[Milestones in virology].

The "milestones" of virology try to depict the development from variolation to construction of hybrid viruses. Not only single observations or detections are listed, in contrast, this is an attempt to delineate from single events conclusions for the more general development of virology. Because of the increase of specialization in experimental sciences, it is often difficult for researchers to realize the roots of their present problems. Often, earlier conclusions are being overlooked, from which recent experimentations have been delineated.