INSTITUTE OF ANIMAL GENETICS - KING’S BUILDINGS - WEST MAINS ROAD - EDINBURGH 9

Department of Animal Genetics, Edinburgh University and A.B.G.R.O., Genetics Laboratory, Agricultural Research Council. Tel. : Edinburgh 44467/8

Professor C. H. Waddington, Sc.D., F.R.S.

Toc /1r/P. R,

Dr. J, Lederberg,

Department of Genetics,

University of Wisconsin College of Agriculture,

hiadison 6,

Wisconsin,

U.S. A, 4th Octover, 1950,

Dear Dr, Lederberg,

Very inany thancs for your kind letter of 22nd September
which has just arrived, I have not yet digested the enclosures
and will reserve comment until a later date, but I am sure they will
prove interesting,

I have now been joined in the reco .bination-fraction/
mapedistance wor: by a mathematical colieasue, Alan Robertson,
Our line of a proach is an attempt to synthesise (i) A distribution
of chiasmata in a bivalent arm, assuming soue c. ias.a-interference
function such as that proposed oy Owen (Proc. soy. Soc., 1949)
put acvlied to the formation of chiasmata in the four-strand
stage; (ii) A ecnromatid-interference function walch has a maximum
wnen the two cniasmata are aijacent, and falls away ex:onentially
as chiasma seoaration increases, Chiasina /Panetien is sti.l h wot
Supcosed to be a chain of events starting fro: the eentromere,

We a.creclate, of course, that this sodel may not
necessarily bear a very close -eseuvience to biological fact;
but feel thet it is provably on the right lines an& worth foilowing
up to see its impiications,

Very many thanks for your xindness,

Yours sincerely,

‘a

( I. U. verter, )

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