CONTENTS xiii 



PAGE 



Association. Volition. Inhibition. Habit formation. Language. 

 Consciousness. Emotions. Cerebral functions compared in man 

 and animals. Nourishment of the brain 142 



CHAPTER XII 



THE CEREBELLUM. THE MEDULLA AND MIDBRAIN. THE SYMPA- 

 THETIC SYSTEM 



The cerebellum. The medulla and midbrain. The sympathetic system. 



Relation of the sympathetic system to emotional states .... 161 



CHAPTER XIII 



THE RECEPTOR SYSTEM. INTERNAL AND CUTANEOUS SENSATIONS 



The receptor system. Differences between sensations. Psychophysical 

 law. Classification of receptors. Internal senses. Muscle sense. 

 Hunger and thirst. Fatigue. Cutaneous senses. Pain. Touch. 

 Temperature sense. Peripheral reference of sensations. Percep- 

 tions. Sensory illusions 169 



CHAPTER XIV 



THE EAR. HEARING AND EQUILIBRATION. TASTE AND SMELL 



The external ear. The middle ear. Auditory ossicles. Internal ear. 

 Bony labyrinth. Membranous labyrinth. Organ of Corti. Loud- 

 ness, pitch, and timbre of sounds. Sympathetic resonance. Func- 

 tions of tympanic membrane. Functions of auditory ossicles. 

 Function of the cochlea. Auditory perceptions. Nerve endings 

 in semicircular canals and vestibule. Equilibrium sense. Smell. 

 Taste 187 



CHAPTER XV 



THE EYE AS AN OPTICAL INSTRUMENT 



The essential structure of an eye. The appendages of the eye. The lach- 

 rymal apparatus. The muscles of the eye. Anatomy of the eyeball. 

 Optic nerves, chiasma, and tracts. The retina. Refracting media 

 of the eye. The ciliary muscle. Properties of light. Refraction of 

 light. Accommodation. Short sight and long sight. Optical de- 

 fects of the eye. Hygiene of the eyes 207 



CHAPTER XVI 



THE EYE AS A SENSORY APPARATUS 



The excitation of the visual apparatus. Intensity of visual sensations. 

 Function of the rods. Visual purple. Duration of luminous sensa- 



