17th February, 1955.
Dear Dr. Siegel,
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 material.
Yours sincerely,
Rosalind Franklin.