1921] HAUPT—REBOULIA 71 
Further development of the archegonium is typical (figs. 17-20). 
The cover cell divides by a vertical wall which accompanies the 
first division of the primary neck canal cell. No evidence was 
found to lead to the suspicion that earlier than this stage the 
cover cell contributes to the development of the neck cells. Nu- 
merous mitotic figures in the neck cells prove that they increase in 
number by intercalary divisions. 
The ventral canal cell and egg are formed 
from the primary ventral cell rather early (fig. 
20), and the former is unusually small. As soon 
as the egg is formed, the venter of the archego- 
nium develops 2 layers of cells, and this con- 
dition prevails until after fertilization. The 
archegonial stalk is short, and the neck invari- 
Fics. 18~20.—Older archegonia: fig. 18, formation of primary neck canal cell 
and ventral cell from central cell, 790; fig. 19, division of primary ventral canal 
cell, X 790; fig. 20, older archegonium showing formation of ventral canal cell and egg, 
790. . 
ably curves outward and upward (fig. 21) so as to facilitate the 
entrance of the sperms, as in other forms in which the archegonia 
are borne similarly. The mature archegonium contains 18-20 neck 
canal cells which break down soon after their formation. The neck 
in all cases shows 6 cells in cross-section, as among other Marchan- 
tiales. JANCzEWSKI states that the number of neck canal cells in 
Reboulia is 4. He probably observed a nearly mature stage like 
fig. 20. 
