VITTARIA LINEATA 199 
opment as soon as visible. Hairs are produced profusely, origi- 
nating .5 mm. from the tip. The roots quickly penetrate the bark 
of the palmetto tree to which the plant is attached, and as they are 
exposed to the light in various places form chlorophyl. 
The root hairs measure from 0.6-4.5 mm. in length and 5 
.0299 in width. The hairs seldom form cross walls but occa- 
sionally branch near the apex, although the branches do not 
attain any considerable length. The roots branch profusely: 
one 13 mm. long produced 6 branches and 1 branch 7 mm. long 
produced 3 branches (f. $8) The central cylinder of the root 
is apparently diarchic (f. 86, 87) and the endodermis is plainly 
differentiated. The cortex consists of 4-6 layers of large cells 
with strongly differentiated walls; the outer rows show this stri- 
ation less plainly however. The outer layer immediately in- 
ternal to the epidermis contains large numbers of crystalline 
bodies connected with their inner walls (f. 87, 88). The epi- 
dermal cells are large, the thin outer walls being pressed inwardly 
in many instances. 
STERILE Leaves. — The leaves of Vittaria lineata show pro- 
gressive variation in form and venation (f. 89-95). Those which 
arise earliest are spatulate and have a single central vein, later 
they show a branching venation ) $9, 93). The laminar por- 
tion of the first leaves is flattened and the cross section does not 
show such complete dorsiventral differentiation as may be found 
in the leaves arising later. They are but slightly curved when 
they emerge from the scales, and the curvature soon disappears. 
The epidermal cells are somewhat longer than broad with wavy 
walls (f. 97). Among these cells are a few elements with 
pointed ends and wavy walls (/. 98a), which are most abun- 
dant near the fibrovascular bundles. The epidermal cells gener- 
ally contain chlorophyl with the exception of the hyaline border. 
The latter is composed of elongated elements with oblique end 
walls (f. 96a). The epidermal cells of the petioles are pros- 
enchymatous and rarely have wavy walls. Stomata occur on the 
under side of the lamina but do not occur immediately external 
to the veins. Numbers of club-shaped bodies, composed of three 
cells (f. 97a), resembling glands, are to be found on both sur- 
faces. Scales arise on the basal portion of the earlier leaves di- 
