An account of meiosis in various species of the genus
Lilium is presented.
L. pyrenaicum,
L. regale,
L. candidum,
L. umbellatum, and
L. speciosum are diploid (2n=24).
L. Henryi and
L. japonicum have fragments in addition to the diploid complement (2n=24+lf or 24+2ff).
L. tigrinum (three varieties) is triploid (2n=36).
In all the species examined terminalisation of chiasmata is very low and as a result there is very little reduction in the chiasmafrequency from diplotene to metaphase.
Two plants of
L. regale had different chiasma-frequencies and irregular chiasma behaviour,
L. umbellatum had univalents present in some nuclei at meiosis, and
L. candidum showed an irregular chiasmafrequency polygon. These are taken as evidences of hybritity in the plants concerned.
The fragments of
L. Henryi and
L. japonicum are shown to be reduplications and to have a chiasma-frequency proportional to their length. They are further shown to consist of a number of segments homologous with and presumably derived from different chromosomes. The pairing of fragments by interstitial chiasmata provide demonstrations of crossing over at those chiasmata.
L. tigrinum is autotriploid as it has its chromosomes in the form of trivalents and a small number of bivalents and univalents at meiosis.
In all species there was found chromosome or bivalent interlocking, both true and false. The resulting configurations are analysed and shown to favour the chiasmatype theory of chiasma formation.
It is also concluded that the equilibrium position of the chiasmata in uninterlocked bivalents is reached by equalisation of the loops, while in interlocked bivalents the affected loops are larger than adjacent ones provided that neither contains the spindle attachment.
Finally it is shown that the meiotic behaviour of the chromosomes in the various species is in accordance with the view that specific differentiation has been attained by genic or minor structural changes within the chromosomes.
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