LAUSR

As early as 1943, the German physician Helmut Ruska visualized the virus of varicella and zoster (at that time, he was not completely certain whether the virus was the same) by the newly developed electron microscope; he is regarded as the discoverer of this virus. Here, we present a translation of his classical paper into the English language. In our introduction and commentary to his paper, we discuss the significance of Helmut Ruska's work for the development of virology, his distinction between the varicella, zoster, and herpes virus group on one hand and poxviruses on the other, as well as the development of imaging techniques which have refined or substituted for electron microscopy of viruses and virus‐infected cells.