349 
the Embryo-sac Mother-cell of Lilium . 
suggested that this difference in form presented by the chromatin might be 
due in part to the effect of the osmic acid in the fixing fluid, or to the 
action of the fluid as a whole. If the fluid penetrated readily and quickly, 
a coagulation in finer granules would result, whilst a slower penetration, or 
one such that the strength of the osmic acid is made weaker by virtue of its 
having to pass through a thicker layer of tissue, would lead to the coarser 
lumps of the chromatin. The results obtained by the method of preparing 
the ovaries for this study seem to favour this view. The writer does not 
advance this explanation as a theory to explain all similar phenomena, but 
merely offers it as a suggestion which seems to be in harmony with certain 
facts. Nor should it be inferred that he regards synapsis as an artifact, 
when it is suggested that the reagents may be responsible for the greater 
compactness of the synaptic ball, for it is generally true that the reagents 
used in this and similar indirect methods of study cause a certain amount of 
contraction of the material, although this may be very slight. 
In both micro- and megaspore mother-cells, there is a single spirem 
developed which passes into synapsis, assuming, of course, that a complete 
spirem is formed prior to synapsis. This seems nowhere else so beautifully 
shown as in the megaspore mother-cell of Lilium . There is, therefore, no 
pairing or fusion of spirems in synapsis. The hollow spirem appearing 
after synapsis is seen to be double, and all facts point to the conclusion that 
this is due to a real longitudinal fission — a fission as real as in the ordinary, 
or ‘ allotypic 5 , mitosis. Occasionally the halves may separate or diverge for 
considerable lengths, but this divergence or separation of the halves is only 
temporary, the segments coming together and uniting or adhering closely 
before complete cross-segmentation of the chromatin cord. It is suggested 
that this divergence of the halves of the longitudinally split cord may be 
due in part to the action of the reagents, but this statement is not made 
with positiveness. 
The somatic chromosomes (assuming the individuality of the chromo- 
somes) are arranged end to end in the spirem, and two members of each biva- 
lent chromosome, whenever they lie side by side in their final position, are 
brought to that position by a looping or other manner of approximation. 
A very striking proof of the end-to-end arrangement of the somatic 
chromosomes in the spirem is seen in Oenothera , according to the results of 
Gates (’ 08 ). Here, in nuclei uncut by the knife, the majority of chromo- 
somes (l. c., Figs. 26, 27, and 28) can be seen adhering end to end in the 
segmenting spirem. In Oenothera there is likewise no union of spirems 
side by side in synapsis, as only a single thread is present prior to synapsis. 
Of the species studied by me, Trade scantia more closely resembles 
Oenothera. In Peperomia the recent investigations of Brown (’ 08 ) have 
shown that a single spirem passes into synapsis, and that the chromosomes 
are arranged end to end in the spirem, the members of the bivalents being 
