viii PHYSIOLOGY 



and quality of the excited tastes. 6. Inadequate stimuli ; the so-called 

 electrical taste. 7. Pathological alterations of taste-sense by disease or 

 poisons. 8. Specific energies of the nerves of taste. Bibliography. 



CHAPTER IV 



THE SENSE OF SMELL ...... 



1. Peripheral organs and nerves of smell. 2. External mechanism 

 of olfactory function. 3. Excitation of smell by odorous substances in 

 the form of gas or of aqueous solutions. Electrical excitation of smell. 

 4. Chemical and physical properties of odorous substances. 5. Classi- 

 fication of odours. 6. Determination of olfactory acuity (olfactometry 

 and odorimetry). 7. Specific energy of the olfactory apparatus deduced 

 from the phenomena of partial anosmia and partial olfactory fatigue. 

 8. Corrections and compensations of odours. 9. Physiological and 

 psychical value of olfactory sensations. Bibliography. 



CHAPTER V 



THE SENSE OF HEARING . . . .191 



1. The organ of hearing. 2. Functions of the external ear. 3. 

 Functions of the tympanic apparatus (tympanic membrane and chain of 

 ossicles). 4. Functions of internal ear muscles (tensor tympani and 

 stapedius). 5. Functions of tympanic cavity, Eustachian tube and 

 fenestra rotunda (cochleae). 6. Structure of organ of Corti, and dis- 

 similar vibratory properties of the rods, basilar membrane, and tectorial 

 membrane. 7. Compound tones, noises, simple tones, and differences 

 of pitch and strength. 8. Limits of the perceptive capacity for tones, 

 and faculty of discriminating between different tones. 9. Timbre 

 or quality of simple and compound tones. 10. Acoustic phenomena 

 perceived on the simultaneous production of several tones. 11. Theory 

 of perception of simple and compound tones. 12. Consonance and dis- 

 sonance of tones ; musical chords. 13. Rising and falling phases of 

 auditory sensation ; auditory fatigue. Entotic and subjective auditory 

 sensations and hallucinations. 14. Binaural audition and localisation 

 of sounds. Bibliography. 



CHAPTER VI 



DIOPTRIC MECHANISM OF THE EYE .... 266 



1. General anatomy of eyeball. 2. Formation of retinal images ; 

 underlying optical principles. 3. Optic constants of the eye. 4. 

 Static refraction of the eye (emmetropia and ametropia). 5. Refraction 

 of the eye ; mechanism and innervation of accommodation. 6. Far 

 point and near point of clear vision ; range and speed of accommoda- 

 tion. 7. Normal imperfections in the dioptric apparatus of the eye. 



