December 13, 1957
Dear Ruth:
I'm not sure I remember what you wrote about - perhaps it was this. A matroclinous type of inheritance does not rule out chromosomal determination. Your zygote just might not get a certain chromosome from one parent, and double up on the other one, something like "sex ratio" in Drosophila, though here the mt chromosome does not control its own behavior, but that of another one. Sciara would be another precedent for selective elimination of chromosomes.
I don't know how you can rule out this class of hypotheses - an anomalous mechanics for a chromosome can probably be devised to match any plasmid.
Yours sincerely,
Joshua Lederberg