as

May 21, 1952

Dr. BE. D. Delamatas
Department of Bacteriology
U. of Pa. Medical School
Philedelphia 4, Pa.

Dear Sd:

The prep. enclosed, made from K-12 a few days ago may interest you; I'd
like your gomment oa ita interpretation. Something went wrong, probably
with the fixation, and the nuclear olsesenta are shrunken down, but the
result is it say be possible to count the unite. I have the immreasion
of a basic ast of three "chromsoms", for there are a lot of cells that
Look aonathing iike: » Unfortunately, there are

& . :

Rev. >t also some others that con't fit "sueh a elaple picture so very well.

i

To mse ea long overdue awxer to scwe of your questions::there fe a little
of dur cytolcgical «wurk in the G3H paper. Until we get a good deal further
along alth cur daterpretations, 2 don't pian to publish much sore, but 7 em
#afinitely gcing along with it in the two obvious dirsctions: looking for the
conjugation (on which we have some leads) amd comparing haploid with diploid,
and maybe later, with triploid (which I think we can get if we take the
trouble), By tho way, our AInterpretatdon of the alides was written for the
CSH as. befcre we knew of your work, and we took special pains not to alter
it, so there could be no question of hindsight. I am morally convinced of
a@itosis cf scurse, but aa oot wo optimistic of owing able to set up a com
prehensive, provebia story with may own material, whish as you pointed out
is hardly the best. What's going on with the genetics of B. megaterium?

Bbvout roprints, I should have sent some out long ago (what little I have
left, that is ) but I was sure you already did have some of them, though I
couldn't find any record. Some are in the mail; if you will let me know whht
else you my have, I'll see what I can do to £111 any gap. Of course I hope
to continue oxchange of anything further.

For some of our vital mleroscopy, it would be very useful to have a vital
stain tag for two parenta to be crossed. Tetrasolium works beautifully, but
the granuke (which I think is a localized deposit, and not at all a etedin of
the chondricsoms itself) does not divide along with the cell, so I can't use
presence/abesnce as a tage.Do you know of another vital stain that can be
distinguished cell. by cell perhaps another tetrazolium in the collection
yougand Mudd have been using, Those I've tried have a reddish cast and can't
be definitely distinguished from one cell to another.

Yours sincerely,

Joshua Lederberg