1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 431 
It is interesting to note that the two poles are not in a straight line 
perpendicular to the center of the equatorial plate, but are asym- 
metrical and less than 180° apart. Each of the 4o sporophytic 
chromosomes composing the 20 pairs (bivalent chromosomes) ar- 
ranged in the equatorial plate now splits longitudinally, so that a 
large number of univalent chromosomes results, probably 8o in all, 
although I was unable to count the exact number. 
The group of 80 grand-daughter chromosomes separates into 
two sets, but resting neuclei are not formed, and their further distri- 
bution by the second mitosis begins at once. The axes of the two 
spindles of the second mitosis lie perpendicular to each other, and 
their complex relation to that of the first will be described in the 
final paper. Kinoplasmic masses occupy the poles of the spindles 
in the second mitosis, and each contains a centrosome-like granule. 
Now, each group of 40 chromosomes, following this first mitosis, 
separates into two sets of grand-daughter chromosomes, 20 in each 
set, which are attracted toward the respective poles of the two spindles, 
where the kinoplasmic material becomes more pronounced than be- 
fore. These chromosomes, after reaching the four poles, become 
massed together, lose their individual outlines, and larger and smaller 
granules appear shortly after on linin threads which later become 
contained in the four daughter nulcei. 
It is a remarkable fact that the membrane of the original nucleus 
in the tetraspore mother-cell persists through the two mitoses which 
have just been described. The area included by this membrane 
increases in size with the growth of the cell. The cytoplasm around 
it shows larger alveoli, which become smaller in the vicinity of the 
original nuclear membrane, and at last passes into the kinoplasmic 
fibrils immediately surrounding it. 
At this time constrictions appear simultaneously in the area marked 
by the original nuclear membrane. The kinoplasm intrudes into this 
area in a very interesting manner, which cannot easily be described 
without figures, but results in the organization of the four daughter 
nuclei that are to be contained in the tetraspores. 
The division of the tetraspore mother-cell does not take place 
simultaneously with the events described above. Cleavage furrows 
start along four lines on the periphery of the cell, a little before the 
end of the nuclear division, and prcceed more rapidly after its com- 
