32 Wisconsin Academy of Sciences, Arts , and Letters. 
tened against each other. The two nearly spherical nuclear 
cavities are connected by a rather narrow region of fusion. In 
each of the two nuclear cavities there is a dense mass of chro¬ 
matin threads, and a dense series of similar threads runs from 
one mass to the other. The two synaptic masses of chromatin 
are equal in size (the plane of the drawing passes tangentially 
through the left hand mass) and resemble very closely the syn¬ 
aptic masses in the other cells in the sporange. Double cells 
with a somewhat broader opening between them have been seen 
in even later stages, containing normal heterotypic chromo¬ 
somes. 
After synapsis, which apparently lasts a considerable time, 
the chromatin again spreands out through the large nuclear 
cavity. A stage in this loosening of the knot is seen in figure 
fifty-four. A rather thick section through the cell is repre¬ 
sented, and shows the enormous length of thread that is present 
at this time. Ho attempt was made to follow the thread 
through its intricate windings. The thread is everywhere uni¬ 
form in diameter and can nowhere be seen to be double. Here, 
as in synapsis, the layer of cytoplasm on the side of the cell 
nearest the chromatin knot is very thin. 
As the spirem spreads through the nuclear cavity, the nucleus 
regains its central position in the cell. In figure fifty-five we 
have the large nucleus centrally placed. The spirem, which is 
now nearly uniformly distributed, consists of long, fine threads 
that wind in and out irregularly through the large nuclear cavity 
and are everywhere double. Sometimes the two strands lie 
parallel, sometimes they are twisted upon each other, but there 
are always two. The course of one of these double strands can 
often be traced, irregularly bending and looping, half way 
across the nucleus. 
Segmentation now occurs and the chromosomes are at first 
long and slender but soon shorten and thicken. In the stage 
represented in figure fifty-six, the length of a chromosome ex¬ 
ceeds the diameter of the nucleus. The chromosome is easily 
seen to be double. Later, as the chromosomes shorten they ap¬ 
pear as pairs of thick rods uniformly distributed through the 
nuclear cavity. Sixty-nine chromosomes were counted in a 
