

Igor] THE LIFE HISTORY OF ERYTHRONIUM Sit 
second is an equation division. Some zoologists have found 
that in certain animals the second is the reduction division. 
Some of the nuclei of Erythronium are of enormous size. 
Those in the walls of the ovule are usually from 15 to 20 in 
diameter, while the large reduction nucleus often measures from 
40 to 50h. In many cases, where the sections were cut 18m 
thick, the spindle was distributed through three sections. In 
such cases the spindle threads not only have their terminals cut 
but they are often more or less distorted. The same is true of 
the nuclei before the spindle is formed. If such a large spindle 
were cut into sections 5 thick it would be distributed through 
nine or ten sections ! 
In the sliced spindles of Erythronium multipolar figures are 
very common. Examples are shown in figs. 31, 32@, 33,34) 
and 35. In fig. 3z one pole is intact and ends in a dark body, 
while the other is cut off. Fig. 32a is a multipolar spindle rep- 
resenting a tangential section. The other part of the spidle is 
little injured and shows well-developed centrosomes at the poles 
(fig. 32). In fig. 34, a strand of spindle threads has been dis- 
placed, so that it projects beyond the limits of the cytoplasm. 
In this material no multipolar spindles were found which were 
not sectioned, and they are therefore not regarded as being the 
result either of normal or diseased conditions, but simply due to 
the method of preparation. Indeed, the nuclei and spindles 
were so large that it was difficult to obtain the chromosomes in 
their normal positions, as they were frequently displaced by the 
knife. 
‘Unfortunately, the stages were not at hand for tracing out 
the origin of the spindle. fig. 28 represents the general appear- 
ance of a section of the nucleus some time before the final 
looping takes place. The nucleus usually has an enlarged or 
expanded appearance, with the spirem lying free in the cavity. 
Fig. 27 shows a large number of false poles produced as the 
result of contraction. In fig. 26 the spirem has looped up into 
the twelve loops, but no sign of a spindle appears either on the 
inside or outside of the nuclear membrane. The loops have not 
