28 ELEMENTS OF PLANT ANATOMY. 
mation, the membrane of the nucleus appears to be removed or 
dissolved, the nucleoli disappear, and the segments arrange 
themselves near the central portion of the nucleus. Next 
appears the so-called spindle, composed of very fine fibers or 
threads, which run through the segments and the entire length 
of the nucleus, converging at the opposite ends, which are called 
poles. The substance of these threads is of a different nature 
from that of the segments, as they either remain uncolored by 
the use of staining agents or take a much lighter color. The 
Fia. 15. 
Division of nucleus and cell of the mother cell of a stoma. — (Aced. to Strasburger.) 
seoments lying in the central portion of the nucleus form what 
is known as the equatorial or nuclear plate. In Fritillaria they 
are in the form of bands or flattened rods; each band now 
divides lengthwise, forming twice the original number. ‘These 
daughter-segments then separate and move toward the poles, 
half to one and half to the other. There they form the founda- 
tion of the two new nuclei. They gradually change their form 
and break up in separate portions, which unite to form at last a 
network similar to that of the original nucleus. Shortly after 
this, a nucleolus appears in each, and a firm membrane sur- 
rounds them and the process of nuclear division is complete. 
