Abstract
1. Autotetraploid kale forms from 2 to 5 quadrivalents per cell at diakinesis, with a mean of 4 per nucleus.
2. Only 57% of the second metaphase plates contained 18, the balanced number of chromosomes.
3. The seed fertility of autotetraploid kale is about 35% of that found in the diploid.
4. Secondary associations of chromosomes were examined in the diploid and in the tetraploid.
(a) A high frequency of associations of three chromosomes was found in the diploid. This was, not found by Catcheside (1937). This difference between the two sets of material appears to be a real one and is either genetical or environmental.
(b) At second metaphase in the tetraploid, there are very many different types of plates containing different numbers of associations of 4, 3, and 2 chromosomes. This is to be expected from the fact that if the haploid set can be represented as AA BB CC D E F, then the diploid set in the tetraploid is AAAA BBBB CCCC DD EE FF.
