In their contribution to the first edition of this Handbook, entitled "The Teeth," LEHNER and PLENK (1936) discussed the tissues constituting the "perio dontium" rather briefly. In contrast to the detailed paragraphs dealing with, for example, enamel and dentine, the section (about 40 pages and 20 illustra tions, mostly drawings) devoted to periodontal tissues failed to provide a factual review and summary of the contemporary knowledge and latest developments in research on the various components of the periodontium. Instead, much of the text was an attempt to arrive at conclusions from often...