Meiotic Mitoses of Osmunda. 1 6 1 
through, and consequently may be easily missed. Evidently neither 
Strasburger ( 17 ), Gregoire (10), nor Yamanouchi ( 19 ), were aware of them. 
The first indication of conjunction is to be seen in the drawing together of 
portions of the univalent loops (filaments) or univalent lengths of spireme 
filament in the hollow spireme stage. This is also coupled with the con- 
necting together of the approaching spireme filaments by fine transverse 
strands. The spore mother-cell nuclei of some sporangia may show no 
signs whatever of this early conjunction, whilst in others it is exceedingly 
evident. At the approach of second contraction the conjoining becomes 
more intimate. This phenomenon, again, may be easily overlooked. It is 
not a case of all the portions of spireme filament in a nucleus conjoining 
simultaneously, but of isolated examples of conjunction of lengths and 
segments. During second contraction, the side-to-side conjunction becomes 
so close that, as the bivalent segments come out of the chromatic aggrega- 
tion, they appear to split apart. This disjunction of the bivalents bears so 
close a resemblance to fission, that, if the intermediate conjoining stages had 
been missed, it would naturally be inferred that this is the opening out of 
the fission present in the post-synaptic spireme. Apparently, in some 
instances, univalent segments may achieve the necessary conjunction with- 
out entering second contraction, for it is not uncommon to find fully organ- 
ized bivalent chromosomes lying outside, and independent of, second 
contraction. Moreover, in some species of Primula (4) and Smilacina (14), 
in which the conjunction of univalents (i.e. of filaments) in the post-synaptic 
stages is extraordinarily clear, second contraction is omitted, and close con- 
junction in pairs of the univalent segments (filaments) proceeds freely with- 
in the nucleus ; and when this is accomplished, the univalents separate to 
form the typical bivalent chromosome. 
Although, as a general rule, complete conjunction of univalents (i. e. of 
filaments) appears to require close lateral conjoining of the filament seg- 
ments, yet it seems certain that bivalency may be achieved by a less 
intimate combination, such as a looping over of univalents (filaments), or an 
end-to-end connexion. 
There are no controversial phases from the heterotype diakinesis 
onwards to the end of the homotype division. 
Of recent years Lawson ( 14 ) and Nothnagel ( 16 ) have both published 
valuable evidence in favour of the telosynaptic theory. Lawson has found 
a very clear type of conjunction of univalent segments of spireme in 
Smilacina (14, FI. I, Fig. 16), and, as in Primula , second contraction 
is omitted. He writes that f up to the time of this lateral pairing of the 
spiremes ... I have been unable to recognise any fundamental difference 
from the series of changes which occur in the early stages of an ordinary 
somatic mitosis * (p. 611). 
Nothnagel ( 16 ) very lucidly describes a telosynaptic series of events in 
