402 BOTANICAL GAZETTE [DECEMBER 
The cortex is exceedingly thick, forming by far the main 
bulk of the root, and consists of large celled sclerenchymatous 
tissue. The cortical cells diminish in size towards the periphery, 
and become thicker walled. In TZ. darbara, however, there is a 
discontinuous ring of exceedingly thick walled brown scleren- 
chymatous cells immediately surrounding the vascular axis. 
The endodermis, which is continuous with that of the stem and 
leaf, is very pronounced in all of the species, and is at once 
noted by the radial dot, and by the fact that its cells are filled 
with tannin. In the second particular, exception must be gener- 
ally made of O. Claytoniana. 
The stele is comparatively small, and is typically protostelic, 
since there is no pith. The wood has a narrow elliptical form, 
consisting mainly of very large scalariform tracheids. At each 
end of the ellipse there are a few small protoxylem elements, 
which are especially evident in the young root, and which have 
no connection with the protoxylem of the stem or leaf. The 
root, therefore, is diarch. There are likewise two bundles of 
phloem alternating radially with the bundles of xylem. In all 
of the Osmundas, however, | have observed triarch steles in the 
larger roots, which exception is of comparative frequence in 0. 
cinnamomea. The phloem consists of two flat bundles or bands. 
These bands are made up chiefly of thin walled sieve tubes 
which are of the same kind as‘occur in the stem. None of them 
are ‘‘quergestreckt.” The phloem is separated from the xylem 
by three or four rows of parenchyma, and from the endodermis 
by a two rowed parenchymatous pericycle. 
DEVELOPMENT OF THE TISSUES FROM THE GROWING POINT. 
In discussing this subject there are two points in particular 
which will receive special consideration: (1) the statements of 
Strasburger and Zenetti regarding the origin of the endodermis, 
and (2) the real nature of the “‘quergestreckte Zellen.” 
The determination of the relation of the tissues to the apical 
cells seems of little concern, and moreover in the study of the 
apical region of the growing point there are serious difficulties. 
