Boundary structure of bounded symmetric domains

Let D be a bounded symmetric domain realized as the open unit ball of a com plex Banach space E and denote for every a is an element of D by s(a) the s ymmetry of D about a. We show that for every boundary point c is an element of partial derivative D the locally uniform limit s(c) := lim(a-->c) s(a) exists as holomorphic map s(c) : D --> E and has values in the boundary par tial derivative D of D.