The Distribution of Chromosome 9 in Triploid Allium Triquetrum

Abstract

Of increasing interest to cytologists today is the question of random or non-random distribution of chromosomes at metaphase. Cytologists are becoming more aware of the achievement of some orderly spatial arrangement of the chromosome complement by metaphase. This orderliness, or non-randomness may result from several different causes, that of interest in this paper being the tendency for homologous chromosomes to lie closer together than would be expected if the chromosomes in the complement were randomly dispersed, i.e. the phenomenon of somatic association. Considerable evidence has been documented to support this idea in various groups of plants and animals, e.g. Schneiderman & Smith 1962 in human peripheral blood and skin cells, Ferguson-Smith & Handmaker 1961 in female human peripheral blood cells, Barton & David 1962 and Galperin 1968 in normal human cells, Rickards (pers.comm.) in Allium triquetrum and Therman 1951 in Ornithogalum (Liliaceae). However, most of this evidence has referred to diploid organisms, little attention having been paid to triploid form. This paper therefore examines the distribution of members of chromosome 9 (Rickards) of triploid Allium triquetrum, to determine whether these chromosomes are randomly or non-randomly distributed. Chromosome 9 members are known to exhibit somatic association in the diploid (Rickards pers.comm.)