CONTENTS. xiil 



CHAPTER VI. 



THE CHANGES WHICH TAKE PLACE DURING THE FOURTH DAY, pp. 141 173. 



j. Appearances on opening the egg. 2. Growth of the amnion. 

 3. Narrowing of the splanchnic stalk. 4. Increase in the cranial flexure. 



5. The first appearance of the limbs. 6. Growth of the head. 7. Changes 

 in the nasal pits. 8. Formation of the mouth. Q. The cranial nerves. 

 10. .The allantois. n. Changes in the protovertebras ; the spinal ganglia. 

 12. The secondary segmentation of the vertebral column. 13. Changes in 

 the notochord. 14. Ossification of the vertebrae. 15. The ribs. if>. 

 Changes in the muscle-plates. 17. The Wolffian body and duct. 18. The 

 duct of Mu'ller. 19. The kidneys. 20. The ovaries and testes. i\. 

 Changes in the arterial system. 22. Changes in the venous system; the 

 veins of the liver. 23. Changes in the heart; the ventricular septum. 

 24. Recapitulation. 



CHAPTER VII. 

 THE CHANGES WHICH TAKE PLACE ON THE FIFTH DAY, pp. 174 199. 



i. Appearances on opening the egg. i. The growth of the limbs. 

 3. The cranium; the investing mass and trabeculae. 4. Changes in the 

 face ; formation of the nose and nasal passages. 5. Appearance of the anus. 



6. Changes in the spinal cord ; the formation of the grey and white columns, 

 and of the posterior and anterior fissures. 7. Changes in the heart; the 

 rudiment of the auricular septum, the division of the bulbus arteriosus into 

 aorta and pulmonary artery, the formation of the semilunar valves. 8. Changes 

 in the heart during the sixth day. 9. Subsequent changes in the heart; the 

 completion of the auricular septum, the arrangement of the openings of the 

 venae cavte. 10. Histological differentiation; the fate of the three primary 

 layers, u. Recapitulation. 



CHAPTER VIII. 



FKOM THE SIXTH DAY TO THE END OF INCUBATION, pp. 200 224. 



r. The commencement of distinct avian differentiation. 2. The foetal 

 appendages during the sixth and seventh days. 3. During the eighth, ninth 

 and tenth days. 4. From the eleventh to the sixteenth day. 5. From the 

 sixteenth day onwards. 6. The changes in the general form of the embryo 

 during the sixth and seventh days. 7. During the eighth, ninth and tenth 

 days. 8. From the eleventh day onwards ; feathers, ossifications. 9. Changes 

 in the venous system before and after the commencement of pulmonary respi- 

 ration. 10. Changes in the arterial system, the modifications of the aortic 

 arches, u. Summary of the chief phases of the circulation. 12. Ex- 

 clusion from the egg. 



