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The Barbara McClintock Papers

Letter from Barbara McClintock to Charles R. Burnham pdf (171,831 Bytes) transcript of pdf
Letter from Barbara McClintock to Charles R. Burnham
A brief letter in which McClintock discussed some arrangements for her NRC fellowship at Caltech. Includes some data and hypotheses regarding crossingover.
Item is handwritten. Item is a photocopy.
Number of Image Pages:
3 (171,831 Bytes)
1931-09-25 (September 25, 1931)
McClintock, Barbara
Burnham, Charles R.
Original Repository: University of Minnesota, University Archives. Charles Burnham Papers
Reproduced with permission of the University of Minnesota, University Archives. Charles Burnham Papers
Medical Subject Headings (MeSH):
Zea mays
Crossing Over, Genetic
Box Number: 3
Folder Number: 4
Unique Identifier:
Document Type:
Letters (correspondence)
Physical Condition:
Friday -- Sept. 25. [bracketed in different handwriting, 1931]
Dear Charlie --
Many thanks for your letter telling me about the microscope. Hays has agreed that I should take the research scope and lamp I have with me now to Cal. Tech.
I am sorry that you are low in spirit -- too much sunshine?
I got the dope from Rhoades. In [scientific formula] the break occurred between B and V4 possibly between B and To, anyway. The interchange occurred about here [diagram] probably and about an equal distance in on the U-V2 chromosome (number 5). I had one case of deficiency involving B which would place B toward the end of the long arm equals [diagram] if this means anything B is about [diagram]. L8 is at the end of the short arm from my deficiency stuff so possibly opposite ends are involved in [scientific formula]. Here is Rhoades dope: [diagram] therefore break in L8-b chromosome probably between
D2 and To1. Some F2 data involving [scientific formula] give no crossing over with V4. This is o.k. since B-V4 equals 17 percent crossing over. Break is probably close to V4 locus.
Cultures segregating for [scientific formula] gives 31 plus or minus percent crossing over between U and B.
I had a quick glance at some figures which showed the extent of the interchanges but I couldn't follow back each chr. They were from old slides that Harriet had made. Rhoades is going to finish up the cytology this fall.
Looked up my figures of [scientific formula] and disagree with Cooper on 2 points.
Cooper thinks that arm d belongs to f-u. Whereas I believe from the morph. of the satellite chr. and the 2 small knots that it belongs to the satellite chr. He thinks that arm b is always longer than c whereas I believe they are almost equal, c being slightly longer than b. Anyway, I have seen no chromosome in the corn cultures I have looked at that have a knob close to the insertion region on the short arm which would have to be if the chr. in d and c were the non-interchanged chromosome.
Work is slow -- so much harvesting, counting etc. While home I made a number of photographs which I shall annoy you with when I arrive. I have very little dope except that a is probably out near the long arm end of the a-d-e chromosome with a few more deficiencies -- one in f[ . . . ] chr. [diagram] and one in [ . . . ]-f. [diagram] Examinations are over for a time now until Pasadena. I shall start west in about 2-3 weeks.
See you soon -- regards to all,
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