[100 years roentgen rays--a discovery conquers the medical world]

In the second half of the nineteenth century the prerequisites for research on the discharge of electricity in gases and the related phenomena were fulfilled. The first gas discharge tubes are associated with names like GeiBler, Hittorf, Crookes, Goldstein, Lenard and Hertz. These researchers studied the electrons escaping from the cathode, magnetic and electrical influence, chemical results, loss of energy and heating up of the anode. Lenard and Jackson were the first to describe phenomena outside the tube, but related the effects to electrons. It was W.C. Roentgen who discovered the ¿unknown rays¿; he systematically measured their penetrating properties and described them a short time thereafter. The scientific world was ready for this discovery, and the new of Roentgen's findings spread across the world in a matter of days, followed by intensive development of this innovation. The first and most important 35 years of development of the different types of X-rays tubes are described.