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CONTENTS. XV 



CHAPTEE XV. PAGE 



THE ORGANS OF THE MIDDLE GERM-LAYER .... 341 



I. THE DEVELOPMENT OF THE VOLUNTARY MUSCULATURE . . 342 



A. The Primitive Segments of the Trunk ..... 342 



B. ,, Head-Segments ......... 351 



II. THE DEVELOPMENT OF THE URINARY AND SEXUAL ORGANS . 353 



() The Pronephros and the Mesonephric Duct .... 353 



(&) Mesonephros (Wolffian Body) ...... 359 



(c) Metanephros (Kidney) ....... 367 



(d) Miillerian Duct ......... 369 



(e) Germinal Epithelium ........ 374 



(/) Ovary ..'... ... .374 



(/) ,, Testis ...... . .382 



(//) ., Metamorphosis of the Different Fundaments of the Uro- 



genital System into their Adult Condition .... 385 



A. In the Male (Descemus testiculonnn} .... 387 



B. ., Female ( .. ovarioriim') .... 391 

 (0 The Development of the External Sexual Parts . .397 



III. THE DEVELOPMENT OF THE SUPRARENAL BODIES . . . 403 

 SUMMARY ............ 405 



CHAPTER XVI. 

 THE ORGANS OF THE OUTER GERM-LAYER ..... 416 



I. THE DEVELOPMENT OF THE NERVOUS SYSTEM .... 416 



A. The Development of the Central Nervous System . . . 416 

 (a) The Development of the Spinal Cord .... 418 

 (J) ,. ,, Brain ...... 421 



(1) Metamorphosis of the fifth Brain- Vesicle . . . 427 



(2) fourth 429 



(3) third 430 

 ^4) ., second 431 



Development of the Pineal Gland (Epiphysis cerebri) 432 



., Hypophysis (Pituitary Body) . 436 



(5) Fore-Brain Vesicle . . . 439 



. The Development of the Peripheral Nervous System . . 449 



(a) Spinal Ganglia ..... 449 



(&) Peripheral Nerves .... 452 



(e) Sympathetic System .... 462 



SUMMARY ............ 463 



II. THE DEVELOPMENT OF THE SENSORY ORGANS .... 467 



A. The Development of the Eye ....... 467 



(a) The Development of the Lens ...... 471 



(J) ., ,, Vitreous Body .... 474 



(c) Secondary Optic Cup and the 



Coats of the Eye . . .476 

 Optic Nerve . . . .484 



Accessory Apparatus of the Eye 486 



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