NortH Haven Sanp PLatns 589 
surface but are found in one or two rows of cells between the 
nerves of the lower surface. The guard-cells of the stomata are 
very narrow and have thick walls with the lumina nearly closed. 
ANDROPOGON FURCATUS.— Superior surface covered by a layer 
of large colorless parenchyma or bulliform cells. Over the larger 
mestome bundles these cells are very small or the layer is inter- 
rupted entirely. Cells of the inferior surface are also colorless 
but much smaller than those of the upper surface. On both sur- 
faces, especially over the mestome bundles, certain cells are ex- 
tended into short, stout, unicellular hairs. Subepidermal strands 
of stereome occur opposite the larger mestome bundles on both 
the upper and lower surfaces; small strands occur below nearly 
all of the smaller mestome bundles. The keel is chiefly com- 
posed of stereome-cells having very thick walls, in many cases 
almost obliterating the cell lumina. A small strand of stereome 
occurs on the upper side of the midrib and on each side of this 
Strand are situated several rows of large bulliform cells. Each 
small mestome bundle is surrounded by a sheath of large paren- 
chyma-cells from which radiates a row of green palisade-cells con- 
nected between the bundles with cells of similar tissue. Bundle 
of midrib nearly enclosed by sheath of parenchyma-cells, supple- 
mented by cells of stereome on the leptome side. Leptome and 
hadrome separated by a row of thick-walled cells, which are prob- 
ably tracheids. Elements are not clearly differentiated in the 
small mestome bundles. Stomata are abundant in the grooves of 
the inferior surface. 
SPOROBOLUS VAGINAEFLORUS.— Rolls into a cylinder on drying. 
A group of five (one very large and four smaller) bulliform cells 
Occur between the mestome bundles on the superior surface. A 
similar arrangement is found on the under surface, though the 
cells are smaller. Larger mestome bundles are each provided 
with a sheath of colorless parenchyma-cells and all bundles have 
Sheaths of large, greenish-yellow parenchyma-cells with rather 
thick walls. Above and below each mestome bundle occurs a 
strand of stereome tissue, the one on the lower side being much 
broader than the one on the upper side. In some of the larger 
bundles having a stereome sheath the parenchyma sheath is in- 
terrupted next to the stereome strands, the interruption occurring 
