CONTENTS. Vll 



Page 



Chapter IV. — Smell 396 



Chapter V. — Hearing 414 



§ 1. Acoustic Principles 414 



2. Physiology of Hearing in Man 420 



3. Comparative Physiology of Hearing 434 



Chapter VI. — Vision 444 



§ 1. Object of the Sense of Vision 444 



2. Modes of accomplishing the objects of Vision 449 



3. Structure of the Eye 460 



4. Physiology of Perfect Vision 469 



5. Comparative Physiology of Vision 477 



Chapter VII. — Perception 508 



Chapter VIII. — Comparative Physiology of the 

 Nervous System 537 



§ 1. Nervous System of Invertebrated Animals. . . . 537 



2. Nervous System of Vertebrated Animals .... 553 



3. Functions of the Brain 561 



4. Comparative Physiology of Perception 566 



PART IV.— THE REPRODUCTIVE FUNCTIONS. 



Chapter I. — Reproduction 581 



Chapter II. — Organic Developement 599 



Chapter III. — Decline of the System 619 



Chapter IV. — Unity of Design 625 



Index 643 



