1915] BRYAN—ARCHEGONIUM OF SPHAGNUM SUBSECUNDUM 45 
two segments last formed becomes the initial of a secondary 
archegonium, while that portion of the apical cell above and not 
included by them is the initial of the primary archegonium (fig. 2). 
Fig. 3 shows this in cross-section. A few examples have been 
noted where one of the secondary segments, after making several 
divisions, has for some reason been checked and remains as a 
slight projection on the base of the mature primary archegonium. 
In some cases only the last formed segment develops as a secondary 
archegonium; while still more rarely no secondary. archegonia 
are formed at all, the apical cell becoming the initial of a single 
archegonium (fig. 5). 
THE PRIMARY ARCHEGONIUM 
The primary archegonium shows a remarkable variation in the 
manner of its early divisions. The first wall may be transverse 
(fig. 6) or slanting (fig. 4). If the first wall is slanting, the second 
may be transverse (fig. 5). However, by the examination of a 
large number of slides one may recognize two general types of 
development. A filament of cells, usually 4 or 5 in number, may 
be formed by successive transverse divisions of the apical cell 
(figs. 6-9). Four or five cells may be produced by the activity 
of an apical cell with two cutting faces (figs. 11, 12); this is prob- 
ably the most frequent method. Between these two extremes there 
may be various mixtures of planes. An interesting intermediate 
condition in which the walls do not quite intersect is shown in 
figs. 10 and 13. 
At this point the question may be asked, Why are not figs. 6-9 
merely the development of an apical cell with two cutting faces 
seen at an angle of go° from the plane represented by figs. 11 and 12? 
This matter has been carefully examined and the following facts 
Presented as an answer. Unquestionably the walls may have 
such an appearance, but the test is their behavior under the oil 
‘mmersion lens. If the walls are transverse, they remain steady 
on focusing up and down; but if of the kind formed by an apical 
cel with two cutting faces, they swing in a characteristic 
Manner as one changes the focus. Frequent examples of this 
have been found, as well as those in which there was no shifting. 
