24 BOTANICAL GAZETTE [JULY 
so far as the points here under discussion are concerned, than the 
paper of 1905 (31). The close similarity of the conditions in Galtonia 
and Tradescantia during diakinesis to those in Oenothera suggests 
that they may be found finally to conform to Oenothera in these later 
stages. Whether or not this will be found to be the case, we must 
conclude that in Oenothera the longitudinal fission in the spirem 
(however it originated) closes up, and that after the second contrac- 
tion, or during it, the thick thread segments into the sporophyte 
number of chromosomes. Since this diverges in important respects 
from nearly all the recent accounts of reduction in plants, the con- 
clusion is that reduction probably takes place differently in different 
plants. Whether or not-the results are different from the standpoint 
of a qualitative distribution will not be discussed now. The writer 
believes the above conclusions to be necessary, despite the fact that 
authors have reached different conclusions in regard to the same 
plant, particularly in such cases as Lilium and Podophyllum. 
The next important point which requires discussion and which 
was left undecided in the statement of observations, is in regard to 
whether the double thread observed after synapsis arises from an 
approximation of parallel filaments or through a primary split in the 
thread. It may be well to examine the results which follow from 
either assumption. The writer hopes later to determine more defi- 
nitely this difficult matter. On the first assumption of a lateral 
approximation in synapsis of two spirems representing respectively 
the maternal and paternal chromosomes, we should expect the double 
thread so formed to segment into the reduced number of chromosome 
pairs, in order to conform to the current account in forms in which 
there is a pairing of spirems, for example ALLEN (1), GREGOIRE (16), 
and YAMANOUCHI (33). Instead, however, the spirem segments 
into the unreduced number of bodies. We may still assume that 
each of these bodies consists of maternal and paternal longitudinal 
halves still closely held together and resulting from a previous approxi- 
mation. According to this view the first mitosis would separate 
bodies which were arranged successively on the spirem, while the 
second mitosis would separate the maternal and paternal halves of 
these bodies. The reason for such a result would be that the maternal 
and paternal spirems remained closely fused after pairing, so that 
