Anatomy of Spartina Townsendii . 
339 
the silica-cell lies, partly embraced by the upcurved ends. This is shown 
in Fig. 1,3, 4, and 6. This type appears wedge-shaped in longitudinal 
sections of the leaf. The blunt end is outwards (Fig. i,y, si) and covered 
by a very thin wall, difficult to distinguish owing to its delicate structure 
and the refraction cf the mass beneath. The silica body occupies the 
greater part of the cell. It is invested by a thin layer of protoplasm and 
blocks the entire upper and wider end of the cell cavity by which its 
outline is determined. It is easily recognizable both by the presence of 
small included air-bubbles, and by its resistance to stains. These cells 
develop from ordinary short, rectangular ones, and are most abundant in 
the upper outer epiderm of thes heath, where, immediately below the 
articulation, they equal the long cells in number. They cease at the point 
gc 
Fig. 2. 1. Surface view of special type of stoma with forked papillae ( fpa ) ; simple papillae 
{pa). 2. Transverse section through swollen vesicular ends of guard cells. 3. Transverse section 
near the middle and thickened portion of guard cells ( gc ). 
where the break appears later. A few occur along the ridges of the blade 
and on the peduncle, but none have been found on the rhizome, the stem, 
or the first-formed leaves. Their distribution lends strong support to the 
view that they add to the rigidity of the plant, which is aided largely 
by the closely investing leaf-sheaths, on whose outer surface they are most 
numerous. 
Stomata , The stomata belong to the characteristic grass type. The 
walls of the middle portions of the guard cells are so thickened that the 
cavities connecting the swollen ends are reduced to narrow passages, as 
in Fig. 2, 3. The slit is slightly longer than these rigid bridges, which 
are carried bodily apart by the swelling of the vascular thin-walled ends 
(Fig. 2, 2). 
The most active stomata are those situated on the adaxial surface of 
the leaf over the loose chlorenchyma, where they are more numerous 
than in any other part of the plant. There they occur in two, rarely 
