Allen—Spermatogenesis and Apogamy in Ferns. 19 
mously. The disuse of the motile male cells in this species has 
not, however, been accompanied by their degeneration. 
Antheridial sacs are formed abundantly upon the prothallia. 
They are found chiefly along the middle, but scattered sacs are 
often seen on either side and may be even marginal. 
Figure twenty-six represents an anaphase stage in the first 
division of the central cell of an antheridial sac. It has the 
usual shape of such central cells; the basal side is conical; the 
distal side nearly hemispherical. The cytoplasm is dense, con¬ 
taining few vacuoles. The karyokinetic figure occupies a rela¬ 
tively small part of the central portion of the cell. The spindle 
is broad-poled. The chromosomes are long, slender rods. 
About one-third of the total number in each of the two groups 
is repreesnted in the drawing. There are several darker stain¬ 
ing granules scattered in the cytoplasm whose nature has not 
been determined, but neither in this nor in later divisions in 
the antheridial sac up to the sixteen celled stage has anything 
been seen which could be called a centrosome or blepharoplast. 
The last division in the sac was not found. 
A resting cell of the eight-celled stage in the antheridial sac 
is shown in figure twenty-seven. It is drawn on a much larger 
scale (2700 diameters) than figure twenty-six (1950 diame¬ 
ters). The cell drawn in figure twenty-seven resembles closely 
the corresponding stage in Adiantum. Cells at this period are 
commonly but not always long and narrow. The convex sur¬ 
face of the cell drawn, was applied closely to the inside of the 
wall of the antheridial sac. The other sides were flattened, 
fitting against the neighboring cells in the sac. The cytoplasm 
is loose, containing large vacuoles. The nucleus is elongated, 
following roughly the contour of the cell. The chromatin is in 
a very finely divided condition and the reticulum consists partly 
of granules of various shapes and partly of fine branching 
threads. There are several large conspicuous spherical nu- 
cleoles, three of which are shown in the drawing. 
In figure twenty-eight, which represents an antherid at the 
time of the beginning of the elongation of the blepharoplast, the 
conditions are very different. The cell (drawn to the same scale 
as figure twenty-seven) is much smaller. 'No nucleoles are 
