Volume 44, Issue 1
July 1956, pages 1-55
pp 1-2 July 1956
pp 3-29 July 1956
pp 30-37 July 1956
pp 38-46 July 1956
Based on F2 data and checked in the F3 generation for the Thatcher × Frontana cross, the seedling reaction to race 126 of leaf rust was explainable on the basis of an interaction of a dominant factor for resistance from Frontana with a dominant factor for susceptibility from Thatcher, the latter being epistatic to the Frontana factor, the resulting ratio in the F2 being 13 susceptible: 3 resistant.
Resistance to race 126 of leaf rust at the six-leaf stage appeared to be governed by a single factor pair with incomplete dominance in the Thatcher × Frontana cross.
Maximum likelihood formulæ were derived to measure linkage between six-leaf stage reaction to race 126 of leaf rust, segregating 3 resistant: 1 susceptible and seedling reaction to the same race, segregating 13 susceptible: 3 resistant. The formula for an assumed linkage between the factor for adult plant resistance R2 and the R factor conditioning resistance at the seedling stage gave a recombination of 8·25±4·8 per cent. The formula for an assumed linkage between the factor for adult plant resistance R2 and the S factor epistatic to the R factor for resistance at the seedling stage gave a recombination of 22·7±6·4 per cent. Linkage is indicated and all the three factors R, R2 and S are linked, but the linkage between R and S appears to be loose amounting to independent assortment.
pp 47-55 July 1956
1. The nucleus could be observed in the living cells from a 96–120-hr. culture of a strain ofSaccharomyces cerevisiœ.
2. It could be followed up during the processes of fixation, hydrolysis, staining and dehydration. In its staining reactions it is identical with the nucleus described by the early investigators.
3. Under the phase contrast microscope there is no uniformity in the architecture of the resting nucleus in living cells. It may be a homogeneous body or may contain denser areas or formed structures inside.