136 BOTANICAL GAZETTE [AUGUST 
The differences in these antheridia are emphasized by the 
fact that in the first form (fig. 8) there are two spermatogenous 
initials, paired as in Jungermanniales; in the second form there are 
four, arranged in the form of a quadrant (fig. 10), as in Marchanti- 
ales; and in the third and fourth there is but one spermatogenous 
initial (figs. 10, 24, 25). 
That the structures described above are developing antheridia, 
and not archegonia, is evidenced by their position and by the pres- 
ence of an individual involucre. The antheridia are single and 
dorsal, while the archegonia are grouped in the terminal pocket. 
Archegonium 
The position of the archegonial group is of considerable mor- 
phological importance. CAMPBELL, with reference to the work of 
JANCZEWSKI, states: “‘The archegonia are formed in groups just 
back of the apex but he [JANczEwsk1]| does not seem to have been 
able to detect any relation between them and the apical cell such 
as obtains in Aneura, but it is possible that such a relation does 
exist.” As mentioned above, the archegonia are terminal and 
inclosed in a “‘pocket,’”’ which is formed by a cup-shaped involucral 
growth. As will be described more fully, the archegonia arise 
from an apical group of cells, any of which may become an arche- 
gonium initial. There is no regular succession in the formation of 
archegonia; apparently old and young organs are indiscriminately 
intermingled. Since the apical group ceases to function as such 
after the production of archegonia, P. epiphylla may be regarded 
as truly acrogynous. The involucre is produced by cells which are 
cut off laterally by the apical group (fig. 40), and pushed out very 
much as the wings during the previous period of growth; in this 
event, however, the lateral cells are forced out on all sides to form a 
complete inclosure. 
The structure and development of the archegonium conforms, 
in general, to the characteristic liverwort form. Some specific 
characters may be noted? “After the archegonial mother cell is 
cut off it does not divide at once by vertical walls, but a pedicel is 
first cut off [fig. 31]; after which the upper cell undergoes the 
? CAMPBELL, D. H., Mosses and ferns. New York. 1905 (p. 90). 
