April 17, 1961

Dr. Phillip Morrison
Department of Physics
Cornel] University
ithaca, New York

Dear Phil:

ie
Jaffe has more certain Information on the surface envi ronment / Pyar
than 1! do. 6

But there is some merit to the view that moisture [s the
limiting ecological factor, and 1 would share the expectation that
an organism large enough to shield Itself might be preferred tn the
exposed environment. However, there must also be saprophytes to
complete the carbon cycle and { would still propose these as the
most ublquitous types, as they are on earth. If these could evolve
efficient means for accumulating Ho0 against a concentration gradient,
(as terrestrial cells do to some extent for water, and sometimes very
spectacularly for, say, Varradium) they might have an active rather
than passive barrier to the desiccant equi librium.

More power to him If he can design the calorimeter. But
how will he distingulsh photosynthesis from other photochemically
driven reactions?

Yours sincerely,

Joshua Lederberg
Professor of Genetics

je