CONTENTS. 



CHAPTER I. 



FAGB 



The Uses and Origin of a Nervous System . . # I 



CHAPTER 11. 



The Structure of a Nervous System — Nerve Fibres, 



Cells, and Ganglia 26 



CHAPTER III. 

 The Use and Nature of Sense Organs .... 55 



CHAPTER ly. 

 The Nervous System of Mollusks 70 



CHAPTER y. 

 The Nervous System op yERMEs 86 



CHAPTER yi. 

 The Nervous Syspem of Arthropods 93 



CHAPTER yil. 



Data concerning the Brain derived from the Study of 



THE Nervous System of Invertebrates . . . 107 



