Philinus of Cos (286 B. C.) was looked upon as the founder of the school of the Empirics, and among its most distinguished disciples were: Serapion of Alexandria (279 B. C.), Glaucias, Apollonius Biblas, and--perhaps the most celebrated of them all--Herakleides of Tarentum (242 B. C.), who did such excellent work in the department of pharmacology. It was he, for example, who defined more precisely than had been done by any one of his predecessors the proper manner of employing opium. In addition, he wrote a commentary on the Hippocratic works and also separate treatises on medical, surgical and pharmaceutical topics. In the latter category belongs his book entitled “A Military Pharmacopoeia.” Last of all, Apollonius Mus, a distinguished follower of Herophilus, deserves to be mentioned because it was he who perfected the preparation of castor oil. At a still later date (158 B. C.) Zopyrus proved himself to be a most worthy successor to Herakleides. It was he who first classified drugs according to the effects which they produce, and he also invented or discovered the preparation named “ambrosia,” a general antidote for poisons of all kinds. Kings and princes were, at that period, in constant fear of being poisoned, and so it came about that those who were skilled in the knowledge and preparation of drugs were greatly stimulated by their royal patrons to find efficient antidotes. It is narrated that Attalus Philometer, King of Pergamum, the native city of the famous physician Galen, and Mithridates Eupator, King of Pontus, cultivated poisonous plants in their gardens and tried the effects of the poisons distilled from them on criminals. They also encouraged in every possible way the preparation of antidotes; and thus was compounded a mixture which even to-day is still known by the name of “_Mithridaticum_.” For centuries it was a very popular remedy for poisoning by snake-bite. Le Clerc states that one of the first things that the great Roman general Pompey did, after conquering Mithridates and gaining possession of his palace (about 64 B. C.), was to have a careful search made for the recipe of this famous antidote. Upon finding it he was surprised to learn what simple ingredients it was composed of--viz., “20 leaves of rue, a pinch of salt, two nuts, and two dried figs.” The theriacum, which one hundred years later was modeled after the Mithridaticum, contained a great deal of honey and a large number of unimportant drugs, introduced--as Pliny claims--“to magnify the importance of the apothecary’s art, rather than to increase the curative effects of the remedy.”