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LEFT HYPEB-ffiMIA 101 HYPNOTISM assembled in a riotous manner against Orestes, who was obliged to fly from the city. They then seized Hypatia, and having torn her in pieces, burnt her mangled limbs to ashes, 415 A. D. HYPEREMIA (hi-per-e'-me-a), a plethora or fullness of blood. The whole mass of the blood is increased to a vari- able extent. The face is full and turgid, with a purplish tinge. There is a ten- dency to lassitude and sleep. Called also polysemia. HYPEB-ffiSTHESIA (hi-per-es-the'- ze-a), an excessive excitability of the parts of the nervous apparatus which have to do with sensation, special or common. Abnormal sensibility to pain is, however, more correctly called "hy- peralgesia." In this condition, as in tic- douloureux, the slightest stimulus may cause a paroxysm of pain, even a current of air or a noise bringing on an attack; while in hyperaesthesia of the special senses bright flashes of light may be seen, sounds may be heard, and even smells and tastes experienced in the ab- sence of any objective cause. HYPERBOLA (hi-per'bo-la), in mathematics, one of the three conic sec- tions. It is a plane curve of such a form that if from any point in it two straight lines be drawn to two given fixed points, the excess of the straight line drawn to one of the points above the other will al- ways be equal. The two points are called the foci. Other terms used of the hyper- bola are abscissae, parameter, latus rec- tum, directrix, and a term peculiar to it, asymptotes. HYPERICACE^, or HYPERI- CINiE (hi-per-e-kas'-e-'i), a natural order of about 300 known species, trees, shrubs, and herbaceous plants, widely distributed over the world, and in very different climates, but particularly numerous in North America. The species of Vismia yield a substance re- sembling gamboge. Many of the hyper- icaoex belong to the genus Hypericum, or St. John's Wort. HYPERION, in astronomy, the name given to the 7th satellite of Saturn, dis- covered in 1848, at the Harvard Observa- tory by G. P. Bond. It is just outside the satellite Titan, and the considerable mass of the latter causes perturbations in the orbit of Hyperion, which have proved to be a difficult problem in celes- tial mechanics, and a unique case in the solar system. HYPERMETROPIA (hi-per-met-ro- pe-a), far-sightedness; it is. the opposite of myopia, or near-sightedness, and dif- fers from presbyopia in being congen- ital. HYPERSTHENITE, a more or less coarsely crystalline igneous neck allied to gabbro. It is an aggregate of labra- dorite (felspar) and hypersthene, and is of plutonic origin. HYPNOTISM, that which formerly was, that which, popularly, still is called "mesmerism," or, more exactly "animal magnetism," founded on a belief in a so-called "magnetic fluid" which is sup- posed to pass from operator to subject, has become recognized as hypnotism. The actual foundation of modern hyp- notic suggestion was discovered by Lie- beault of Nancy. After several years of practical experience in 1866, he v/rote his first book on the subject. It was shelved and he was pronounced erratic. Hypnotism remained a curiosity and Liebeault's book was not reproduced till six years after Charcot, in 1878, began his studies in Hypnotism. In 1884 Bernheim wrote his charming book on suggestion and this created a demand for Liebeault's book, which then gave him his lasting reputation. He was Bern- heim's teacher. The word hypnotism means putting a person to sleep and means nothing else. If an individual seems to be subjected to another in the waking state it should be said that he is unduly influenced. He is not hypno- tized. That would mean that he was asleep. The means by which hypnotism is used is "suggestion." A person may be influ- enced by suggestion in the waking state, for suggestion is a great force in daily life. As connected with hypnotism, how- ever, suggestion is the expression of an idea or combination of ideas which be- comes impressed upon the mind of the somnolent subject to whom it is ad- iressed. Conscious or unconscious re- sults are sure to follow. If a subject be awake he can, accord- ing to the strength of his will and de- sire, control to a greater or lesser degree the effect of a suggestion which he has received. In the hypnotic state this self-control is decreased in a degree corresponding to that of the increase of the degree of sleep. Nevertheless, if merely the first degree of hypnosis have been attained, the subject, conscious of all he hears, may be influenced by the suggestion of the op- erator. In this way a vast amount of relief has been given to individuals who may claim that they have not been af- fected at all. In the hypnotic state there are nine sharply marked degrees of somnolence. In the first six degrees not-