The Kath-branch can be devided in two parts:
1. The father's side of Hertha Martha Kath: Otto Paul Emil Kath. He
came from Western Pommerania. This region is Poland today. According to
that, ancestrical researches are difficult. Deocuments are either
destroyed or not really sorted in various archives in Germany, Poland or
somewhere else. The data on my ancestors are based on the proof of
ancestors of my grandmother and a grand aunt.
Some years ago I was visiting the related villages during vacation. Some
impressions and descriptions about the villages you will find here:
Pomerania
2. The mothers side of Hertha Martha Kath: Otto Paul Emil Kath married 1898 in Eichstetten Ida Diebold. She came from southern Germany. Her parents can be devided in the father's side, who came from Jungingen/Hohenzollern and were katholic. Her Mother came from Eichstetten in the Rhein valley. The records from Eichstetten are available at Archion and there is a very good village familiy book about Eichstetten, "Ortsfamilienbuch Eichstetten, Eichstetten am Kaiserstuhl 1644 - 1900" from Kurt Heinzmann (893 pages) availabe.
A detailled list of ancestors you will find in a kekule-sorted list.