During her 1954 visit to the United States, Franklin met or renewed acquaintance with many virus researchers, who were able
to send samples of their virus material and brainstorm with her on her x-ray diffraction findings. Albert Siegel at UCLA was
working with TMV, and in this letter Franklin told him of differences between diffraction photos of his TMV strain and those
provided by N. W. Pirie several years earlier.
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1955-02-17 (February 17, 1955)
University of California, Los Angeles. College of Agriculture
Original Repository: Churchill Archives Centre. The Papers of Rosalind Franklin
Reproduced from the Franklin Collection at the Churchill Archives Centre with the permission of the copyright holder.
I have just recently obtained some really good X-ray photographs from the TMV which you sent me last November. They show
some small but interesting points of difference from my original photographs of Pirie's 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 impossible to say, at present, whether the difference which I observe between your material and Pirie's is due to
the difference in strain or to the difference in the method of preparation. Pirie purifies his material by incubation with
trypsin, which may well remove something from the surface of the particle. I 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. I intend also to try to get a measurement
of the particle diameter in a dry preparation, for comparison with the 152A obtained by Bernal and Fankuchen for Pirie's