444 



THE BODY AT WORK 



Hearing, Helmholtz's theory of analysis 

 of sounds, 419 



range of sensations, 418 



sense of, 404 



upper limit, 418 

 Heart, anatomy, 217 



automatism of, 238 



development, 218 



murmurs, 229 



muscular tissue, minute structure, 

 261 



nerves regulating beat, 237, 239 



sounds of, 228 



valves, their mechanism, 226 



work done by, 219, 223 

 Heat, production of, by muscles, 254, 256 

 Heat-spots in skin, 429 

 Helmholtz's theory of organ of Corti, 419 

 Hering's theory of colour- vision, 388 

 Hormones, meaning of term, 89, 124 



of pancreas and liver, 127 



of stomach, 123 



Humours in ancient medical theory, 79 

 Hunter, experiment of grafting cock's 



spur in its comb, 47 

 Hydrochloric acid, part taken in diges- 

 tion, 114 



Hydrophobia, protective inoculation, 78 

 Hyperpncea, excessive respiratory 



efforts, 182 

 Hypoblast, a layer of the embryo, 97 



Illusions of movement, 335, 384 



of size and distance, 400 

 Immunity, acquisition of, 20 

 Impulse of the heart, 225 



rate of passage in muscle, 280 

 in nerve, 278, 280 



theory of nerve conduction, 282 

 Inhibition, explanation of term, 311 



of reflex actions, 311 

 Insects, efficiency of their muscles, 261 

 Instinct, due to brain-pattern, 359 

 Intelligence of animals, 359 

 Internal secretions, 83 

 Intestinal juice, digestive action, 119 

 Intestine, large, sacculation of its walls, 

 101 



small, folds and glands of mucous 



membrane, 102 

 Intestines, movements of, 103 



nerves of, 105 



size and situation, 100 

 Iodine, importance of, to economy, 89 

 lodothyrin, goitre due to deficiency of , 90 

 Iris, its function in regulating admis- 

 sion of light to eye, 394 

 Iron in food, 67 



in haemoglobin, 67 



use of, in treatment of anaemia, 67 

 Irritability, a function of protoplasm, 10 



Japanese, cultivation of sense of smell 



by, 370 

 Judgment of angles, 402 



of distance and size, 401 



of meaning of sensations, 396, 399 



Kidney, ancestral history, 195 

 elimination of indigo by, 207 

 of birds and reptiles, 200, 207 

 hydrostatic mechanism, 189 

 minute anatomy, 196 

 Kinaesthetic sensations, absence from 



dreams, 363 

 part played by, in voluntary 



actions, 354 

 representation in cortex of 



brain, 350, 352 

 Knee-jerk, 274 



Labyrinth of ear, 413 



Lactate of ammonia, relation to urea, 



13 



Lac teals, lymphatic vessels of ali- 

 mentary canal, 43, 131 

 Lactic acid produced in muscle, 46, 146 

 Larynx, closure during swallowing, 433 



structure of, 430 

 Latent period of muscle after nervous 



impulse reaches it, 278 

 Laughter, respiratory mechanism of, 



180 

 Lecithin produced by metabolism of 



nerve-tissue, 118 

 Leech, ganglion cells of, 298 

 Leucocytes as protective agents, 52 

 death of, 54, 57 

 migration of, 49 

 number in lymph and in blood, 



49, 61 



origin of, 33, 51 

 source of fibrin-ferment, 74 

 Leucocythaemia, excess of leucocytes 



in the blood, 215 

 Levers to which muscles are attached, 



286 



Light, emission of, by animals, 291 

 Lime, influence upon coagulation of 



blood, 75 



curdling of milk, 75 

 Lithates, or urates, constituents of 



calculi, 213 



Liver, destruction of red blood-cor- 

 puscles in, 83 

 form and structure of, 160 

 former theories of its functions, 



129, 163 

 manufactures urea and uric acid, 



146, 162 



of well-fed sheep, 147 

 origin of, in vertebrate phylogeny, 



