The iudividuality of the chromosomes and their serial arrangement, etc. 119 
As thc fibres continue to push iiito the nuclear cavity the loops of the 
spirem become flattened out in the plane of the equatorial plate. A 
lateral view of tliis stage is shown in figure 13. This stage is a very fre- 
quent one in my preptu'ations. Figure 14 is a polar view of the series as 
it enters the equatorial plate and it shows that the serial order of ar- 
rangement of the chromosomes is still preserved. At this stage the spirem 
is irregularly looped and its parts may be crossed. Later as the chromo- 
somes conie to lie in the plane of the equatorial plate, the entire spkem 
lies in one plane without any apparent Crossing of its parts. ’VVhen the 
equatorial plate is completely formed the chromosomes are rather closely 
crowded together into an almost solid plate in which they are so evenly 
spaced that the serial arrangement is not clearly in evidence. At this 
time the nucleole is usually absent, but in some cases it can be seeii at 
one side of the plate, but much reduced in size (fig. 13). Düring the 
late prophases the nucleole gradually decreases in size as if it were being 
dissolved. 
It is to be noted that no split or line indicating the location of the 
future plane of cleavage is to be seen in the chromosomes at any time 
in the prophases. The mother chromosomes lie in the equatorial plate 
as compact ellipsoidal masses forming a rather solid plate. The whole 
number of mother chromosomes divides in the equatorial plate almost 
simultaneously. In a lateral view of an early anaphase two rather even 
ranks of daughter chromosomes are to be seen dose together in the con- 
dition shown in figme 15. The daughter chromosomes are elhpsoidal or 
spherical in shape and when first formed they are about half the size 
of a mother chromosome. 
A polar view of the group of daughter chromosomes during early 
anaphase shows that the serial arrangement is probably still maintained 
although the chromosomes are too dose together to allow one to trace 
wth absolute certainty a continuous series for any considerable distance. 
We may consider that in effect the discrete spirem that existed in the 
equatorial plate has beeil spht into two daughter spirems, and that the 
chromosomes divide uniformly and simultaneously without losing their 
serial order. The daughter chromosomes thus maintain the same serial 
Position with reference to each other which was occupied by the mother 
chromosomes. As the poles are reached the daughter chromosomes are 
usually closely packed together. Especially is this the case when a well 
developed System of polar rays extends from the polar ends of the spindle 
(fig. 16). In such cases the individual chromosomes are densely packed 
together. When there are few astral rays the chromosomes are more 
