X TABLE OF CONTENTS. 



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

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

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

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

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

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

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

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

 i66. The columella, 166, 167. Tlie vascular system, 167 — 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, 173. 

 CEsophagus and stomach, 173. The intestine, 174. The postanal 

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

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

 body, i8i, 182. The spleen, 182. The growth and blood-vessels of the 

 allantois, 182 — 184. The mesoblast, 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 Chauges which take place on the Foueth Day, pp. 195 — 231. 



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



The vitelline duct, 196. 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- 

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

 the mesoblastic somites, 204 — 212. The membranous vertebral 

 column, 205. The secondary segmentation of the vertebral column 

 and formation of the permanent vertebrte, 205 — 207. Recapitulation, 

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

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



Wolffian body and duct, 212—214. The Mullerian duct, 214 21S. 



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

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

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

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

 229, 230. Summary, 230, 231. 



