Invisible radiations of organisms (1936), and a second record dated 1944 (a reprint or later issue, not in the project folder; check whether the text changed)
Physiology of bacteria (1932); Physik der Milchwirtschaft (1928, with a co-author); Mathematics in bacteriology (1939); Microbes of merit (1945); Über ein neues Terpineol vom Schmelzpunkt 32° (1902, probably his doctoral thesis, full view)
Not him: Kreuzzug gegen den Gral (1964 edition, the other Otto Rahn); Projektierte Himmel (Thomas Rahn, 2019)
Bearing: priority 1. Physiology of bacteria (1932) and Microbes of merit (1945) may contain Rahn's own later view of mitogenetic radiation (does he still hold it in 1945?). Full-text search inside these volumes is the next step.