About 150 B.C. a sect called the Essenes was established for the study of curative and poisonous substances. The members were not all physicians, by any means, for one of the chief was King Mithridates, who invented the remedy known as mithridaticum. This celebrated nostrum of antiquity is said to have been a confection of twenty leaves of rue, a few grains of salt, two walnuts, and two figs, intended to be taken every morning and followed by a draught of wine. Two famous physicians and anatomists, _Herophilus_ (335-280 B.C.) and _Erasistratus_ (280 B.C.) took part in the medical teaching at Alexandria in the early days of that seat of learning. It is recorded that they did not confine their investigations to the dissection of the dead, but also vivisected criminals. _Cleombrotus_, another physician at this school, was sent for to attend King Antiochus, and was rewarded with a hundred talents, equal to about £15,000 sterling. There were several physicians of the name of _Chrysippos_ connected with the Alexandrian School. One was physician to Ptolemy Soter, the King of Egypt, and tutor to Erasistratus. This Chrysippos introduced the practice of emptying a limb of blood before amputation, according to the recent method of Esmarch, and is said to have employed vapour baths in the treatment of dropsy. In Alexandria, anatomy was properly studied.[8] _Herophilus_ made many anatomical discoveries, and some of the names he gave to parts of the body are now in use, for instance, torcular Herophili, calamus scriptorius, and duodenum. He described the connection between the nerves and the brain, and the various parts of the brain, and recognized the essential difference between motor and sensory nerves, although he thought the former arose in the membranes and the latter in the substance of the brain. He believed that the fourth ventricle was the seat of the soul. He attributed to the heart the pulsations of the arteries, but thought that the pulmonary veins conveyed air from the lungs to the left side of the heart, and he observed the lacteals without determining their function. Herophilus operated upon the liver and spleen, and looked upon the latter as of little consequence in the animal economy. He had a good knowledge of obstetric operations. His ideas in relation to pathology did not proceed much further than the belief that disease was due to corruption of the humors. He was more scientific and accurate when he taught that paralysis results from a defect in the nerves.