1913] YAMANOUCHI—ZANARDINIA 21 
cell increases as it grows, until it reaches three times its width; 
then the nuclear changes begin. By this time the mother cell 
assumes its characteristic ellipsoidal shape, slightly swollen at 
the top. The nucleus grows with the growth of the cell (fig. 77). 
The nucleus in the resting condition contains delicate chromatin 
fibrils and a nucleolus. Outside the membrane and tightly applied 
to it there are deeply staining globules (fig. 77). As the chromatin 
fibrils inside the nucleus grow in quantity, the number and amount 
of the deeply staining globules diminish - 
(fig. 78). Finally there appear chromatin 
threads stronger and more continuous than 
before, and the globules lying outside the 
membrane disappear completely. It is pos- 
sible that these globules consist of material 
closely allied to chromatin, and that they 
pass into the nucleus, thus contributing to 
the formation of chromosomes (fig. 79). 
The chromatin threads, which are con- 
tinuous for a considerable distance, run 
irregularly through the cavity and become 
more uniform in thickness (fig. 80). They 
gradually become arranged near the mem- 
brane, their parts running parallel by re- 
peated bending (fig. 81), and finally there 
are established a number of loops of differ- 
ent sizes centering at one part of the Fic. 18.—Sporelings: a, 
membrane (fig. 82). These loops shorten from a fertilized gamete 30 
and thicken (figs. 83-85). The loops now 42YS after fertilization; , 
: rom a zoospore 25 days 
show double arms lying side by side; each after becoming quiescent. 
arm of the loop is a single structure, its 
origin having been traced from the first indication of a thread 
structure direct from the chromatin fibrils. The transverse section 
of these parallel grouped loops is shown in fig. 86; the cut ends of 
two arms of one loop lie closer than the cut ends of the arms of 
another loop, and the number of the ends is about 88. The 
shortening and thickening of the loops proceed, and then they are 
gradually detached from the main group and form paired chro- 


