March 1, 1931
Dear Charlie,
Our plants have been very late. I have just started looking at the c-sh-wx chromosome. From what I have seen it seems clear that the knobbed chromosome, the 2nd smallest, is the c-sh-wx chromosome. In the material I have there are 3 size differences of the knob. Very large, small, and smaller or about [diagram] and no knob. In one plant the synapsis showed 2 of the type 3 and one of type 2. I am going to cross this plant with type 1. This points toward the fact (which will be verified in a few weeks) that the c-sh-wx genes are arranged [diagram]. I hope Beadle will be able to find on which side of the spindle fiber region the different genes are.
Harriet tells me that Beadle has been finding many knobs in teosinte: I saw many in his material last spring -- 2 on a chromosome, etc. In fact, I believe the reason for the appearance of longer chromosomes in teosinte as compared with maize may be due to the added amount the knobs give to the metaphase chromosome. I feel convinced that such is the case with the satellite chromosome.
Will let you know whether the 3rd smallest (number 8) comes thru in my other stock. Do you want me to send you some stock? I will let you know how it comes in a few weeks.
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Trisomic synapsis is interesting. In the early stages it looks as if Newton and Darlington were right. In many cases it was obvious that only 2 chromosomes synapse at any one place. Change of partner looks like -- [diagram] I have seen some nice cases. I don't know whether 3 chromosomes lie side-by-side thru accident or whether it amounts to 3 chrs. synapsing. I think it is accidental, however and that synapsis is 2-by-2. In some cases one of the 3 chromosomes was entirely free in the early prophase. A univalent thru out probably. If synapsis is by chance (2-by-2) this might occur.
So much for the present dope -- I have been at it 2 days only, so much is inchoate. Will let you know any interesting developments,
My regards to the crowd --
Sincerely
Barb.