the Anatomy of the genus Setaginetla , Spr. 83 
is capable of another interpretation, which perhaps more satis- 
factorily meets the case. 
The sheathing-cells of the glossopodium vary much in 
shape. Most frequently, as in S. grandis , .S'. Martensii , 
.S', caulescens , .S'. viticidosa , &c., they are in the form of elon- 
gated staves or bars, curving round to meet at what may be 
termed the base of the foveola ; whilst in other cases, e. g. 
*S. spinosa, they are short cubes. 
The ligule of .S', oregana (Fig. 19) and S. rupestris deserves 
a word of explanation. In these species the free margin of 
the ligule scarcely appears above the edge of the very deep 
pit in the leaf in which it is seated. The vascular bundle of 
the leaf does not present any enlargement, but the radiating 
cells intervening between it and the sheath of the glosso- 
podium are strongly sclerotic. The sheath consists of two 
rows of stave-like cells, and the glossopodium of two rows of 
right triangular prisms. The leaf-tissue, however, grows up 
and round the free portion of the ligule, so that a deep pit is 
formed, the cells of which have no connexion with the ligule. 
These appearances are illustrated in Fig. 19. 
B. The Development of the Ligule. 
In tracing the development of the ligule, I confined myself 
to the study of the shoots of two species, viz. .S', spinosa and 
.S'. Martensii\ partly because I had the advantage of com- 
paring my own preparations with the large series kindly lent 
me by Professor Bower, and partly because, from an exami- 
nation of the adult state of the ligule in numerous species, 
I felt that the differences in mode of development were un- 
likely to be very fundamental. 
.S', spinosa. The ligule, as in all the species of this genus, is 
multicellular in origin. If careful longitudinal sections be made 
of the growing-point, the ligule may be distinguished first 
about the level of the third or fourth leaf as a fairly distinct 
swelling immediately at the base of the leaf. The swelling 
consists of a short ridge about six or eight cells in length 
in the plane of the leaf-face, and three broad, that is to say, 
G 2 
