"The two present treatises follow on from a treatise of the author published in 1890. The first of these two treatises contains mainly the derivation, exposition and meaning of the linear transformations of the sg. Klein 's configuration, which has been studied in more detail in the earlier treatise. These transformations are treated group-theoretically by W. Reichardt and H. Maschke using Klein 's line coordinates, in particular the generating substitutions have also been established by both. In the following developments the geometrical interpretation and differentiation of these completely set up transformations, namely of the collineations and correlations, is preferably taken into account and the indication of the tufts and nets of surfaces of second degree, the Scha.