Birkbeok College Crystallography Laboratory,

21/22 Torrington Sqpare,

London, W.c.1.

Trre A, Siegetl,
Dept. of Botany,
University of California,
405 Hilgard Avenue,
Lor Angeles 24
CALIFORNIA, U.8 .A,

17th February, 1955.

Dear Dr, Siegel,

I have just recently obtained some really good X-ray

photographs from the TMV *ieh you sent me last November.
show some small bu$ anterestin

They

points of difference from my

original photograph8 Of Pirie f 8 material.

I have unfortunately mislaid your letter in which

you told me which strain it was you had sent me, and should be
grateful if you would give me this information once again.

       It is iEpossible to say, at present, whether the
difference which X observe between your material and pirids its
due to the difference in strain or to the difference ifn the method
of preparation.  Pirie purifies his material by incubation with
trypsin, which may well remove something from the surface of the
particle, Z think it would, therefore, be of interest to compare
the material you sent me with a different strain prepared by the
same method, So if you are able to spare me, some time, some
of one of your other strains I should be extremely grateful.

       I have so far only taken photographs of orientated
gel preparations of your material,  1 intend also to try to get
a measurement of the particle diameter in a dry preparation, for
comparison with the 1526 obtained by Bernal and Fankuchen for
Piriels material.

Yours sincerely,

Rosalind Franklin.