GAMETOPHYTE OF PELLIA EPIPHYLLA 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 206 
A. H. HutcHInson 
(WITH PLATES I-IV AND ONE FIGURE) 
Three of the species of Pellia—P. epiphylla, P. calycina, and 
P. endivaefolia—show morphological differences, especially with 
respect to the apical cell, which would suggest a generalized or 
possibly an unstable ancestral form. No detailed study of any of 
these species has been reported. During the investigation upon 
which this account is based, it has been found that in P. epiphylla 
not only are there transitions in the method of growth, but also that 
the development of the antheridium may follow any one of several 
divergent lines. 
Antheridium 
It has been generally accepted that ‘‘the antheridium of Pella 
is larger than that of Aneura, but its development is very similar, 
except that the stalk is multicellular, as it is in other Amacrogyneae.””* 
In addition to this method of development, P. epiphylla shows 
young antheridia having characters of Marchantiales; moreover, 
the spermatogenous initials may be cut out in the same way as the 
primary axial cell of the archegonium. 
The division of a dorsal cell, the third or fourth from the apical 
cell, by a horizontal cross-wall is the first evidence of an antheridial 
initial. The outer of the two cells formed divides again, giving the 
three cells of the antheridial row—the basal cell, the stalk initial, 
and the outer cell; the latter by successive divisions gives rise 
to the wall cells and spermatogenous cells. Meanwhile, the dorsal 
cells, immediately surrounding the antheridial group, divide and 
become papillate, thereby producing a ring-shaped involucre 
(figs. 2, 3). The outer cell of the antheridial group divides next. 
The position of the wall is significant; if it is vertical and median, 
* CAMPBELL, D. H., Mosses and ferns. New York. 1905 (p. 92). 
Botanical Gazette, vol. 60] [134 
