1904] JOHNSON—MONOCLEA 197 
forming cells are thus not sister cells of the spore mother-cells, but 
rather of cells which give rise to several of the latter. The longitudinal 
grouping of the spore mother-cells in figs. 47 and 4g indicates their 
origin, and the pointed, terminal mother-cell of each row in jig. 47 
recalls the spindle-like form of the parent cell. 
When the capsule is about three quarters grown, that is when it 
is 3 or 4™™ long, the spore mother-cells round off from one another. 
Soon afterward they assume the usual four-lobed form (fig.49). Then 
follows the division of the nucleus and the separation of the spores 
of the tetrad in the usual manner. The mature spores are uninucleate, 
nearly globular, 16 to 18» in diameter, and have a thick, reticulated 
wall (figs. 51, 52). 
The elaters continue to elongate as the spores are maturing and 
ultimately reach a length of rs0u. + They are about 8» in diameter 
in the middle, and taper to a rather blunt end in each direction. 
Some time after the individual spores are formed two rather closely 
twisted, spiral, thickening bands appear in each of the elaters (jig. 50). 
These bands are about as wide as the interspaces of thinner wall left 
between them. One of the bands often disappears considerably 
before the other as the end of the elater is approached. No grouping 
of the elaters or attachment to the wall of the capsule was noticed, 
except the attachment of a few scattered elaters at the base of the 
capsule to the wall near the end of the seta. 
The elongation of the seta occurs after the capsule is practically 
Tipe, and the latter opens soon after being pushed out of the involucre. » 
The opening seems to proceed gradually, and the escape of the spores, 
aided by the twisting and untwisting of the elaters, is thus distributed 
over a considerable portion of time. 
CONCLUSIONS. 
HooKer (’20), GorrscHe (’58), and LEITGEB (’77, p. 62, and ’81, 
P. 132) all recognized the similarity of Monoclea in size and habit to 
the Marchantiaceae, and Lerrcr noticed the likeness in the structure 
of the antheridium and the male receptacle to those of the same group 
of liverworts. But the form of the involucre, the structure of the 
eo, and especially the absence of air chambers and (as 
ey believed) of tuberculate rhizoids, led all these workers to keep 
onoclea out of the Marchantiaceae. 
