AUG 31 1964
August 20, 1964 vEP 11964

Dr. Joshus Lederberg

Space Science Board

800 Welch Road

Pa&o Alto, California 94304

Dear Dr. Lederberg:

Upon my return to Chicago, I would like to thank you once
more for your kind hospitality during my recent visit to
your laboratory.

I particularly enjoyed our interesting dii@ecussions on the
possible significance of perlodic macromolecular structures
derived from specific assemblies of asymmetric units as a
diagnostic criterion of biogenic origin.

I shall try to follow up some of your most stimulating
Suggestions along these lines, and will keep you informed
of further developments.

I am sending under separate cover a reprint of a recent

paper entitled, "New Approaches in Correlative Studies of
Biological Ultrastructure by High-Resolution Electron Microscopy, "
published in the Journal of Royal Microscopical society, which
may be of interest to you in connection with our discussions.

I am looking forward to the pleasvre of seeing you and your
associates again in October and remain with best regards,
Sincerely yours,
bunk £2 Pane hon
H,/FernandeZ-Moran,; M.D., Ph.D.
Professor of Biophysics

HFM/ jr

WrbLoW — TA CNW I

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