Letter from Barbara McClintock to Charles R. Burnham
This letter to Burnham related some of the findings that possibly informed McClintock's 1930 article in "Proceedings
of the National Academy of Sciences" on semisterility in maize. Contains data and illustrations.
Item is handwritten. Item is a photocopy.
Number of Image Pages:
4 (196,898 Bytes)
1930-04-07 (April 7, 1930)
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
A Cytological Demonstration of the Location of an Interchange Between Two Non-Homologous Chromosomes of Zea Mays (1930)
Box Number: 3
Folder Number: 5
April 7, 1930
Things have turned up so fast since I wrote you that I am dashing off a line to bring things up to date. I have been working
on [scientific formula, see Lister Hill?]. Among the regular normals diakineses shows: 3 small bivalves [?] r-g, number 2
and a small number 3 with a large terminal granule. It is not much larger than no. 2 without the granule. The spore stages
show a regular number 1 and number 4 but a fairly large number 2 and the chr. with the granule which is number 3. I have enclosed
a rather poor photograph of the spore complement -- 4 smaller chromosomes [diagram] in the sister plants which all D2 diakineses
[END PAGE ONE]
[BEGIN PAGE TWO]
If disjunction takes place half the time side-by-side and half opposite then we should expect 2 types of fertile spores and
4 types of sterile spores: [diagram]
If all the spores undergo the first division there should be seen the above 6 types in the proportions given.
I took a late stage, about second div. in spores in fertile spores. At this stage the fertile and sterile grains are clearly
distinguishable. I counted the number of sterile spores with 2 nuclei, 1 nucleus, no nucleus and got 170 2-nucleated; 59 1
nucleated, 18 uncertain, 19 no nuclei. It looks as if among the sterile spores 3 of the combinations can go thru the first
division and one can't. Of course we need more counts.
[END PAGE TWO]
[BEGIN PAGE THREE]
To check this I have looked at the spore division figures and have found the normal chr. complement i.e. short number 3 and
long number 2 as in photo; the interchange fertile gamete, long number 3 and short number 2 (which is possibly shorter than
number 1) The sterile combination of two number 3s, a long and short and no number 2; the sterile combination of two number
2s, long and short and no number 3; possibly the long number 3 and long number 2. The other combination -- short number 3
and short number 2 I haven't found as yet but really haven't looked enough.
From this it looks as if number 3 has received more than it has given in the interchange.
Among the 2 nucleated sterile spores some have a few large starch grains and some have none -- there may be a universal difference
i.e. 1/4 of the spores with grains etc, which might be related to a certain combination. [diagram]
[END PAGE THREE]
[BEGIN PAGE FOUR]
So much for the recent dope. I have much to do yet but want you to keep up with all that is going on.