CONTEXTS. 13 



PAGE 



the sympathetic system, 219— Evidence for continuous outgoing impulses from the 

 central nervous system, 220— Rigor mortis as affected by the nervous system. 220 

 Modification of reflexes by simultaneous and successive afferent impulses, -2,21— Effects 

 of afferent impulses on reflexes, 223— Inhibition of reflexes, 223. 



C. Reactions Involving the Encephalon 226 



The path of afferent impulses in the central nervous system, 226— Degenerations in 



the spinal cord after hemisection, 228— Physiological observations on afferenl pathways 

 in the central nervous system, 229— The nerves of common sensation. 230- I he nerves 

 of pain and their pathway in the cord, 231— The pathways ol impulses m the cord, 

 233— The nuclei and courses of the cranial nerves, 230— The pathway ot the libres ot 

 the optic nerve, 238— The pathway of the fibres of the olfactory nerve, 240. 



D. Localization of Cell-gboups in the Cerebral Cortex 241 



The discovery of localization of function in the cortex, 241— Effects of stimulation 



of the i cortex, 241 Course of the descending impulses, 244— Mapping ol the cortex, 

 247— The size of the cortical areas, 247— Subdivision of the cortical areas, 247- Sepa- 

 rateness of centres and areas, 248— Multiple control of muscles from the cortex, 250— 

 Cortical control is crossed, 251— Course of impulses leaving the cortex, 251— Size ot 

 the pyramidal tracts in different mammals, 252. 



E. Localization in the Cerebral Cortex of the Cell-groups Receiving the 



Afferent Impulses • ~° 2 



Sensory regions of the cortex, 252— Delimitation of the sensory areas, 253— Hemi- 

 anopsia 255— Association-fibres and association-centres (Flechsig), 256— Aphasia, 257 

 —Relative importance of the two hemispheres, 258— Composite character of incoming 

 impulses, 260— Variations in association, 260 — Latent areas, 261. 



F. Comparative Physiology of the Divisions of the Encephalon 262 



Methods of determining, 262— Removal of central hemispheres, 263— Functions of 



the corpus callosum, 270— Functions of the corpora striata, 271— Functions of the 

 thalamus, 271— Functions of the cerebellum, 272. 

 Part III.— Physiology of the Nervous System Taken as a Whole 274 



A. Weight of the Brain and Spinal Cord 2/4 



Weight of the encephalon and spinal cord, 274— Weight of the encephalon, 275 -In- 

 terpretations of weight, 277— Weights of different portions of the encephalon, 277— 

 Effect of social environment, 277— Brain-weight of criminals, 277— Brain-weights of 

 different races, 278— Weight of the spinal cord, 278. 



B. Growth Changes 2 <8 



Growth of the brain, 278— Relation between growth of body and that of encephalon, 



280— Increase in the number of functional nerve-elements, 280— Increase in the fibres 

 of the cortex, 282— Significance of medullation, 283— Increase in the mass of the neu- 

 rones, 283— Number of cells, 283— Change in specific gravity with age, 284. 



C. Organization and Nutrition of the Central Nervous System 285 



( >rganization in the central system, 285— Defective development of the central system, 



285— The central nervous system of laboratory animals, 286— The blood-supply of the 

 central system, 286— The influence of glands on the nervous system, 289 The influ- 

 ence of starvation on the nervous system, 289— Fatigue of the central nervous system, 

 289— Daily rhythms in the activity of the central nervous system, 289— The time 

 taken in central processes, 291. 



D. Sleep ■« 



Conditions favoring sleep, 291— Causes of sleep, 292— Condition of the central 



nervous system in sleep, 293 — Effect of loss of sleep, 295. 



E. Old Age of the Centbal System 295 



Metabolism in the nerve-cells in old age, 295- -Decrease in weight of the brain in old 



age, 296 Changes in the encephalon in old age, 296— Changes in the cerebellum in 

 old age, 296, 



THE SPECIAL SENSES - !,s 



A. Vision (By Hknky P. BOWDITCH) 298 



The general physiology of vision. 298— The mechanical movements <>f the eyeballs 

 around various axes, 298- The muscles of the eye. 299 The dioptric apparatus of the 

 eye, 300 The refracting media of the eve. 302 The optical constants of the rye, 304 

 —The mechanism of accommodation, 306 The range of accommodation, 312 Myopia 

 and hypermetropia, 313— Presbyopia, 314— Spherical aberration, 315 Chromatic 

 aberration, 316 Astigmatism, :;i7 [ntraocular images, 320— Muscse volitantes, 320 

 —The retinal vessels, 32] circulation of blood in the retina, 322 The innervation 

 and movements of the iris, 322 The principle of the ophthalmoscope, 326 The 

 structure of the retina, 327 -The blind-spot of the retina. 328 Changes produced m 

 the retina bv light, 330— The production of the sensation of light, 331 The qualita- 

 tive modifications of light, 332 Color-sensations, 333 Means of producing color- 



