96 BOTANICAL GAZETTE [FEBRUARY 
root origin in pteridophytes, with the exception of Lycopodiales, 
is endodermal, as contrasted with the prevailing pericyclic root 
origin in seed plants. In Marattia the pericycle is not a true peri- 
cycle, since it is composed of sister cells of the endodermis, and 
the phloem may abut on the endodermis. Roots originate 
within the undifferentiated cylinder (fig. 38). Periclinal divisions 
work outward and laterally (fig. 39) and into the cortex which 
forms the periblem of the young root (figs. 40, 41). 
The chief work on apical regions was done under the influence of 
HANSTEIN’s theory of a rigid morphological distinction between 
periblem, plerome, and dermatogen. ScHoUTE (24) has shown 
that the apical divisions do not determine the limits of the tissues 
developed from them. This leads to the view that the character 
of the apical region is determined by the bulk of the organ and has 
no other significance. Whether the transition from the fernlike 
apical cell to a meristematic region has any phylogenetic signifi- 
cance, must be determined by finding whether other bulky plants 
show this variability. Some species of Se/aginella have more than 
one apical cell (Russow 23), but with this exception Marattia is 
unique in this character. 
MUCILAGE DUCTS 
Soon after the solenostelic stage is established, a mucilage duct 
may appear in the center of the pith. A branch from it runs out 
along the adaxial side of each leaf trace, and branches and anasto- 
moses in the cortex of the stem and petiole. FARMER and Hitt (9) 
follow Ktun (19) in ascribing a lysigenous origin to these ducts. 
BREBNER (3) holds to the schizogenous origin in Danaca at the 
upper ends of the ducts. Marattia resembles Danaea in the division 
of the parenchyma cell into four to six without increase in size, 
and the separation of the walls where the small cells come together. 
The contents of the small cells stain deeply with anilin blue, and 
the nuclei, gathered around the point where the cells are to break 
apart, are small and denser than the nuclei in the surrounding 
parenchyma cells. The space left when the walls break apart 
appears empty at first, then becomes filled with a vacuolate 
substance that stains with anilin blue. Later the reaction of this 
