Sleep, affected by certain winds, 45 artificial, mode of its production, 22 caused by the alternation of day and night, 17 caused by depressing emotions, 19 caused by exhaustion, 19 caused by fatigue, 19 caused by painful impressions, 19 caused by the venereal act, 19 definition of, 1 dreamless, 14 duration of, 4, 110 effects of its invasion upon the intellectual faculties, 13 effect of, upon consciousness, 13, 14 fatigue theory of, 20 favored by darkness, 18 favored by the suppression of sensation, 18 hindered by heat, 44 hindered by light, 39 hindered by smells, 42 hindered by sounds, 41 introductory stage of, 2 invasion of, 10, 117 measure of its depth by the experiments of Kohlschütter, 16 Obersteiner’s theory of, 20 Pflüger’s hypothesis regarding the cause of, 21 preceded by sleepiness, 2 Preyer’s theory of, 20 rapid induction of, in certain cases, 24 relation between the duration of, and the average length of the night, 17 stages of, 4 the cause of, 29 unequal incidence of, upon different portions of the brain, 13 Sleep-drunkenness, 180, 181 Sleepiness, precursive of sleep, 2 Sleeping dropsy, 30 Sleeplessness, causes of, 39 Smells, abolition of sleep by, 42 Smile, during sleep, 12 Smith, E., experiments of, on oxidation in the tissues, 9 Snoring, occasional interruption of sleep by, 11 Society for Psychical Research, investigations by, 149, 217 Sodium bromide, 88 Somniation, 169 Somnambulic dreams, 171, 178, 181 recollections of, 188 Somnambulic form of artificial somnambulism, 222 Somnambulic lethargy, 171, 173 contrasted with lucid lethargy, 176 Somnambulic life, 169, 204 a case of, 206 a case of, related by Azam, 208 a case of, related by Macnish, 206 Somnambulism, 166 artificial, 214 case of, related by Prof. J. Adams Allen, 185 case of, related by J. P. Frank, 195 case of, related by Macario, 192 case of, related by Mesnet, 196 case of, related by P. Max Simon, 182 causes of, 166 condition of sensory organs during, 191 dependence of, upon partial sleep of the brain, 11 likeness of, to hypnotism, 203 moral responsibility in, 203 phenomena of, 167, 210 physiological cause of, 180 relation of memory with events of, 192 varieties of, according to A. Maury, 168 varieties of, according to Ball and Chambard, 169 varieties of, diagrammatically exhibited, 172 violent impulses during, 193 Somnolence, 30 Somnolentia, 180, 181 Sound, effect of, to hinder sleep, 42 effect of, to induce sleep, 42 Spasmodic croup, 110 Special sense organs, affections of, 39 Special senses, condition of, during invasion of sleep, 11 perversion of, during the hypnotic state, 223 Spinal cord, irritability of, 110 reflex energy of, during sleep, 3