. The morphology of the central cylinder in the angiosperms [microform]. Stele (Botany); Angiosperms; Stèle (Botanique); Angiospermes. JEFFREY : MORPHOLOGY OF THE CENTRAL CYLINDER IN THE ANGIOSPERMS Do they throw any additional light on the difficult problems of the genetic relationships of the group ? Anatomical studies have hitherto been almost entirely neglected by American botanists on account of the wealth of other matters, and that fact will serve as a sufficient justifica- tion for the present research. Were any other needed, it would be afforded by the extremely important phylogenetic
. The morphology of the central cylinder in the angiosperms [microform]. Stele (Botany); Angiosperms; Stèle (Botanique); Angiospermes. JEFFREY : MORPHOLOGY OF THE CENTRAL CYLINDER IN THE ANGIOSPERMS Do they throw any additional light on the difficult problems of the genetic relationships of the group ? Anatomical studies have hitherto been almost entirely neglected by American botanists on account of the wealth of other matters, and that fact will serve as a sufficient justifica- tion for the present research. Were any other needed, it would be afforded by the extremely important phylogenetic results obtained in recent years by English, French, and German palaeobotanists from the study of the fossilized remains of the chiefly vegetative organs of various groups of extinct Cryptogams. The advance of the science of Ecology has furthermore made it less difficult to distinguish between those ceno- genetic features of structure which are the result of the adaptation of plants to their modern environment and those palingenetic traits which serve as an indispensable guide in the interpretation of phylogeny. THE POLYSTELIC TYPE. In his essay on Polystely to which reference has already been made. Van Tieghem' describes this modification of the central cylinder as origi- nating from the pithless monostelic type, by the successive bifurcations of the primitively simple stele. He has referred to it more recently in practically identical ; In studying morphological problems, it is an accepted method of pro- cedure to pass from the lower forms to the higher. This course has been profitably pursued in the investigation of the morphology of sporangia, anthers, ovules, etc., and in the examination of the homologies of the gametophyte in the various groups of vascular plants. Curiously enough, Van Tieghem has given very little attention to the lower forms in his studies on the central cylinder, and still less to their development. In his essay on Polystely he does not des
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