TABLE OF CONTENTS. 211 



muscles. Division into dorso-lateral and ventro-lateral sections. Derivation of limb- 

 muscles from muscle-plates. Vertebral column and notochord. Previous investi- 

 gations. Formation of arches. Formation of cartilaginous sheath of notochord and 

 membrana elastica externa. Differentiation of neural arches. Differentiation of 

 hrcmal arches. Segmentation of cartilaginous sheath of notochord. Vertebral and 

 intervertebral regions. Notochord. 



CHAPTER VIII. 



DEVELOPMENT OF THE SPINAL NERVES AND OF THE SYMPATHETIC 

 NERVOUS SYSTEM, pp. 378 396. 



The spinal nerves. Formation of posterior roots. Later formation of anterior 

 roots. Development of commissure uniting posterior roots. Subsequent develop- 

 ment of posterior roots. Their change in position. Development of ganglion. 

 Further changes in anterior roots. Junction of anterior and posterior roots. Summary. 

 General considerations. Origin of nerves. Hypothesis explaining peripheral growth. 

 Hensen's views. Later investigations. Gotte. Calberla. Relations between 

 Annelidan and Vertebrate nervous systems. Spinal canal. Dr Dohrn's views. 

 Their difficulties. Hypothesis of dorsal coalescence of lateral nerve cords. Sympa- 

 thetic nervous system. Development of sympathetic ganglia on branches of spinal 

 nerves. Formation of sympathetic commissure. 



CHAPTER IX. 



DEVELOPMENT OF THE ORGANS IN THE HEAD, pp. 397 445. 



DEVELOPMENT OF THE BRAIN, pp. 397 407. General history. Fore-brain. 

 Optic vesicles. Infundibulum. Pineal gland. Olfactory lobes. Lateral ventricles. 

 Mid-brain. Hind-brain. Cerebellum. Medulla. Previous investigations. Huxley. 

 Miklucho-Maclay. Wilder. ORGANS OF SENSE, pp. 407 412. Olfactory organ. 

 Olfactory pit. Schneiderian folds. Eye. General development. Hyaloid mem- 

 brane. Lens capsule. Processus falciformis. Auditory organs. Auditory pit. 

 Semicircular canals. MOUTH INVOLUTION and PITUITARY BODY, pp. 412 414. 

 Outgrowth of pituitary involution. Separation of pituitary sack. Junction with 

 infundibulum. DEVELOPMENT OF CRANIAL NERVES, pp. 414 428. Early devel- 

 opment of 5th, 7th, 8th, Qth and roth cranial nerves. Distribution of the nerves in the 

 adult. The fifth nerve. Its division into ophthalmic and mandibular branches. 

 Later formation of superior maxillary branch. Seventh and auditory nerves. Separa- 

 tion of single rudiment into seventh and auditory. Forking of seventh nerve over 

 hyomandibular cleft. Formation of anterior branch to form ramus opthalmicus super- 

 ficialis of adult. General view of morphology of branches of seventh nerve. Glosso- 

 pharyngeal and vagus nerves. General distribution at stage L. Their connection 

 by a commissure. Junction of the commissure with commissure connecting posterior 

 roots of spinal nerves. Absence of anterior roots. Hypoglossal nerve. MESOBLAST 

 OF HEAD, pp. 429 432. Body-cavity and my otomes of head. Continuation of body- 

 cavity into head. Its division into segments. Development of muscles from their 

 walls. General mesoblast of head. NOTOCHORD IN HEAD, p. 433. HYPOBLAST 

 OF THE HEAD, pp. 433434. The formation of the gill-slits. Layer from which 

 gills are derived. SEGMENTATION OF THE HEAD, pp. 434 440. Indication of 

 segmentation afforded by (i) cranial nerves, (2) visceral clefts, (3) head-cavities. 

 Comparison of results obtained. 



