(2) For the theoretic postulate for “biology” and disregard of this posttktion in practice, a few samples may be t on the, other hand, he advocates ia his ~~uistia and in Scheff (Vol. 6) the use of silk to perform quite extensive to ments, although I have caRed attention to the possibility of pro resorption, particularly by using silk (Ztschs. f. Stomatol. p. 614, Schwarz recommends on several ocoasions the use of bite“In the practice of orthodontia bite-caps, analogens to the caps u&d in the experiments of Gottlieb and Orban, are often used. Atten&ion should be called to the various forms of inclined planes, to the funotiona bronght about by masticatory exercises, and to other orthodontic which cannot be omitted from modern orthodontic. therapy.” Tx farther on he describes the destructive results of these ctaps “that are q&e anaiogous to those used by Gottlieb and Orban: In using strong f&rees, w&& crush the tissue, the tissues which are deprived of their vitality aru eliminated by intense resorption of the peripheral tissues which have not lost their vitality, in order to permit .further movement of the tooth.” Should not the postulate for biologic treatment be applied to all to& movements, therefore, also for the shortening of teeth? Sho&b not the postulated 20 gm. maximum pressure (Schwarz) also be valid for the slmrteningt Are the strongest intermittent forces of mastication permissible &at here? Are not the manifold damages, ascertained by animal ~~~~~~ su&!eient warning ? Also the “sprdngs for d&W moverned” are recommended by because of their ‘ ‘rational working. ” In his already mentioned easn tributioa and in Scheff (Vol. 6) he makes a report on several eases movement of molars by using this spring. For this pupiaur~ a13 ~~~~~~ teeth, and also as many of the permanent teeth as are present anterior to the