Letter from Barbara McClintock to Charles R. Burnham
One of a series of letters to Burnham detailing McClintock's research on c-sh-wx that would result in an article in the
"Proceedings of the National Academy of Sciences" later in 1931. This letter also includes brief personal and professional
comments regarding Creighton and Beadle. McClintock inquired as to Burnham's plans if he was not renewed as a fellow
Item is handwritten. Item is a photocopy.
Number of Image Pages:
6 (350,370 Bytes)
1931-05-12 (May 12, 1931)
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):
Education and Research at Cornell, 1925-1931
The Order of the Genes C, Sh, and Wx in Zea Mays with Reference to a Cytologically Known Point in the Chromosome (1931)
Letter from Barbara McClintock to Charles R. Burnham (March 1, 1931)
Letter from Barbara McClintock to Charles R. Burnham (March 12, 1931)
Letter from Barbara McClintock to Charles R. Burnham (April 11, 1931)
Letter from Barbara McClintock to Charles R. Burnham (June 11, 1931)
Box Number: 3
Folder Number: 4
May 12, 1931
My greenhouse ears are just finishing up. It took a long time for maturity. I had a light for the first month and I suspect
this increased the time of growth before flowering.
I have grown trisomic material of number 5 (6-th smallest) and believe it is the pr-v2 chromosome. I have v2 counts to get
from (x). The (x)s show a 9:1 ratio for pr but the color segregations weren't perfect. The trisomic of number 8 (3rd smallest)
shows clearly that pr is not involved. In this case I had good segregations. I imagine that the other chr. involved in [scientific
formula] is su-Tu or gl1-v5. Rhoades is taking care of number 7 for chocolate pericarp counts. He has the F1 which he is going
to b.e. this summer. I have number 7 (x) for gl1-v5 counts but want to grow for counts this summer so as to get the percent
of trisomes at the same time without making root-tip counts. All my material has been sent off to Missouri. I expect to leave
here in around the first of June.
Concerning the trisome counts I have been wanting to send to you.
[END PAGE ONE]
[BEGIN PAGE TWO]
1 2n plus 1 plants of 270 equals 4 plants examined. 2 were 25-30 percent sterile. 1 was 12-15 percent sterile and 1 8.3 percent
sterile. The one that was 12-15 percent sterile (270(11)) was (x). It gave 11 Purple ShWr: 8 purple Shwx: 1 purple shWx: 25
colorless ShWx: 5 colorless Shwx: 9 colorless shWx: 2 colorless shwx. Some of these kernels were planted in the field last
summer and gave rise to my culture 388. 8 were 2n and 13 were 2n plus 1. 12 of the 2n plus 1 plants were 12-15 percent sterile
(possessed 2n and long interchange chr.); 1 possessed the 3rd smallest chromosome (388 F(1)).
388A(1), D(1) and (2) were from CShWx seeds and were trisomic. Pollen counts were made on 388 A(1) giving 1415 Wx: 69 wx:
347 bad. which is 21.5 Wx: 1 wx or 4.6 percent wx. Sterility 16.3 percent. When this pollen was used on c-sh-wx plants: [diagram]
[END PAGE TWO]
[BEGIN PAGE THREE]
388D(1) plus 1 partial sterile was crossed to c-sh-wx:
388D(2) plus 1 partial sterile was crossed to c-sh-wx.
It is assumed that 2n plus 1 grains did not function.
388A1 [scientific formula] was crossed to your a125(65) plus 69 which was homozygous for the knob and Wx wx I believe. 20
plants were grown. Of these, 9 were 2n and 10 were 2n plus 1. The results were as follows:
[END PAGE THREE]
[BEGIN PAGE FOUR]
Prophase in (3) and (9) showed as diagramed [sic] above. (5) and (7) showed trisome but not knob chromosome.
6 of the trisomes came from n plus long interchange egg. 2 came from n plus number 8 and 2 from n plus number 8 or number
Pollen counts were made on several:
416A(9) equals 665 Wx: 26 wx: 113 bad equals 23.8 Wx: 1 wx or 3.77 percent wx 14 percent sterility. This count is similar
to the parent 388 A(1).
The wx pollen grains are n grains due to x-over or n plus 1 due to cross-over assortment of MI giving 2 number 8 and 1 number
9 with wx.
Distribution at MI depends somewhat on synapses. I have a few counts. Plus 16 A(3) 26 tris: 13 5-M-group: 9 could not tell:
2 10" plus 1: no lagging seen. The tri can be 8-8-I or 9-9 I. The gametes resulting are as follows:
[END PAGE FOUR]
[BEGIN PAGE FIVE]
Gametes from 388A(1) or 416A(9):
Fewer n gametes than n plus 1 is reason why 2n plus I produces more 2n plus one individuals than 2n (reverse of usual trisome
The percent of the 3 types of trisomes should tell something about the distribution. More study is needed. I think I have
included nearly all the remaining information for you to work on. There are some interesting things to do but the value may
not be worth the effort in most cases.
Tell Beadle I have'nt [sic] forgotten to write him but I have a number of things to discuss so have postponed. I shall
see him next year any way. I assume he was reappointed. What have you heard? If you do not get a renewal what are you expecting
[END PAGE FIVE]
[BEGIN PAGE SIX]
Harriet is coming fine with her problem. I am very sorry I am not going to be with her in the work. I think the 2 of us would
do much better than either alone.
Let me know what is new and what you are doing. You can reach me at Waters Hall, c/o L.J. Stadler, University of Missouri,
Columbia, Mo. after June 1.
Too bad about Marion and Beadle. I think it is for the best, tho.
Would you care to write up the order of the genes of the c-sh-wx linkage group with me? I think it ought to be done soon and
should go in the Proc. Nat. Acad-Sci. Your unpublished data is as essential as mine. Let me know what you think