CONTENTS. Vll 



Page 



Chapter V'. — Hearing 370 



§ 1. Acoustic Principles 370 



2. Physiology of Hearing in Man 376 



3, Comparative Physiology of Hearing 389 



Chapter VI.— Vision 398 



§ 1 . Object of the Sense of Vision 398 



2. Modes of accomplishing the object of Vision .... 402 



3. Structure of the Eye 411 



4. Physiology of Perfect Vision 419 



5. Comparative Physiology of Vision 42() 



Chapter VH. — Perception 453 



Chapter V'lli. — Comparative PHYSioLociy up the Nervous 



System 477 



§ 1 . General view vi' the functions of the Nervous 



System 477 



2. Nervous System of Invertebrate Animals 483 



3. Nervous System of Vertebrated Animals 495 



4. Functions of the Brain 504 



5. Comparative Physiology of Perception 508 



PART IV.— THE REPRODUCTIVE FUNCTIONS. 



Chapter I. — Reproduction .52 1 



Chapter II. — Organic Developement 5;j7 



Chapter III. — Decline of the System 555 



Chapter VI. — Unity oi Design 560 



• ^ 1"^-^ .' 575 



