June, 1922] 
DUPLER REBOULIA HEMISPHAERICA 
291 
examination of the receptacle in transverse and vertical sections shows, 
however, a tendency toward a centrifugal origin of the sex organs. Young 
antheridia are found not only lateral, but even posterior to the oldest ones 
(figs. 14, 15, 23, 24). While, as shown in figure 23, there may be two general 
strands of sex organs, giving a lunate group, the youngest antheridia occur 
at the four points marked "x," indicating several possible points of origin 
of the sex organs. The oval disc (fig. 24) is not so definite in points of 
origin, yet shows a centrifugal development. That this is not merely due 
to different rates of development is shown by sections of young receptacles 
(PI. XIV, figs. 26-29). Figures 26-28 show a young disc in whose develop- 
ment both anterior and posterior apical cells seem to be active, the oldest 
antheridia being near the center of the disc and the younger ones near 
the anterior and posterior margins. Oblique sections (fig. 29) and vertical 
transverse sections of the thallus, through the young disc, show the same 
condition. While the first antheridia may arise in close connection with 
the growing point of the thallus, the later ones, especially in a lunate group, 
may be far removed from the apex of the thallus, arising from apical cells 
along the margin of the disc (figs. 30, 31). 
Development. The development of the antheridium, as a general rule, 
is essentially as given by Haupt (16), the initial arising as a papillate cell 
(PI. XIV, fig. 25) which cuts off a basal cell (fig. 28). Other transverse 
divisions (fig. 29) result in a short filament, usually of four cells (fig. 32) — • 
the limit, according to Haupt, but there may be as many as six (fig. 33), 
agreeing with the situation in Fimbriaria as described by Campbell (3). 
Vertical walls usually appear first near the center of the filament (fig. 34), 
and divide the segments into quadrants (fig. 41). Periclinal walls (figs. 
35, 38-40) differentiate the wall from the primary spermatogenous cells. 
Transverse and vertical divisions of the basal portion build up the stalk 
(figs. 35, 38-40) which may become comparatively long (fig. 19) and is 
usually somewhat coiled within the chamber (fig. 16). 
In some cases the vertical wall of the terminal cell is strongly inclined 
(fig. 36). The next wall, cutting at an angle to this, produces an apical cell 
with two cutting faces from which a few segments may be cut off (figs. 
38-40). The writer has also observed this occasionally in Chomiocarpon 
and Marchantia. This feature suggests the antheridium of Sphagnum 
and of the Bryales. Inner cells from these segments make their contribution 
to the spermatogenous tissue (figs. 39, 40, 16). Cross sections of the young 
antheridia show that in addition to the usual method of differentiation of 
the wall and primary spermatogenous tissue (figs. 41, 42), interesting varia- 
tions may occur (figs. 43, 44), in some cases resulting in only two primary 
spermatogenous cells in the segment and resembling the condition found 
in the Jungermanniales (fig. 44). Hutchinson (20) showed a considerable 
variation in the development of the antheridium of Pellia epiphylla, both 
the so-called Marchantia and Jungermannia types occurring. These 
