472 PROF. D. H. CAMPBELL ON THE 
outer cell, so that the young antheridium is separated from the 
surface of the thallus by two layers of cells (fig. 7). About the 
same time, by a partial disintegration of the surrounding cell- 
walls, the young antheridium becomes separated from the 
adjacent cells except at one point, which becomes the point of 
attachment for the pedicel. By the rapid growth of the sur- 
rounding tissue, the space about the antheridium becomes rapidly 
larger and very conspicuous (Pl. 21. fig. 8). 
In all the youngest stages observed, the antheridial cell was 
decidedly elongated parallel with the axis of the shoot, instead of 
vertically as is the case in Anthoceros amd Notothylas, and the 
point of attachment is at the back of the cavity in which it lies, 
instead of at the bottom. Consequently the young antheridium 
(Pl. 21. fig. 8) lies almost horizontally instead of standing upright. 
In both Anthoceros and Notothylas the first division in the 
primary antheridial cell is vertical, and is usually followed by a 
second vertical wall at right angles to the first, so that four 
similar cells are formed which give rise to as many antheridia. 
In Dendroceros, however, the original cell, as we have seen, forms 
but a single antheridium. 
In Anthoceros each secondary antheridial cell divides precisely 
as did the original one, into four, by intersecting vertical walle, 
after which a transverse wall is formed in each cell, which 
separates a stalk-cell from the body of the antheridium. The 
divisions in Notothylas are similar, but less constant, as some 
times the separation of the stalk may be effected by the first wall 
formed in the antheridial cell. 
In Dendroceros, to judge from the small number of the very 
early stages available for study, the first wall (PI. 21.fig.7) separates 
the stalk from the body of the antheridium, after which Je 
intersecting longitudinal walls arise in each of the primary all 
by which they are divided into four equal cells. In the st i 
one of these walls may be suppressed, and the stalk remains ri 
consequence composed of but two rows of cells, as gn 
describes *, but where both are formed, a cross-section of the 
stalk shows four cells arranged quadrant-wise (fig. 10). ble 
The divisions in the upper part of the antheridium resem : 
those in Anthoceros. Fach cell is first divided by à e 
wall (PI. 21. fig. 8) into two, of which the one next the stalk i m- 
smaller and contributes to the basal part of the antheridtu 
* Unters. üb. Lebermoose, Heft 5, p. 33. 
