142 BOTANICAL GAZETTE [AUGUST 
has been reached by several lines of development; hence close rela- 
tionship with “‘Acrogynae”’ is not necessarily implied: If the 
development of the antheridium may be taken as a basis of classi- 
fication, it would seem that Pellia arose from the main line of 
advance before the two branches, Jungermanniales and Mar- 
_chantiales, became separate, even before the archegonium and 
antheridium became definitely differentiated in their methods of 
development. 
From Pellia we have evidence regarding the relation of Jun- 
germanniales and Marchantiales. There is in the life history a 
transition from the cuneate apical cell of Marchantiales form to the 
lenticular cylindrical apical cell found in certain Jungermanniales; 
similarly, the antheridium, already discussed, affords strong evi- 
dence for the existence of such a relation. The evidence tends to 
indicate that Marchantiales are primitive and that Jungermanniales 
are derived. 
Summary 
The antheridium.—The development varies. The dominant 
method is that characteristic of Jungermanniales; forms occur, not 
infrequently, which are like the antheridium of Marchantiales, while 
others are like the archegonium in their early development. 
The archegonium.—The archegonia are produced from cells of 
the apical group and occur in an archegonial pocket. The diver- 
sities from the regular form are few; the large number of neck 
canal cells, the extreme development of the cap, the frequent 
reduction of the number of tiers of neck wall cells to five, and 
the somewhat massive venter may be noted. The outer cell of the 
two resulting from the division of the archegonial initial divides 
horizontally before the vertical wall is formed. 
Methods of growth——Several periods of growth may be recog- 
nized, each having a specific method of growth: the massive; the 
period of the cuneate apical cell extending until antheridium 
formation; the period of the lenticular cylindric apical cell, or the 
antheridial period; the period of regional apical growth, or the 
period of archegonium production; and the second period of mas- 
sive growth, or the period of sporophyte dependence. 
