TOXICOLOGY

the science dealing with poisons. Its main branches deal with the chemical nature of poisons, their origin and preparation; their physiological action and the tests by means of which their presence may be detected; the pathciogical changes due to their presence and the recognition of them by post-mortem evidences; their chemical reactions with a view to the determination of antidote and the physiological action of the latter. Since the time of Virchow, Pasteur, and others, the science has become much more intricate, chemotherapeutics being largely devoted to the discovery of toxins and antitoxins, which may be roughly described as the poisons excreted by bacteria and those which are antidotes, either in a chemical sense or as poisons for the bacteria. This subject views the matter as warfare between germs and the cells of living creatures, carried on largely by means of excreted poisons. The investigation tends to a ume the form of research into the molecular structure of the chemical concern. See Poisons.