C. Arthur Knight was one of many virus researchers that Franklin visited during her 1954 trip to the United States. A colleague
of Wendell Stanley, Robley Williams, and Heinz Fraenkel-Conrat, he sent her samples of cucumber virus and iodinated TMV. In
this letter she reported that she was still having trouble getting the samples to orient well enough to do x-ray diffraction
with them, and concluded that they had dried out too much in transit.
NOTE: Best image that could be obtained; carbon copy with light text.
Number of Image Pages:
1 (60,559 Bytes)
1954-12-22 (December 22, 1954)
Knight, C. A.
[University of California, Berkeley]
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.
Since I last wrote to you, I have made numerous attempts to orientate both the specimens you sent me. I am afraid I am now
convinced that the trouble is due to their having got too dry in transit. They behave, in fact, very like normal TMV which
has been dried and re-wetted.
Straight end-to-end aggregation, such as probably takes place in all solutions, I believe makes subsequent orientation of
the material easier. But it seems that, on drying, there is a more irregular and irreversible aggregation of the particles,
which is shown by the modification of the physical properties on re-wetting. The substance stays in gel for that much greater
dilution, and its birefringence is much lower. The dilute solution seems to show less birefringence of flow.
In confirmation of this explanation of my failure to orientate your specimens, I find that I can get slightly improved orientation
by adding more water and stirring long and vigorously before letting the solution into the capillary tube. But the orientation
is still not comparable with that obtained from normal TMV solutions of material which has not been dried, and therefore still
does not give satisfactory X-ray diagrams.
Both the CV4 and the TMV-I would, I am sure, be very valuable materials for comparison with normal TMV, and if you and Dr
Fraenkel-Conrat ever have any more to to spare I should be extremely grateful if you would let me make another attempt. It
would be best if you would send them in the form of a rather cocentrated solution (e.g. in sealed glass tubes). If the solution
you send is too dilute for direct use, I should have no difficulty in concentrating it to the required consistency.
TMV seems to be capable of preservation indefinitely in the form of concentrated solution. Is this also true of CV4?