332 BOTANICAL GAZETTE [NOVEMBER 
base of the underleaf. These two rows of cells separate slightly 
at their free ends, which are. tipped with the papillae, but 
coalesce throughout the greater part of their length. In this 
way a linear underleaf is formed, slightly bifid at the apex. In 
O. prostratum ( figs. 59-62) a few longitudinal (or oblique) divi- 
sions sometimes occur near the base, and in O. Sphagni ( fig. 41) 
these divisions are more frequent. Through these longitudinal 
divisions an underleaf may acquire a subulate form, but it is 
always much longer than broad. In the second type of under- 
leaf the development begins in the same way, but the order of 
cell division is much less regular, longitudinal divisions tending 
to set in very early. The adult underleaves in consequence vary 
greatly in form, being sometimes distinctly bifid and sometimes 
rounded or truncate at the apex. In many cases the breadth 
equals or exceeds the length. These variations affect the under- 
leaves, whether they remain small, as in O. Gibbsiae (figs. 33; 34) 
O. denudatum (figs. 37, 38), and some forms of O. Macounit 
jigs. 9, IZ, 72), or attain a considerable size, as in the other 
forms of this same species ( fig. 70). 
As the underleaves develop, some or all of their cells give 
rise to a series of slime-secreting papillae, similar in all respects 
to the primordial papillae. In a young underleaf these may be 
found in all stages of development. A papilla begins as an out- 
growth from a cell and soon becomes swollen at its extremity. 
In most cases a wall is formed at the base of the papilla, cutting 
it off from the cell. In rare cases this wall is suppressed and 
the cell simply forms a part of the papilla. Usually the papil- 
lae are limited to the margin of an underleaf, but occasionally 
they grow out from the postical surface as well. This is fre- 
quently the case in O. Sphagni, where it may even be difficult to 
distinguish the permanent cells of the underleaf on account of 
‘the crowded papillae which cover them. In our other species 
one or two papillae may occasionally be found on the postical 
surface. In rather rare cases two papillae may grow out from a 
‘single cell. The later development of the papillae has been 
-briefly described by Goebel * for Calobryum Blumei. A layer of 
76Ann. Jard. Buitenzorg g:15. 1891. 
