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D. Carruthers 
of its former presence. Such an explanation accords better with the 
observed facts than the supposition that the nucleolus has given up its 
substance to the spireme, for there is no apparent augmentation of the 
chromatin content of the nucleus either in amount or in density, accom- 
panying the disappearance of the nucleolus. Eacli chromosome is flat, 
and in the condition depicted in fig. 12 there is a thin part in the middle, 
wliere it finally breaks as the fission is completed (fig. 13). The two 
halves of eaeh chromosome lie side by side at first, and only separate 
as they begin to move up the spindle, when tliey assume the characteristic 
V-form (Figs. 14, 15), the arins of the V being generally directed out- 
wards. 
As the chromosomes pass towards the poles, it frequently happens 
that tliey travel in two or more parts, sometimes quite separate, and 
sometimes connected only by a thread (Figs. 11, 16, 17). In Fig. 16 only 
a part of the nucleus is sliown, and here the segments are very clear; 
the same thing occurs very often, but generally only in one or two chromo- 
somes in each nucleus. A similar arrangement has been recorded for 
Vicia (Fraser and Sxell '11) but it appears to be less common than in 
Hyacinthus. 
The daughter chromosomes collect at the poles, and contract slightly 
becoming rather lumpy in appearance (Fig. 18). They tlien join end to 
end, and split longitudinally at intervals, forming a ragged spireme 
exactly similar in appearance to that formed in the prophase (Fig. 19, 20). 
It is possible that in some cases the lateral joining of the chromosomes 
takes place first, but in the majority of cells there is a definite spireme 
formed first, and afterwards the lateral anastomosis takes place. From 
the ragged spireme stage the reticulum is formed by the pulling out of 
the diamond-shaped areas of the daughter chromosomes, until the net- 
work is reconstructecl in a fashion similar to that recorded for Vicia 
(Fraser and Snell ’ll) (Fig. 21). 
Discussion. 
Pairing of the Chromosomes. 
A paired arrangement of the chromosomes in the somatic divisions 
was noticed first by Strasburger (’05, ’07), and has since been recorded 
by Müller (’10, ’12) for a number of forms, among them Hyacinthus 
orientalis. According to Müller there is a very marked difference in 
the size of the chromosomes and tliey are arranged in pairs throughout 
the division, the pairing being especially noticeable in a polar view of 
the telophase. In the present investigation only one nucleus has been 
