556 MOor;rTriER AND NOTHNAGEL: CHROMOSOMES OF ALLIUM 
structure there takes place (I. c. 197) a pairwise conjugation of the 
chromosomes, which finds its culmination in synapsis. This 
conjugation is accomplished by the lateral fusion in pairs of the 
threads radiating from the chromatin knots (I. c. fig. 20). Soon 
after this (I. c. 198) such nuclei become more irregular, for, in 
addition to the chromatin knots or lumps, there appear other 
dense accumulations of chromatin, so that, as a result, the original 
radial arrangement of the threads is no longer recognizable (I. c. 
fig. 21). 
In the light of their own preparations as compared with 
Bonnevie’s figs. 18-21, the writers are convinced that Bonnevie 
is describing the appearance of very poorly fixed and poorly 
stained nuclei. That Bonnevie has failed to distinguishabetween 
good and bad fixation is clear to the writers from the following 
(Il. c. 198): “Ja, das Zusammenlaufen = Chromatinsubstanz 
kann soweit gehen, dass alles Chromatin des I iner einzigen, 
optisch schwer analysierbaren Masse zusammengeballt erscheint.”’ 
This is true, but such phenomena do not represent normal steps 
in the mitotic process; they are largely artifacts. It is true, as 
has been pointed out some years ago by one of us (Mottier, ’07, 
fig. 15), that chromatin granules may sometimes form accumula- 
tions either by themselves or grouped about the nucleolus, but 
such phenomena are to be regarded more on the order of chance 
occurrences than as representing significant and regularly appearing 
stages of the nucleus. It is conceivable that such accumulations 
of chromatin granules may be run together or fused by the reagents, 
and it is highly probable that the Chromatinknoten were formed 
in this manner. We do not find these masses of chromatin in 
our preparations. Atany rate the Chromatinknoten of Bonnevie’s 
figs. 18-21 are not to be regarded as of any consequence in the 
normal process of mitosis, as will be seen from what follows. 
THE RESTING NUCLEUS AND SYNAPSIS 
The nucleus of the resting stage in the pollen mother-cells - 
of Allium cernuum Roth presents the well-known net or reticulum 
of linin upon which are distributed with more or less regularity 
the chromatin particles or granules. From one to several nucleoli 
of varying sizes are present. Fic. 1 illustrates the structure of 
