Xll CONTENTS 



The External Genital Organs 423 



The Development of the Suprarenal Glands 426 



The Cortical Substance 427 



The Medullary Substance 427 



Anomalies 429 



References for Further Study 435 



CHAPTER XVI 



THE DEVELOPMENT OF THE INTEGUMENTARY SYSTEM 437 



The Skin 437 



The Nails 439 



The Hair ,, 440 



The Glands of the Skin 442 



The Mammary Glands 442 



Anomalies 444 



References for Further Study 446 



CHAPTER XVII 



THE NERVOUS SYSTEM 447 



General Considerations 447 



General Plan of the Vertebrate Nervous System 450 



Spinal Cord and Nerves 457 



The Epichordal Segmental Brain and Nerves 459 



The Cerebellum 466 



The Mid-Brain Roof 467 



The Prosencephalon 467 



General Development of the Human Nervous System During the First 



Month 472 



Histogenesis of the Nervous System 478 



Epithelial Stage Cell Proliferation 479 



Early Differentiation of the Nerve Elements 483 



Differentiation of the Peripheral Neurones of the Cord andj Epi- 

 chordal Segmental Brain 486 



Efferent Peripheral Neurones 486 



Afferent Peripheral and Sympathetic Neurones 489 



Development of the Lower (Intersegmental) Intermediate Neurones. 502 



Further Differentiation of the Neural Tube . . . . . . . 506 



The Spinal Cord 506 



The Epichordal Segmental Brain ..512 



The Cerebellum 525 



Corpora Quadrigemina 530 



The Diencephalon 53! 



