Allen—Spermatogenesis and Apogamy in Ferns. 31 
given in figures forty-nine and fifty. The latter are really en¬ 
tering upon the special presynaptic stage, while in figure fifty- 
one there is no evidence of this. 
Soon after this time, the cells become more uniform in ap¬ 
pearance. The larger ones round out and become spherical, 
lying free from each other in the cavity of the full-grown spore 
sac. The smaller ones in which fusion is complete, grow, be¬ 
coming spherical as they increase in size, and the chromatin 
gradually assumes the appearance found in larger cells. 
Figure fifty-two shows a thin section through a cell during 
this growth. There has been a decided increase in volume 
since the stage shown in figure fifty-one and the angular out¬ 
line has changed to a well rounded form. The cell is nearly 
spherical. The nucleus has also increased somewhat. Nearly 
all of the chromatin is in the form of delicate threads, suggest¬ 
ing the leptoneme spirem. There are still chromatin aggrega¬ 
tions, however, especially in the immediate neighborhood of 
the nucleoles. 
Shortly after this, the chromatin draws off to one side of the 
nucleus forming a dense mass having about one-half the diame¬ 
ter of the nuclear cavity. Spore sacs containing nuclei in syn¬ 
apsis are seen freqeuntly, and usually all the cells in the spore 
sac are in the same stage. These masses are not oriented in 
any particular manner in the sporange. In some of the cells 
the mass is on the side away from the peripheny of the spor¬ 
ange, in others it is on the side nearest it. While the cell is 
in synapsis the layer of cytoplasm is always thinner on the 
side of the cell adjacent to the mass of chromatin than it is 
elsewhere. In cells which have been very lightly stained, the 
structure of the synaptic mass can be made out. No nucleole 
is found at this stage. The chromatin thread of which the mass 
is made is markedly crinkled, and winds irregularly in and 
out. The thread cannot be seen to be double at this time and 
the two strands have probably fused. 
At this stage also there are occasionally cell-fusion stages to 
be found. In one case, a sporange was found containing seven 
large spherical cells in the synaptic stage. The eighth cell 
(figure fifty-three) had the form of two spheres slightly flat- 
