The causal sequence of meiosis
• . i . • pro6eeds"., and where crossing-over takes place. These prime wriables ..at6 ghe.eontaet-point, the th~e-lhnit of pairing and. the torsion in paired regions. Their action has been inferred from the comparison of pairing in ~dated forms witt{ variabie pairmg frequencies and ohiasma distribution ; from ~he pa.h-ing in hybrids, mutants and po]yploids; and h'om the ~ifieiaI !n}errnption of normal pairing. Suc]a comparisons have to be m~de ~vifla even ~ea te r accuracy and detgii if gee theory of meiotic p~mng.as to be ~ested and consolidated. The time has now arrived for an exac$ definitio~ of the individual aoti.ons and of the interactions of the t~{'egva.riables and of {Heir effect onohiasma formatim.~. k it}~iJ.y of pagfing variM;ion rest~Ith~g from genetic aad :from en~dr0nmental Souzces, i o an interspeeitie eo.mparison wibh varied environmental eoi~Ntigns,i.forms ~ahe most promising approach. ~,r,gt~igcvria., which h.a,s proved such Useful material in the discovery of ~he ele.me~lts o:[ mitosis and . . . . meiosis, is eminent.]y st~ita, ble :for further ana.].gsis} :[or the following rea.soJ.is:
Karyomorphometric analysis of Fritillaria montana group in Greece
Abstract Fritillaria Linnaeus, 1753 (Liliaceae) is a genus of geophytes, represented in Greece by 29 taxa. Most of the Greek species are endemic to the country and/or threatened. Although their classical cytotaxonomic studies have already been presented, no karyomorphometric analysis has ever been given. In the present study, the cytological results of Fritillaria montana Hoppe ex W.D.J. Koch, 1832 group, which includes Fritillaria epirotica Turrill ex Rix, 1975 and Fritillaria montana are statistically evaluated for the first time. Further indices about interchromosomal and intrachromosomal asymmetry are given. A new population of Fritillaria epirotica is also investigated, while for Fritillaria montana, a diploid individual was found in a known as triploid population. Paired t-tests and PCoA analysis have been applied to compare the two species.
Meiosis in Agapanthus and Kniphofia
The present study was undertaken to find out the special charac teristics of differential condensation of the chromosomes in the prophase of meiosis. It was made on preparations lent me by Dr. Belling, and in part already reported on by him. The preparations were smears fixed in Navashin's fluid and stained in iron-brazilin by Belling's method. This stain is similar in general properties to haematoxylin, although it gives better results with suitable stages, especially with the pachytene stage of meiosis where the whole complement can be readily traced throughout its length. At metaphase the results are less satis factory, because, like haematoxylin, the stain is too dense as a rule to allow of a complete study of the essential side views, such as is possible with gentian violet staining. The drawings were made at a magnification of 3000, with a 100 fluorite objective of Zeiss, a 20 eyepiece, and the aplanatic condenser of Bausch and Lomb used with water immersion and with a special cor recting lens so as to give a cone of 1.3 aperture; they were reduced to 9/10 in reproduction.