May 13, 1956 —

Dr. John R. Shaver

Division of Biology

California Institute of Technology
Readena 4, California

Dear Dr, Shavers

Thank you for sending me the manuscript of your paper on mito~
chondria in development. We sursly need as many more quantitative
studies as can be devised along these lines. One possible teehnical
suggestion: to homogenize your cells by injecting from the syringe
under oil, or with an antifoaming agent, to reduce losses fron foaming.
Does the number of times the procedure is repeated affect the yield?

As you may gather from my review, I am rather sceptical of the eyi-
dence that mitochondbia are genetic plasmids, but the direct approach
of your earlier experiments seems the only likely one, LeClere'!s experi-
ments are entirely unconvincing, for the reasons cited in Brachet's dis-
cussions of your experiments (e.g. in the Soc Exp Biol Symp 6), and be-
cause the effects are so small that the stability of the ahsolute enzyme
neasurement can be questioned, However, mitochondria from different
organs appear to be enzymatically differentiated, and this misht bea
basis for experiments with specificity controls,

The last time we talked together if I remember rightly was at tic
Woods Hole almost 10 years agozis there any likelihood of seeing vou there
again this summer?

Please give my regatds to Dr. Tyler, and if you see him especially
to Stevie.

Yours sincebely,

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