1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 423 
direction, and also there are no clearly defined centrosphere-like 
structures. 
The spindle of the first mitosis is of very short duration. As 
soon as the chromosomes at the equatorial plate separate into two 
groups, the two spindles of the second mitosis suddenly appear and 
the first spindle can no longer be recognized (fig. 157). It is possible 
that the two poles of the first spindle may move along the mem- 
brane and become poles of the second spindle, but I have no evidence 
to support this suggestion. Whatever the origin of the poles of the 
second mitosis, they are placed in an entirely different position from 
the poles of the first. The second mitosis in the tetraspore mother cell, 
therefore, follows so shortly after the first that there is no period 
between for the organization of two resting nuclei. 
The rapidity with which the second mitosis follows the first may 
prevent the organization of centrosphere-like structures at the poles. 
The axis of the two spindles of the second mitosis lie perpendicular 
to each other (figs. 157, 158), and the two nuclear divisions take 
place simultaneously. At anaphase four groups of chromosomes, 
20 in number, pass to the poles, still included in the membrane of 
original tetraspore mother cell, which persists from the beginning 
(fig. 159). These four groups, of 20 chromosomes each, contain 
all together the 80 granddaughter chromosomes shown in jig. 156. 
When the granddaughter chromosomes reach the four poles of the two 
spindles of the second mitosis, four masses of kinoplasm are present. 
The granddaughter chromosomes after reaching the poles soon begin 
to lose their individual outline, and become connected with one another 
to form a network (jig. 160). The original nuclear cavity contains 
at this stage a very large nucleolus-like body which appears during 
the anaphase of the second mitosis (fig. 159). The history of this 
body is not clear, but it seems to be a new structure, developing dur- 
ing the second mitosis, The four poles now begin to enlarge, while 
the Tegion of the nuclear membrane between them becomes flattened 
(fig. 160); consequently the outline of the original nuclear membrane 
is somewhat tetrahedral at this stage. The transformation of the 
four Stoups of chromosomes into four chromatin nets proceeds until 
4 chromatin reticulum occupies each of the four lobes of the original 
Nuclear cavity, 
