CALIFORNIA INSTITUTE OF TECHNOLOGY

PASADENA, CALIFORNIA
May 2, 1956

DIVISION OF BIOLOGY

Prof. Joshua Lederberg,
Department of Genetics,
University of Wisconsin,
Madison, Wisconsin

Dear Dr. lederberg,

Enclosed you will find a reprint of the article you wanted,

as well as one of a study we did on the effect of ‘granules! and supernatant fluids
on chorioallantoic membranes. A vrior study on this sort of material was one I

did with Brachet ("xperientia, 5, 235, 199) on the cytalogical effects of treating
the membranes with gramile suspensions. I unfortunately don't have any more reprints
of this. One of Brachet's pupils has published a short note on the effects on
glucose-6—phpsphate in chorioallantoic membranes of treatment with liver microsames
(leClerc, Je, Experientia, i0, 2514+ AlL of this chorioallantoic membrane work stemmed
from a study Brachet and LE did on the effects of injecting embryonic microsomes into
frog eggs and early embryos (Zxperientia, 5, 20, 1919), the results of which were
somewhat inconclusive. I think it micht be added that all these studies suffer from
the somewhat crastic methods used in isolating the particulate fractions. The homog-—
-enates were made in cilute phosnhate buffer, and, as you kmow, there is considerable
evidence that particles sedimented from such homogenates may be, at least in part,
artefacts.

Lost recently, I have been interested in mitochondria curing sea
urchin development, especially with their localization and with fluctuations in
mitochondrial populations during e.rly development. I tried adapting a method used
for counting mitochondria in liver homogenates, but wth what success I'm still not
too certain. However, I think the data give a rough notion of mitochondrial numbers
curing early development, and I enclose a cowey of an MS [I've sent off for publica-

~tione Unfortunately, I con't seem to have copies of all the graphs, so I can send
only Figs. 5 & 6 (mentioned in the text). I would like to have the MS back, but
there's no hurry about it.

Thank you for sending a copy of your review, which I shall read

with creat interest.

Yours sincerely, ,

Mun (@ Ch AWG
John R,. Shaver