Alkaloids, Organic Bases, or Organic Alkalis, a series of bodies of vegetable origin which are distinguished both by their similarity in properties to the alkalis proper, and also by their toxicological importance. They contain, as a rule, Carbon, Hydrogen, Oxygen, and Nitrogen; though in some cases the oxygen is absent. They have, for the most part, a marked alkaline reaction. Many of them are exceedingly poisonous. A very large number of natural alkaloids have now been discovered. For the most part they are crystalline solids which have a pronounced physiological action. Many of the most powerful and useful drugs are alkaloids; among such are aconitine, atropine, caffeine, morphine, quinine, physostigmine, pilocarpine, and strychnine. Alkaloids act as bases, forming salts with acids, thus we have sulphate of quinine, citrate of caffeine, hydrochlorate and acetate of morphine, and so on.