CONTENTS. xv 



Color blindness. Fatigue of the retina and after-images. Con 

 trasts. Hering's theory of vision. Visual perceptions. Single 

 vision with two eyes - . 506 



CHAPTER XXXIII. 



THE EAR AND HEARING. 



The external ear. The tympanum. The auditory ossicles. The 

 internal ear. The organ of Corti. The loudness, pitch, and 

 timbre of sounds. Sympathetic resonance. Functions of the 

 tympanic membrane, of the auditory ossicles, of the cochlea, 

 and of the vestibule. Auditory perceptions 535 



CHAPTER XXXIV. 



TOUCH, THE TEMPERATURE SENSE, THE MUSCULAR SENSE, 

 COMMON SENSATION, SMELL, AND TASTE. 



Nerve-endings in the skin. The pressure sense. The localizing 

 power of the skin. The temperature sense. Modality of skin 

 sensations. The muscular sense. Pain. Hunger and thirst. 

 Smell. Taste.. 556 



CHAPTER XXXV. 



THE FUNCTIONS OF THE BRAIN AND SPINAL CORD. 



The special physiology of nerve-centres. The % spinal cord as a 

 centre. Reflex actions. The least-resistance hypothesis. The 

 education of the spinal cord. The inhibition of reflexes. Psy- 

 chical activities of the cord. The cord as a conductor of 

 nervous impulses. Functions of the brain in general. Func- 

 tions of medulla oblongata. Functions of cerebellum, pons 

 Varolii, and mid-brain. Sensations of equilibrium and func- 

 tions of semicircular canals. Functions of the fore-brain. 

 Hygiene of the brain * 573 



CHAPTER XXXVI. 



VOICE AND SPEE.CH. 



Anatom^ of larynx. The vocal cords. Causes of the varying 

 pitch of the voice. Range of the human voice. The' produc- 

 tion of vowels. Consonants.. 595 



