CONTENTS. 



PART I. A GENERAL ACCOUNT OP THE LIFE HISTORY OP SALPA. 



CHAPTER I. INTRODUCTORY, 



PACK 



1 



CHAPTER II. THE DEVELOPMENT OF THE SOLI- 

 TARY SALPA FROM THE EGG, .... 



SECTION 1. An Outline of the History of the Egg, . 



SECTION 2. The Foetal Membranes, .... 



SECTION 3. The Migration of the Follicle, 



SECTION 4. The Organs of the Embryo outlined in 



Follicle Cells, . 



SECTION 5. TheBlastodermicTissuesoftheEmbryo, 



SECTION 6. The Degeneration of the Follicle, . 



SECTION 7. The Placenta, 



SECTION 8. The Nutrition of the Embryo, 



CHAPTER III. THE MORPHOLOGICAL SIGNIFI- 

 CANCE OF THE SALPA EMBRYO, 

 The Embryology of Primitive Tunicates, . 

 Has the Egg of Salpa passed through a Stage with 



a large Food Yolk '! 



The Primitive Salpa Embryo, 



The Origin and Significance of the Follicle of Salpa, 



CHAPTER IV. THE ORIGIN OF THE PROLIFEROUS 



STOLON, 



SECTION 1. Outline Sketch, 



SECTIONS. The Orientation of the Stolon, 

 SECTION 3. The Ectoderm of the Stolon, 



17 

 17 

 21 

 24. 



28 

 32 

 42 

 46 



48 



54 

 55 



56 

 58 

 59 



00 

 6C 

 68 

 68 



SECTION 

 SECTION 

 SECTION 

 SECTION 

 SECTION 

 SECTION 



The Nerve Tube, 70 



The Endodermal Tube, .... 71 



The Blood Tubes, 73 



The Perlthoracic Tubes, . . . 75 



The Mesoderm of the Stolon, . . 7ti 



The Genital Rod, 76 



SECTION 10. The Derivatives from the Parts of the 



Stolon, 76 



CHAPTER V. THE TRANSFORMATION OF THE 

 STOLON INTO THE SERIES OF AGGREGATED 



SALP.E, 78 



SECTION 1. Outline Sketch, 78 



The Proliferous Stolon, 78 



The Segmentation of the Stolon, .... 78 



The Rudimentary Chain Salpa, .... 73 



The Secondary Changes, 79 



The Development of the Chain Salpa, ... 80 



SECTION 2. The General Characteristics of Aggre- 

 gated Salpa. 1 , S4 



SECTION 3. The Segmentation of the Stolon, . . s<i 



SECTION 4. The Development of the Chain Salpa, . '.c. 



SECTION 5. The Secondary Changes in the Position 



of the Aggregated Salpse upon the Stolon, . . 103 



SECTION 6. The Rotation of the Salpu-, . . .107 



SECTION 7. The Development of the Aggregated 



Form of Salpa Pinnata 11:! 



PART II. THE SYSTEMATIC AFFINITY OF SALPA IN ITS RELATION TO THE 

 CONDITIONS OP PRIMITIVE PELAGIC LIFE; THE PHYLOGENY OF THE 

 TUNICATA; AND THE ANCESTRY OP THE CHORDATA. 



PAQl 



CHAPTER VI. THE SYSTEMATIC POSITION OF 



SALPA, 123 



SKCTION 1. The Evidence that Salpa is descended 



from a Fixed Form, 128 



SECTION 2. Views on the Relationships of the Swim- 

 ming Tunicates, 120 



SECTION 3. Salpa and Doliolum, . . . .128 

 SECTION 4. Salpa and Pyrosoma, . . . .129 

 SECTION 5. The Nature of the Relationship of Salpa, 



Doliolum, and Pyrosoma to the Ascidians, . . 1JJ5 



CHAPTER VII. SALPA IN ITS RELATION- TO THE 



EVOLUTION OF LIFE, 140 



Contrast between Terrestrial Life and Marine Life, . UO 



I'AflE 



The Fauna of Mid-ocean, 145 



The Primary Food-supply, 147 



The Origin of Pelagic Animals, .... 149 



The Primitive Pelagic Fauna, 157 



The Origin of the Crustacea, 159 



The Phytogeny of the Metazoa, 163 



The Discovery of' the Bottom and its Effect on Evo- 

 lution, 168 



CHAPTER VIII. THE ORIGIN OF THE CHORDATA, 

 CONSIDERED IN ITS RELATION TO PELAGIC 



INFLUENCES, 178 



SUCTION 1. The Ancestral Chordata, . . . 178 

 SECTION 2. The Origin of the Tunicates, . . .182 



SECTION 8. The Anuelidau Hypothesis, ... 188 



