Articles written in Journal of Genetics
Volume 31 Issue 1 June 1935 pp 1-19
1. The multivalent configurations in the triploid and tetraploid
2. They vary in frequency from cell to cell, but remain statistically constant at successive stages, as they would be expected to do on this assumption.
3. The configurations (contrary to the opinion of previous authors, but as is expected on analogy with all other cases of chiasma pairing) are constant between diplotene and metaphase.
4. The metaphase chiasma frequency is highest in the diploid and lowest in the triploid. This is attributed to a similar difference in original chiasma frequency rather than to a greater reduction in number in the triploid during terminalisation.
5. The curve of variance is higher in the polyploids than in the diploids, as has previously been found in
6. The formation of trivalents and univalents in the triploid gives rise to irregularities in the second division, and to the formation of restitution nuclei.
7. The formation of quadrivalents in the tetraploid leads to numerical non-disjunction which is reflected in reduced fertility.
Volume 33 Issue 1 August 1936 pp 135-149
The somatic chromosomes of
In both species, and in the hybrid, polar views of metaphase I show about half the bivalents larger than the rest, and this is due to their having chiasmata in both arms. This difference necessarily disappears at anaphase.
Secondary pairing and the formation of an occasional quadrivalent show the parent species to be tetraploid. The hybrid must therefore be regarded as octoploid.
The individuals of
Volume 33 Issue 2 October 1936 pp 237-254
1. The basic haploid chromosome number in the genus
2. Although the diploid species probably reproduce sexually in the wild, the polyploids must be purely clonal since no aneuploids have been found.
3. Two main types of change have affected the chromosome morphology of the genus. Genotypic change of size and regulated structural change altering the position of the centromere have separated the genus into three groups with large, medium and small chromosomes. Random structural change has produced complements with reduplicated fragments (
4. Evidence from external and chromosome morphology, from intersterility and from the time at which meiosis occurs, points to the conclusion that the subgroup
Volume 34 Issue 2 May 1937 pp 339-398
Volume 37 Issue 2 February 1939 pp 303-339
1. The tetraploid tulip species have a lower chiasma frequency at meiosis than the diploids and triploids and fewer changes of partner at pachytene than the latter. Consequently although autotetraploid, they form few quadrivalents and are sexually fertile.
2. The quadrivalents that they form may be classified in two ways:
According to the distribution of chiasmata among the four chromosomes. This shows to which of the ten possible types of quadrivalent they belong. These types depend on the number of changes of partner at pachytene and on the symmetry, half-symmetry or asymmetry of the chiasma distributions per chromosome.
According to the co-orientation of the centromeres at the first metaphase of meiosis, whether convergent, linear or indifferent. The type of co-orientation depends upon the distances apart of the centromeres in the multivalent at the time metaphase begins. Co-orientation fails altogether when the centromeres are further apart than they can be in bivalents. These principles agree with the repulsion theory of orientation.
3. The inter- and intranuclear mean squares show no significant correlation of chiasma frequency in the diploids. A slightly positive correlation in the tetraploids and variable correlation in the triploids is presumably to be attributed to the number of changes of partner their chromosomes undergo and to variable external conditions.
Volume 38 Issue 1-2 July 1939 pp 91-123
Volume 39 Issue 1 November 1939 pp 79-100
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