232 BOTANICAL GAZETTE [APRIL 
contents. These parts can be traced later to the corresponding 
parts of the axial bundle. Behind the sporangium the xylem 
spreads out into a broad band in which the amount of xylem 
parenchyma is greatly increased, and the tracheids are in five or 
six scattered groups. Above the sporangium .the xylem con- 
tracts again into a cylinder, and lies between the cornua of the 
ligule base. A more striking change occurs above the ligule 
where the xylem elements suffer an extreme diminution, there 
being in that region in J. echinospora only a single imperfect 
central tracheid surrounded by a sheath of parenchyma (jigs. 9, 
70). Occasionally in 7. echinospora, and usually in J. Englemanni, 
two, sometimes three, other such groups can be traced up the 
leaf. 
The phloem is best represented in the chlorophyll-bearing 
portion of the leaf. It there consists of two strap-shaped bands 
on the dorsal side, more or less united by their edges, so as partly 
to surround the xylem. In less distinct form the phloem may 
be traced downwards to the region of the central bundle. 
The development of the ligule was accurately described by 
(Hofmeister 1), and also by Hegelmaier (1). The latter refers 
its origin to more than one cell. Since the former gives. few 
figures, however, and the latter none, I shall again briefly 
outline the course of growth and illustrate it with a few 
drawings. The ligule Originates from a single large vesicular 
cell protruding from the ventral face of the leaf rudiment. Pro- 
vision for its rapid growth is shown in the large size of the nucleus 
of this cell, and the density of the cytoplasm (figs. 12, 13). The 
first division is always parallel to the face of the leaf ( figs. 14; 
75), and usually the second division is parallel to the first. 
The ligule of Z. lacustris is described as passing through a fila- 
mentous stage; but in 7. echinospora and J. Engelmanni it is 
hardly worth while to distinguish such a stage, for the filament 
never consists of more than three cells. ~The terminal cell then 
divides in a vertical plane at right angles to the first wall ( /igs- 
76, 18). Other vertical divisions follow until the ligule has 
become a plate of cells of very regular arrangement. igs. 7 6 
