GAMETOPHYTE OF PELLIA EPIPHYLLA 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 206 



A. H. Hutchinson 



(with plates i-rv 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 Pellia 

 is larger than that of Aneura, but its development is very similar, 

 except that the stalk is multicellular, as it is in other Anacrogyneae."' 

 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 antheridia 1 

 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, 



1 Campbell, D. H., Mosses and ferns. New York. 1905 (p. 92). 

 Botanical Gazette, vol. 60] [134 



