MIlANHI

29,1952 ) %
roi;t3,s%7r  I,rlfE 1

                j-it?I-l$E 4 e f- -AK ' y1 dfidrn!m~ bflE t 21Lr3 .`(:I 17ofi9m

                               -979?rtH 2' rioi
      Your letter*';of F'&.#has" been received; it
ci>ossed over with mine. As`"g%&ns a joint paper,1 shall
send YOU a draft giving details of all my experiments related
to the problem as soon as I come back from Britain - the 11th
or 12th Of Karch. Unfortunately 1 am leaving tonight and cannot
do it before. 1 am sorry to leave the burden of wr'ting the
paper entirely to you, but the excuse-of the knowledge of the
language,is, I hope, a sufficient onei I shall see Iiayes in
London; he has written to me that the expekiment he planned
in his letter,which you know,has in fact confirmed infection
b$? F+ . 1 should suggest quoting his independent result,and
should ask him more details about it,=
        1 have not yer repeated the experiment with
purified IjWA-ase :  none available here.  I hope to get some in
Britain. 1~~1~0 hope YOU have a chance. of confirming this point.
I shall of course be repeating this experiment as soon as I come
back.

         I hope Hfr has reached you in. good health. I have
been unable to obtain transformation of F- cells mith Hfr,but
have tried only once. Another interesting fact is that some of
the F- strains brn which F+ hss been transduced seem to give a
high frequency of recombination (due out Of six tested),while
the others give a low frequency ! Perhaps we are dealing with a
mixture of transducing principles,or recombinations of them.
It, is not yet clear to me Mat Hfr can mean,if it does not - as
it does not seem to-follow your hy:>othesis of/bp%%f% F+ donor.
However I have a sort of fe;$ling that some explanation can be
found.

      YOU will not,1 hope,be too/%@ised of a sentence
which I wrote to Hayes in the letter of wh ch I sent you a copy.
As a matter of fact,jEkH I still believe that recombination and
infe6dsion are entirely separate things ,as is fairly obvious
from all experiments sofar,but I have been astonished by the Pos-
sibility of obtaining genetic infection with such a high yield
in the absence of trans?   gArJnciplf3; ,is,$ f  filtrates - or
any ~*timr sort of lysate   ave h.3. som8yposi t i$e results,but
rather difficult to reproduce.  After all,  besides the fact that
recombination involves a co-related change in a numbe? of markers
which is Of course &he fundamental difference, and that th-e
exchnngc? is reciprocal,  the other differencss bet;veen recombina-


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tion andFrnfection remain<"' th&'&quency with which e&&her pheno-
menon occurs,and peprbably T)NA-ase sensitivi~~~.~~slt;,~3ch!..