, 173. The intestine, 1J4. The postanal 

 gut, neurenteric canal and proctodseum, 174 — 176. The lungs, 

 176 — 178. The liver, 178 — 181. The pancreas, 181. The thyroid 

 body, 181, 182. The spleen, 182. The growth and blood-vessels of the 

 aUantois, 182 — 184. The mesohlast, 185 — 193. The muscle-plates, 

 186 — 189. The intermediate cell-mass and Wolffian body, 189 — 193. 

 A typical Wolffian tubule, 193. Change of position of Wolffian duct, 

 193. Summary, 193, 194. 



CHAPTER VII. 

 The Changes which take place on the Fourth Day, pp. 195 — 231. 



Appearance on opening the egg, 195. Growth of amnion, 195, 196. 

 The vitelline duct, ig6. Increase of cranial flexure and tail-fold, 196 — 

 198. The first appearance of the limbs, 198. The growth of the 

 brain, 200. The face, 202. Changes in the nasal pits, 202. The sto- 

 modteum and mouth, 202, 203. The cranial nerves, 203. Changes in 

 the mesoilastic somites, 204 — 212. The membranous vertebral 

 column, 205. The secondary segmentation of the vertebral column 

 and formation of the permanent vertebrae, 205 — 207. Becapitulation, 

 207, 208. The changes in the notochord, 208 — 211. Ossification of 

 vertebrsB, 209, 210. The changes in the muscle plates, 211, 212. 

 Wolffian body and duct, 212—214. The Mullerian duct, 214 — 218. 

 The kidney and ureter, 218 — 220. The ovaries and testes, 220 — 223. 

 Fate of the embryonic urinogenital organs, 223, 224. Chadges in the 

 arterial system, 224 — 226. Changes in the venous system ; veins of 

 the liver, 226 — 229. Changes in the heart ; the ventricular septum, 

 229, 230. Summary, 230, 231. 



