The volume contains Birken's correspondence with three younger members of the Pegnitz Flower Society Magnus Daniel Omeis (Nuremberg, Vienna, Altdorf), Joachim Heinrich Hagen (Bayreuth), Sebastian Seelmann (Regensburg) and with the Breslau rector Georg Wende. Birken was an important promoter of the younger members, while Wende ensured that one of the thirteen women Birken nominated entered the society.