CONTENTS. 7 



Muscles of the middle ear Mastoid cells Eustachian tube Muscles of 

 the Eustachian tube Mucous membrane of the middle ear and of the Eu- 

 stachian tube General arrangement of the bony labyrinth, . Page 146 



CHAPTER VIII. 



PHYSICS OF SOUND. 



Laws of sonorous vibrations Reflection and refraction of sound Noise and 

 musical sounds Intensity, pitch, and quality of musical sounds Mechan- 

 ism of the siren Musical scale Harmonics, or overtones Resonators of 

 Helmholtz Resultant tones Summation toaes Harmony Discord 

 Beats a cause of discord Tones by influence (consonance), . . 166 



CHAPTER IX. 



USES OF DIFFERENT PARTS OF THE AUDITORY APPARATUS. 



Uses of the external ear -Structure of the membrana tympani Uses of the 

 membrana tympani Variations in tension Vibrations of the membrane 

 by influence Destruction of the membrana tympani Appreciation of the 

 pitch of tones Mechanism of the ossicles of the ear Articulations and at- 

 tachments of the ossicles Physiological anatomy of the internal ear Gen- 

 eral arrangement of the membranous labyrinth Vestibule Semicircular 

 canals Cochlea Liquids of the labyrinth Distribution of nerves in the 

 cochlea Organ of Corti Functions of different parts of the internal ear 

 Functions of the semicircular canals Functions of the parts contained in 

 the cochlea Summary of the mechanism of audition, . . . 196 



CHAPTER X. 



GUSTATION". 



Savory substances Relations between gustation and olfaction ; taste and flavor 

 Modifications of the sense of taste Nerves of taste Chorda tympani 

 Facial paralysis with impairment of taste Paralysis of general sensibility 

 of the tongue without impairment of taste Glosso-pharyngeal nerve (first 

 division of the eighth) Physiological anatomy General properties of the 

 glosso-pharyngeal Relations of the glosso-pharyngeal nerves to gustation 

 Differences in the properties of different portions of the gustatory organ 

 Mechanism of gustation Physiological anatomy of the organ of taste 

 Papillae of the tongue Taste-buds, or taste-beakers Connections of the 

 nerves with the organs of taste, . 232 



