Osborn Botanical Laboratory, Yale University, May 16, 1947.

Dear Mather-

Under separate cover, I safll shortly send you a manuscript
entitled "Problems in the Genetics of Microorganisms". This is
really only a preliminary draft, but it does indicate the scope
and point of view of the review whose writing I had mentioned
previously. I had planned a more extensive paper, but while I
was writing, I was fortunate to see a manuscript of a review bE
Iuria which has just been published in Bacteriological Reviews.
Turia's paper is quite a comptent job,
which I should not like to duplicate, but I think there may be
room for the more speculative, and more professionally genetic

get e of approach which my tproblems" represents. I am sending
“Linthis(dratt Iniits presentstate, for the benefit-of-any suggestions
which you may care to make; “amd/to learn, if you would’'be so kind
as to transmit this letter andthe script, to Dr. Darlington,

.  swheé'ther it would be regarded as’ suitable in its general cast, for

“. HEREDITY. If it is, I should LiKe. to learn what form of List of

: aReferences would be preferred.” &-:

‘al bi Bet ea

~! Phank- you for plawing me on the John Innes mailing list; the

~{
mi teh

suse of selectional techniques in‘genetics of higher plants, as
represented by the report of mutations at self-sterility loci
“was particularly interesting; most of the mutational characters

“of microorganisms can be found by a‘similar type of genetic

 

“"siewe."2 x oR ek -

. Pa e ee Sa

4  @here is. little further, to’ be, added concerning the genetic

a map of E. coli; a few drug-resistance. characters have been ten-
tatively located.on ‘the:same single linkage group, and the com-
parison of the segregation.‘of alleles: in alternated crosses,

as.wag done for the.y*-v® alternatives has been extended to

Tac¥t Lae- Gnd fo-01aF-cla®  chlproactpic acid resistance) with

/ correspondingly satisfactory results}: no cmssover-suppressors

‘nave been! detected still (with mystard or X-ray) so I am trying

“now to develop polyploids,: using the suppression of new recessive

w

. mutations as a means. of detecting them after various treatments.

fhe results so far are highly tencouraging, but not conclusive;
“putthis-ds'talked about in the review.

 

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2 ae & rs wn .
“Ee Havesyou given ‘any further.*thought to the problem of esti-
oh, ating: the ‘absolute aistances} from the multiple crossover frequenc)
*""Sre"four strand system? Or rather, have I made the problem
” elear?I gari}t think ‘of ahyone’else whom I can bother to worry
«°° Bhout-that Kind of case. There 4S still (after another experi-
mental attempt) no evidence thét: there is more than one viable
progige, ofg8 27 gours but, the sét-up is still not pptimal for
5 ee

“the Sctionof others, “a. --.--.—— — eee hcinssclis chien ee

 
  
 

 

Turia is now talking aboutva fantastic story in phages:
two phage particles each of which pears#UV-induced. "lethal mutat
tions! can interchange in a bacterial cell and give rise to non-
lethal products; by using phages carrying many lethals and

claculating the frequency of coincidence of lethal mutations in
- sthe “two phages, the tota}.number of -genes is estimated, and
cre oub te range from.35-65 an: arious coli. phages.

2 2: tea: