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MEIOSIS IN GODETIA
327
are distributed t o war ds Ihe poles. A restitution nucleus is very rarely
formed. The anaphase is mostly very irregulär, hut in some cases rather
regulär with as it seems t wo anaphasic plates moving to opposite poles
(Håkansson 1943 a). In diploid G. WhitneyiXG. liottae the tendency
to form a plate is not so strong, in manv p.m.c.’s an equatorial plate
is never formed. A division of I s was not observed, undivided I’s
passing to the poles. In this hybrid restitution liuclei are rather
common. In the triploid hybrids the I’s möre regularlv take their place in
the equatorial plate, and I hey all divide, their chromatids passing to
opposite poles.
Non-division of the I’s at anaphase is probably the rule in such
plants that have a very strong asyndesis. Ivanov (1938) in his review
of the meiosis in haploids emphasizes that only in a few haploids, in
single instances, as a rare exception divisions have been observed. An
example of a regulär division of the I’s was haploid Matthiola incana
but here perhaps a confusion of stages is not improhahle, the division
of restitution nuclei being observed. In haploid Godetia Whitneyi the
seven I’s in many p.m.c.’s form a plate, in some cases the I’s take the
appearance of interkinesis-chromosomes while still lying in the plate
and form a restitution nucleus there. A regulär division of their
centro-meres does not seem to occur, sometimes, however, a mis-division
(H., 1940). In asvndetic plants of Allium amplectens the I’s as a rule
form a strict equatorial plate, hut they cannot divide, a restitution
nucleus is formed from the plate (Levan 1940). Kagawa (1939) found
that in plants of Triticum com pactum X Seeale cereale, treated by
abnormal temperatures, there were only I’s, they formed an equatorial
plate and from this plate a restitution nucleus, which sometimes had
the form of a ring. In this case the behaviour of the I’s was möre
variable, and in certain p.m.c.’s a division of all I’s was noted.
Taking iniö consideration the possibilitv of a confusion of stages
then it seems, that in asvndetic plants the l’s may form a plate but
that a regulär division does not occur. Sure exceptions to this rule are
known, 1) many apomicts, 2) certain Kibes hybrids with rather good
pairing but with a few p.m.c.’s with only I’s forming a plate, these I’s
dividing at anaphase 1 and 2 |Meurman 1928). A few such aberrant
p.m.c.’s have also been observed in Godetia, here the division of the
I’s was not actually observed, though verv probable (H., 1941 b). The
behaviour of the I’s in the diploid hybrids here discussed thus
con-forms to their usual behaviour in asyndetic plants.
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