Letter from H. Bentley Glass to Barbara McClintock
A letter with comments on some of McClintock's data on the segregation of heterozygous translocations in maize.
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1940-03-02 (March 2, 1940)
Glass, H. Bentley
Original Repository: American Philosophical Society. Library. Barbara McClintock Papers
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Breakage-Fusion-Bridge: The University of Missouri, 1936-1941
Box Number: 1
Folder Number: 7
March 2, 1940
I am enclosing, after so long a time, your data on the segregation of heterozygous translocations in maize. Burnham, at the
Christmas meetings in Columbus, told me that he was planning to do some further work on this problem, and that you had promised
to send your data to him. I am very glad that someone working in maize is going to continue work on the problem. I am still
very much interested in it myself, but have temporarily laid it aside until I can complete the study of the comparative susceptibilities
to X-ray treatment of the chromosomes in the male and female germ-cells of Drosophila. Perhaps by the latter half of this
year I can get back to it. Your data interested me so much that I was unwilling to return them until my secretary had made
a copy. Afterwards I had to check them for accuracy, and what with an experiment in progress, a pressing editor, and the
flu, it has been impossible to get them off before now.
There are one or two things concerning which I have questions. (1) In 6-10T, how do you know that among the crossovers, the
frequencies of orthoploid and aneuploid 1 gametes are equal? I didn't find the statistical data for this conclusion which
is a very interesting one. (2) In 6-5Ta, what was the pollen sterility? Apparently it was 50% among the non-crossovers.
How did it work out among the crossovers? (3) I am still unable to see why a symmetrical equal-armed cross figure, with the
spindle attachment at the intersection of the cross would logically yield one orthoploid: one aneuploid 1: one aneuploid 2.
I should expect to get the ratio 2: 1: 1, as in the translocations studied in Drosophila by Dobzhansky end Sturtevant. [HANDWRITTEN
NOTE: See top of yellow sheet.]
On the whole, I think your data fit in very well with my hypothetical analysis of the factors controlling segregation. There
remains the question of the influence of the location of spindle attachments in conjunction with crossing over in interstitial
regions where the chiasmata cannot terminalize. I hope to keep in touch with Burnham, and look forward to getting more light
on these points.
Suzanne would send her regards if she knew I were writing. We often think of you, and the pleasant times we had together
in Columbia. For my part I heartily wish I still had the stimulation I got from dropping in to talk things over with you.