TABLE OF CONTENTS. 



PAGE 



Locomotion among the Higher Animals . . . . 145 



II. Nervous System 145 



Its Regular Development 145 



Diffuse Nervous System 146 



Linear Nervous System 14'; 



Ganglionic Central Nervous System 146 



Subossophageal (or Brain) Ganglia 147 



Ladder Nervous System 147 



Tubular System 148 



Relations between the Nervous System and the Skin . 148 



III. Sensory Organs 148 



Sensations of the Lower Animals 148 



Anatomy Gives Insufficient Knowledge of Sensory 



Organs 149 



Tactile Organs 150 



Organs of Smell and of Taste 150 



Organs of Hearing and of Sight 151 



History of the Auditory Organs . 151 



Auditory Pit 152 



Other Forms of Auditory Organs 153 



Function of the Semicircular Canals 153 



The Eye 153 



The Rods and Cones 153 



The Optic Ganglion 154 



Refractive Bodies in the Eye 154 



The Eye of the Vertebrates 155 



The Various Types of Eyes 156 



Summary of the Most Important Points of Organology 156 

 iVo Promorphology, or Study of the Fundamental 



Forms of Animals 158 



Organic and Inorganic Bodies ........ 158 



Symmetry 159 



Bilateral Symmetry 162 



Antimeres and Metameres 163 



Internal and External Metamerism 164 



Homonomous and Heteronomous Metamerism . . 164 



Heteronomy and Homonomy 165 



II. General Embryology 165 



Origin of Organisms 165 



I. Generatio Spontanea: Archegony ....... . . . 166 



Theory of Spontaneous Generation 166 



First Origin of Life 167 



II. Generation by Parents, or Tocogony . 168 



Two Principal Methods . i6S 



a. Asexual Reproduction: Monogony 168 



Monogony Denned . . . 168 



