1st May, 1958.
Dear Dr. Klug,
On getting back from the West Indies a few days ago, I was shocked to learn that Rosalind Franklin had died.  I did not know she had been ill and so was completely surprised, particularly as she always seemed so full of vitality.  She will be sadly missed.
I expected that potato virus X would prove a difficult subject.  Bernal many years ago managed to get some pictures but they were nothing like as good as those of tobacco mosaic virus.  Not only is virus X less stable and its behavior less predictable than tobacco mosaic virus, but it is also much more difficult to orientate.  I don't want the sample of virus back, and it is beyond me to suggest any procedures whereby preparations might be made more suitable for X-ray diffraction studies.  If you or Holmes wish to continue with it, I shall be willing to make some more virus, but I think you probably have problems that are likely to return quicker results.
I am returning the typescript of your paper.  The simplest way to do what the editor wants will be to say that the preparations of the cowpea virus were made as described by Bawden (1958), and refer to a paper which will appear in the next number of the Journal of General Microbiology.  Its title and page reference are "Reversible changes in strains of tobacco mosaic virus from leguminous plants" J.gen.Microbiol. 18, 751-766.
The nucleic acid content of both forms of the cowpea virus is similar to that of normal tobacco mosaic virus.  I suggest that at the bottom of page 6 you might be wise to change the word "constant" to "similar".
Yours sincerely,
F. C. Bawden