CONTENTS. 



SECTION a. 



PAGE 

 359 

 361 

 369 



PART III. A CRITICAL DISCUSSION OP MY OWN OBSERVATIONS AND THOSE 



OP OTHER WRITERS, ON THE SEXUAL AND ASEXUAL DEVELOPMENT OF 

 SALPA. 



PAOC 



CHAPTER IX. THE ORIGIN AND MATURATION OP 



THE EGG OP SALPA, 207 



SECTION 1. The Embryonic Germ Cells, . . . 307 



SECTIONS. Seeliger's account of the Germinal Mass, 211 



SECTIONS. The Differentiation of the Germinal Cells, 314 



SECTION 4. The Homology of the Germinal Mass, . 317 



SECTION 5. The Maturation of the Egg, . . . 331 

 SECTION 6. Summary of the History of the Ovarian 



Eggs of Salpa, 335 



SECTION 7. The Number of Eggs, .... 236 



CHAPTER X. SEX IN SALPA 229 



CHAPTER XI. THE FERTILIZATION AND SEGMEN- 

 TATION OF THE EGG 235 



SECTION 1. The Changes which accompany Fertili- 



270 



272 



zation, 

 SECTION 3. 

 SECTION 3. 

 SECTION 4. 



235 

 237 

 238 



Fertilization, 



Segmentation, 



The Segmentation of Salpa Hexagona 

 as compared with that of Clavelina, . . . 240 

 SECTION 5. The Significance of the Symmetry of the 



Salpa Embryo, 341 



CHAPTER XII. THE ACCESSORY PARTS OP THE 



EMBRYO, 244 



SECTION 1. The Composition of the Embryo, . . 344 



SECTION 3. The Foetal Membranes = Annexes extra- 



foetales, Barrels (6), p. 467, 244 



SECTION 3. The Supporting Ring, . . . .246 



SECTION 4. The Embryo Sac, 347 



SECTION 5. The Fate of the Fcetal Membranes, . 349 



SECTION 6. The Literature of the Foetal Membranes, 352 



CHAPTER XIII. THE FOLLICLE AND THE PLA- 

 CENTA, 258 



SECTION 1. The Origin of the Follicle, ... 358 



The Nutrition of the Eggs, 

 The Migration of the Follicle, 



SECTION 3. The Fate of the Follicle, 



SECTION 4. The Disintegration of the Embryonic 

 Portion of the Somatic Layer of the Follicle, 



SECTION 5. The Fate of the Follicular Lining of the 

 Atrium and Gill Tubes, 



SECTION 6. The Nutrition of the Blastomeres and 

 the Fate of that part of the Visceral Layer of the 

 Follicle which penetrates between the Blasto- 

 meres, 273 



SECTION 7. The Fate of the portion of the Visceral 



Layer which invests the Blastomeres, . .' . 277 



SECTION 8. The Placenta, 377 



SECTION 9. The " Test Cells " of Salpa, . . 383 



CHAPTER XIV. THE ONTOGENY OF THE ORGANS 



OP SALPA, 284 



SECTION 1. The Salpa Embryo, 284 



SECTION 2. The Aggregated Salpa;, .... 285 



SECTION 3. The Ectoderm of the Salpa Embryo, . 286 

 SECTION 4. The Ectoderm of the Stolon and that of 



the Aggregated Salpa, 287 



SECTIONS. The Nervous System of the Salpa Em- 

 bryo, 288 



SECTION 6. The Nerve-tube of the Stolon, . . 390 



SECTION 7. The Ganglia of the Aggregated Salpa;, . 391 

 SECTION 8. The Perithoracic Tubes and the Atrium, 



or Cloaca of the Salpa Embryo, .... 2*.:2 

 SECTION 9. The History of the Perithoracic Struc- 

 tures of the Aggregated Salpie, .... 295 

 SECTION 10. The Digestive Organs of the Embryo, 299 

 SECTION 11. The Endodermal Tube of the Stolon 



aud the Digestive Tract of the Aggregated Salpa, 399 



SECTION 13. The Heart and the Eleoblast, . . 303 

 SECTION 13. The Ovary and Testis, . . . .303 



PART IV. THE EYES AND SUBNEURAL GLAND OP SALPA. 

 By MAYNARD M. MKTUALP, Fellow of the John* Hopkins University. 



1'AOE 



INTRODUCTION, 307 



SECTION 1. The Eyes, 308 



Descriptive, 308 



The Anatomy of the Eye of Cyclosalpa Pinnata, 



Solitary Form, 30!l 



The Development of the Eye of Cyclosalpa Pinnata, 



Solitary Form, 311 



The Anatomy of the Eyes of Cyclosalpa Pinnata, 



Chain Form, . 313 



The Development of the Eyes of Cyclosalpa Piu- 



nata, Chain Form, 317 



The Anatomy of the Eyes in other Species of Sal- 



pidse, 320 



Theoretical 386 



SECTION 2. The Innervat ion of the Ciliated Funnel, 344 

 SECTION 3. The Anatomy and Development of the 

 Subneural Gland in Salpidie, with incidental re- 

 marks upon the Homology of the Nervons System 



in different Groups of Tunicates, . . . :!4l> 



APPENDIX I, 363 



APPENDIX 11, 364 



APPENDIX III, 367 



LIST OF PAPERS KEFEKKED TO IN PART IV, . . 371 



PART V. EXPLANATION OP THE PLATES. 



