CHAPTER III 



THE LATER DEVELOPMENT OF THE FROG: 



ORGANOGENY 



PAGE 



INTRODUCTION 127 



I. THE NERVOUS SYSTEM 128 



1. The Central Nervous System 128 



2. The Peripheral Nervous System 135 



A. The Cranial Nerves 136 



B. The Spinal Nerves ... 142 



C. The Sympathetic System 143 



II. THE SPECIAL SENSE ORGANS 144 



1. The Eye 144 



2. The Ear 149 



3. The Olfactory Organ 153 



4. The Sense Organs of the Lateral Line 156 



III. THE ALIMENTARY TRACT AND ITS APPENDAGES . . 158 



1. The Derivatives of the Fore-gut 159 



2. The Derivatives of the Mid-gut ... 168 



3. The Derivatives of the Hind-gut 169 



IV. THE MESODERMAL SOMITES 170 



V. THE VASCULAR SYSTEM 174 



1. The Heart 174 



2. The Origin of the Blood and Vessels 178 



3. The Arterial System . . 179 



4. The Venous System 185 



5. The Lymphatic System and- the Spleen 189 



6. The Formation of the Septum Transversum 191 



VI. THE URINOGENITAL SYSTEM . . 192 



1. The Excretory System .192 



A. The Pronephros and the Pronephric Duct . 193 



B. The Mesonephros (Wolffian Body) . . . . 198 



2. The Reproductive System 201 



A. The Gonoducts .... . . 202 



B. The Gonads 203 



3. The Adrenal Bodies 206 



126 



