The relation between chiasmata and crossing-over in diploid and triploidDrosophila melanogaster
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Various genetical data on diploid and triploidDrosophila melanogaster are analysed from a cytological point of view.
It is shown that the frequencies of crossing-over in the diploid agree with the cytologically observed frequencies of chiasma formation and persistence in other organisms, so lending support to the partial chiasma-type hypothesis. The various types of interference are discussed.
The behaviour of the chromosomes at pachytene (synapsis) in the triploid is deduced and it is shown to agree with the cytologically observed behaviour of chromosomes in certain plants. It is also shown that non-random disjunction of the chromosomes may occur in a triploid and its genetical consequences are pointed out.
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