Since the discovery of tyloses in the secondary xylem of angiosperms, their occurence has been noted only for vessels, although parenchyma cells necessary for their formation are also associated with fibriform elements. Sporadic remarks about tyloses in tracheids related to gymnosperm species, and the only observation on tyloses in angiosperm tracheids has been identified as an error. An anatomical investigation of various magnoliaceous timbers has now demonstrated that a development of tyloses in fibre-tracheids can also be regarded as a part of the normal transition from sapwood to heartwood in angiosperms. More than half of the 22 species studied were characterized not only by tyloses in the vessels but also in the fibretracheids. All the main genera with the exception of Liriodendron show the development of tyloses in the two different xylem elements. Distribution, frequency, and type of tyloses in the fibretracheids are comparable with those in the vessels.—Further investigations on other species of Magnoliaceae are undertaken in order to clarify possible anatomical relations regarding the development of tyloses.