Therid. was introduced and proved by Hering in 1832. The spider is found in the West Indies, chiefly in the island of Curaçoa. It is about the size of a cherry-stone, is found on orange-trees, velvety black when young, with antero-posterior lines composed of white dots; on posterior of body there are three orange-red spots, and on the belly a large square yellow spot. It is very poisonous. It produces a highly sensitive, nervous condition with weakness, trembling, coldness, anxiety, faintness, and easily excited cold sweat. There are two well-marked keynotes, one or other of which will be found in most cases calling for Therid. (1) Extreme sensitiveness to noise; < by least noise; "sounds penetrate the teeth." The sensitiveness extends to vibrations of any kind, jar of a step, riding in a carriage or in a boat. The symptom also shows the relation Therid. has to bony structures as well as to the nervous organs they enclose: it meets cases of spinal irritation; and also cases of disease of the spinal and other bones. Caries, necrosis, and scrofulous disease of bones have all been cured with it. "In scrofulosis when the best remedies fail to relieve" (H. C. Allen). (2) "< Closing eyes." This applies to vertigo, and symptoms of the head and stomach. This forms the indication in many cases of seasickness, or sickness of pregnancy. The headaches are severe and affect the eyes, especially the left. The ears are highly sensitive. There are hallucinations of sight and hearing, luminous vibrations, and rushing sounds. Although there is "< closing eyes," there is also intolerance of light. A species of intoxication is induced, hilarity, talkativeness. "Time passes too slowly" is a well-marked symptom. Therid. has a peculiar cough: frequent, convulsive, head spasmodically jerked forward, knees jerked up to abdomen. Chackravanti (H. W., xxxvi. 345) relates a case of headache cured with Therid.: Mr. B., 35, well built, of bilious temperament, had for three months severe headache with nausea and vomiting, like sea-sickness, and shaking chills. Dulness and fulness in the head with throbbing beginning in occiput, preceded by flickering before the eyes. Head feels large and heavy. The pains begin in the morning, increase during the day, and last till evening. Excessive irritation, with loss of sustaining power. < From least overwork and motion; > by keeping quiet in horizontal position. Constipation, stools hard, small, dry. Therid. 3x was given, one drop in water twice daily. The pain was much better next day, and was gone in less than a week. Baruch (H. P., viii. 331) says of Therid. "In cases of scrofulosis, where the best chosen medicines do nothing, I always interpolate a dose of Therid., which must act for eight days, and I have seen the most surprising results from it, particularly in caries and necrosis. For phthisis florida Therid. is indispensable, and effects a certain cure if given in the beginning of the disease. In cases of rachitis, caries, and necrosis I depend chiefly on Therid., which, although it does not seem to affect the external scrofulous symptoms, apparently goes to the root of the evil and effectually destroys the cause of the disease." Peculiar Sensations are: As if her head was another strange head. As if vertex did not belong to her. Like a pressing pain in root of nose and about ears. As of a veil before eyes. As if too much air passed into nose and mouth. Mouth as if furred, benumbed. As if some one tapped her on groin when raising leg. As if a lump were lying in perinaeal region. Like labour pains in lower abdomen. As if a child were bounding in body. As if something in oesophagus were slipping towards epigastrium. As if bones were broken and would fall asunder. As if dying. Burning pains and itching are common; and a stitch high up in apex of left chest has proved a guiding symptom for Therid. in the cure of cases of phthisis. "Burning in liver region" has led to the cure of abscess and even cancer of that organ. The symptoms are < by touch; pressure; on ship-board; riding in carriage; closing eyes; jar; least noise. Lying = pain deep in brain; > flickering before eyes. < Stooping; rising; motion; exertion, going up or down stairs; walking. After washing clothes, nausea and fainting. < Every night. Warm water > nausea and retching. Warmth >. Cold <; cold water feels too cold. < By coitus (groin pains). < After stool (headache). Left side most affected.