CONTENTS xiii 



CHAl'. PAGE 



ticity, 207. Strenoth of Materials, 208. Girders and 

 Trusses, 209. Mucoid Tissue, Fibrous Tissue, Elastic 

 Fibres, 210. Endothelium, Fat, 211. Pigment, 212. 

 Cartilage and Bone, 212-220. Relative Strength of 

 Bones, 213. Internal Structure, 214-218. Fractures, 

 218. Lubrication, 218. Joints, Tendon Sheaths, 210. 



XVIII. THE INTELLIGENCE SERVICE. NERVE CELLS . 221 



Neuron, 221. Structvn-e and Function, 222. Miiller's 

 Law, 223. " All or Nothing," 224. Nature of Impulse. 

 Electrical Changes, 225. Cause of Electrical Changes, 

 226. Refractory Period. Summation, 227. Fatiffue. 

 Metabolism, Temperature Coefficient. Polarisation. 228. 

 Negative Polarisation, Polarisation Model, 221). Elec- 

 trotonus, 230. Positive Polarisation, 231. Theory, 232. 



XIX. OUTPOSTS OF THE INTELLIGENCE SERVICE. 



(a) GENERAL AND INTRA-COMMUNAL RECEPTORS 233 

 Threshold. 233. Adaptation. Frequency of Discharge, 

 234. Stimulus and Sensation, Fechner's Law, 235. 

 ' Classification of Receptors, 236. I. Phasic Receptors : 

 (1) Touch, 237 ; (2) Tickle, 238 ; (3) Pain, 239. 

 II. Phasic-Postural Receptors : (4) Pressure, 240 ; 

 (5) Temperature. 241. III. Postural Receptors, 242. 

 IV. Special Receptors : (6) Taste, 242 ; (7) Smell, 244 ; 

 (8) Hunger, 246. 



XX. (b) DISTANCE RECEPTOR FOR SOUND. THE EAR . 249 



Tympanic Membrane, 250. Ossicles, 252. Mechanism 

 of Middle Ear, 254. Cochlea, 256. Resonance Theory, 

 258. Displacement Theory, 262. Pressure-Pattern 

 Theory, 263. Differentiation of Sounds in Intensity, 

 264; in Timbre, 265. Advantages of Form of Cochlea, 

 265. Binaural Hearing, 266. Bone Conduction, 266. 

 Utricle and Saccule, 267. 



XXI. (c) DISTANCE RECEPTOR FOR LIGHT. THE EYE . 272 



Physics of Refraction, Lenses, etc., 272-275. Anatomy 

 of the Eye, 276-278. The Eye as an Optical Instru- 

 ment, 278. Refractive Indices of Media, 278. San- 

 son's Images, 279. Accommodation. 280. Prevention 

 of Optical Defects. 282. Mechanism of Retina, 285. 

 Effects of Light on Retina, 287. Movements of the Eye- 

 ball, 290, Binocular Vision, 292. Analysis of Retinal 

 Stimuli, 295. Ophthalmoscopy, 296. 



SECTION IV : TRANSPORT 



XXII. INLAND TRANSPORT. THE BLOOD .... 298 



Development, 299. Function, 300. Composition. 300 

 -317. Plasma. 301. Clotting, 303-310. Crystalloids 

 of Plasma, 310. Blood Corpuscles, 312 321. Shape of 

 Erythrocytes, 313. Contents of Erythrocytes, 316. 



