CONTENTS Xvii 



IV 



THE CENTRAL NERVOUS SYSTEM 



Page 

 SIMPLE REFLEX ACTIONS 370 



The spinal cord a seat of simple reflexes Influence of 

 afferent impulses on reflex action Threshold value 

 lower in end organ than in nerve-trunk Summation 

 of afferent impulses Segmental arrangement of reflex 

 apparatus Reflexes in man. 



TENDON REFLEXES 375 



Knee jerk Ankle jerk Gower's experiment. 



EFFECT OF STRYCHNINE ON REFLEX ACTION .... 377 



COMPLEX CO-ORDINATED REFLEXES 377 



Removal of cerebral hemispheres Posture, etc. Bal- 

 ancing experiment Retinal reflex Croak reflex. 



APPARENT PURPOSE IN REFLEX ACTION 381 



REFLEX AND REACTION TIME 382 



Reflex time Reaction time Reaction time with choice. 



INHIBITION OF REFLEXES 384 



Through peripheral afferent nerves Through central 

 afferent paths ; the optic lobes. 



THE ROOTS OF SPINAL NERVES 386 



Ludwig's demonstration Localization of movements at 

 different levels of the spinal cord. 



DISTRIBUTION OF SENSORY SPINAL. NERVES .... 388 



MUSCULAR TONUS 389 



Brondgeest's experiment. 



V 



THE SKIN 



SENSATIONS OF TEMPERATURE 390 



Hot and cold spots Outline Mechanical stimulation 

 Chemical stimulation Electrical stimulation Tem- 

 perature after-sensation Balance between loss and gain 



