TABLE OF CONTENTS. XI 



CHAPTER VIII. 



THE CHANGES WHICH TAKE PLACE ON THE FIFTH DAY, pp. 232 274. 



Appearance on opening the egg, 232. The changes in the limbs, 

 233, 234. The pectoral and pelvic girdles ; the ribs and sternum, 234, 

 235. The development of the skull, 235246. The cranium, 235. 

 The parachordals and notochord, 237, 238. The trabeculse, 239 241. 

 The sense capsules, 241, 242. Membrane and cartilage bones, 242. 

 Skeleton of visceral arches, 242 245. Table of bones, 246. The 

 changes in the face, 246 251. The posterior nares, 251. Changes in 

 the spinal cord; its histological differentiation, 251 254. The central 

 canal; and the posterior and anterior fissures, 254 256. Changes 

 in the heart, 256 264. Septum in the bulbus and semilunar valves, 

 257 259. The cardiac valves, 262. The foramen ovale and Eustachian 

 valve, 262 264. The pericardial and pleural cavities, 264 269. 

 Histological differentiation and the fate of the three primary layers, 

 269273. Summary, 273, 274. 



CHAPTER IX. 



FROM THE SIXTH DAY TO THE END OF INCUBATION, pp. 275 303. 



The appearance of distinct avian characters, 275. The foetal 

 appendages during the 6th and 7th days, 276 278. During the 

 8th, gth and roth days, 278. From the i ith to the i6th days, 278, 279. 

 From the i6th day onwards, 279, 280. Changes in the general form 

 of the embryo during the 6th and 7th days, 280 282. During the 

 8th loth days, 282. From the i ith day onwards, 282. Feathers, 282. 

 Nails, 283. Ossification, 283. Changes in the venous system before 

 and after the commencement of pulmonary respiration, 283 289. 

 Changes in the arterial system, the modification of the aortic arches, 

 289 297. Summary of the chief phases of the circulation, 297303. 

 Hatching, 303. 



