Letter from Barbara McClintock to Oliver E. Nelson, Jr.
In this reply to Nelson, McClintock briefly described a plant that shared many of the same characteristics of the corn he
had sent to her.
Number of Image Pages:
2 (152,131 Bytes)
1970-05-29 (May 29, 1970)
Nelson, Oliver E. Jr
Original Repository: American Philosophical Society. Library. Barbara McClintock Papers
Reproduced with permission of the Barbara McClintock Papers, American Philosophical Society.
Medical Subject Headings (MeSH):
Searching for the Origins of Maize in South America, 1957-1981
Letter from Oliver E. Nelson, Jr. to Barbara McClintock (May 13, 1970)
Box Number: 1
Folder Number: 7
May 29, 1970
The ear you sent to me several days ago is being returned to you air mall, first class. I appreciated the opportunity to
view this ear. It also showed restricted distributions of kernels having only white starch in them, although less rigidly
than on the previously viewed ear. I strongly suspect, nevertheless, that the restriction is real. It appears to be another
example of restrictions of kernel phenotype distributions to special parts of an ear. As I mentioned to you on the phone,
I have noted three instances of restriction in my materials. One of these instances is illustrated (Figure 6) and mentioned
in my 1968 paper in Supplement 1 of Developmental Biology. A reprint of this paper was sent to you. I hunted through my
stocks for a second case to show you. I could find ears from only one plant. Ears from all other plants had been shelled.
This plant, 8087B, produced four fertile ears, two on the main stalk and one each on two tillers. Two views of each of these
four ears appear in the enclosed Polaroid photographs. The white kernels received a deficient chromosome 9 from the ear parent
and the dark kernels received the homologous normal chromosome 9.
Plant 8087B had one normal chromosome 9 with the markers C Sh bz wx and a deficient chromosome 9 lacking all of the distal
part of the short arm including the C locus but not the Sh locus. This deficient chromosome carried the markers Sh, Bz, and
wx-m8. An active Spm was present in plant 8087B. The pollen parent in each cross was homozygous for c, sh, Bz, and wx and
it had no active Spm. Pollinations of all four ears were made on August 12 (8/12, upper right corner on each tag). Several
colored kernels on the ear of tiller-2 appear to have colorless sectors. These are bronze sectors produced by somatic loss
of Bz delivered by the pollen parent. Within the colorless class, a few kernels with a Wx phenotype may be noted as well
as sectors exhibiting the Wx phenotype in other kernels.
From the photographs it is evident that restriction of phenotype distributions has occurred, even though the restrictions
are not completely rigid. With this deficiency, I have noted the exhibited restrictions many times.
I hope by now that your campus is a bit more quiet. A long talk on the phone yesterday with Harry Stinson at Cornell told
me of the situation there. Morale among many of the professors is bad and is getting worse. I fear we are heading towards
the Latin American university system. If so, it is the end of creative activities at such institutions. My concern is personal
as well as general. I don't know where to go.
Many thanks for sending me the ears and the kernels. I enjoyed looking at them.