MOTTIER AND NOTHNAGEL: CHROMOSOMES OF ALLIUM 563 
SUMMARY 
The resting nucleus prior to synapsis consists of a reticulum 
of linin and chromatin granules and of one or more nucleoli. 
The ‘“‘Chromatinknoten”’ of Bonnevie are not present. 
Before synapsis there is, as in Lilium, a tendency to form a 
delicate continuous thread or spirem. There is no union of two 
spirems in synapsis. 
Synapsis is a real contraction of the nuclear net and not a 
growing away of the nuclear membrane from the nuclear network 
as claimed by Lawson. 
The spirem is a direct transformation from the nuclear net. 
The hollow spirem is a thick chromatin cord in which a longi- 
tudinal split is only occasionally seen and only in parts of the 
same. This split whenever present always closes up completely 
before the cross segmentation. 
The rearrangement of the spirem takes place which is referable 
to the second contraction described for the lilies and other plants. 
This results in an entanglement of loops and parallel parts of the 
spirem which twist upon each other. During this rearrangement 
the transverse segmentation of the spirem occurs. 
Each bivalent chromosome is formed by an approximation, 
usually side by side, of different lengths of the spirem, which may 
have appeared as loops or otherwise. Each bivalent is, therefore, 
to be regarded as two somatic chromosomes that were previously 
arranged end to end in the spirem. The approximation of two 
somatic chromosomes, side by side, or otherwise, or their adherence 
end to end to form bivalents, is not known as synapsis in botanical 
literature, nor is it properly called a conjugation. 
The prevalent form of bivalent upon the mature spindle is 
the large ring, although other forms exist. 
The daughter segments split longitudinally during shisha: 
This fission may be looked upon as a preparation for the second, 
or homotypic, mitosis. 
In the construction of the daughter nuclei, the chromatin 
does not pass into a finely divided state. The chromatin segments 
elongate greatly, becoming wavy or zigzag, and form an inter- 
rupted spirem by the union of a number of the free ends. This 
spirem is disposed in the form of a wreath or crown open at both 
