BRIEFER ARTICLES. 
The origin of the sexual orgazis of the Pteridophyta.—One of the 
greatest difficulties encountered in attempting to determine the homol- 
ogies existing between bryophytes and pteridophytes has been the 
apparently radical differences in the structure of the sexual organs, 
especially the archegonium. The latter in all pteridophytes is remark- 
ably constant in structure and always has the venter completely im- 
mersed and the neck composed of four rows of cells. In the bryo- 
phytes the venter is usually free, and the neck composed of six (some- 
times five) rows of cells. These differences are especially noticeable 
when the leptosporangiate ferns are compared with the bryophytes, 
and so long as the former were regarded as primitive forms it made 
all attempts to connect them with any group of bryophytes seem 
hopeless. 
When, however, the eusporangiate pteridophytes are examined, It 
is seen that they show certain points of resemblance in the structure 
of the sexual organs to one order of the Hepatice, the Anthocerote®, 
which has long been admitted to have the greatest affinity to the pterid- 
ophytes in the structure of the sporogonium. An examination of 
several members of this order in connection with the study of the de- 
velopment of J/ara/tia, one of the eusporangiate ferns, led the writer 
to venture on a possible explanation of the origin of the archegonium 
of the latter from forms resembling the Anthocerotee. A further ex 
amination of other eusporangiate ferns, as well as Eguésetum and the 
Lycopodinez, makes it seem likely that the statements made with ref- 
erence to Marattia are applicable to all pteridophytes, and that ho- 
mologies in the antheridium of the eusporangiate pteridophytes and 
Anthocerotez can also be assumed with much probability. 
In all bryophytes there are formed in the archegonium mother-cell 
three nearly vertical walls which intersect so as to enclose an axial 
cell from which are formed the egg and canal-cells, as well as a term! 
nal cell, the cover cell. This latter in the Hepaticze always divides 
by cross-walls into four cells which may occasionally undergo one OF 
two further divisions. The axial row of cells is surrounded by three 
peripheral cells, which divide usually once by a vertical wall. Some- 
times one of these fails to divide so that there are but five in all. 
These six (or five) cells are the initials for the corresponding rows of 
cells in the neck of the mature archegonium. 
[76] 
