Problems of Crossing-Over in Triploid Drosophila, with Criticism on Mather's Inference

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Abstract
K. Mather [see B. A. 8: 17148] expressed the opinion, on purely theoretical grounds, that only 2 of the chromosomes of a triploid can be effectively associated at one level and that the association between the pairing units, instead of being at random with respect to the rest, tends to occur in blocks. For this argument he used the data for the long autosomes of D. melanogaster presented by Redfield. The present author, reexamining Mather''s formulae, concludes that Mather''s method is not so diag-nostic as he supposed. He inclines to the view that, as far as experimental data on Drosophila indicate, the 3 chromosomes of a triploid are all associated, if not always, along their whole length, or else that only two chromosomes are associated at one level and the pairing units behave independently of one another in the auto-somes ; further, that the manner of synapsis and crossing-over in the triploid autosomes is somewhat different from that in the triploid X-chromosomes.