December ©, 1953

Miss Ethelyn R. Lively
Department of Bacteriology
University of Tllinois
Urbana, Tllinois

Dear Ethelyn:

Thank you very much for the resume that you sent up with Seymour. I+ was
quite clear and very helpful indeed in enabling me to understand the details of
your experiments. Unfortunately, as you suggest, none of them is entirely ‘e-
cisive to the crucial point immediately at issue now, especially as there is no
explicit statement concerning the streptomycin character of some of the single-
cell isolates. I was able to find the vials i: which you had left the three
isolates recorded as having been stored but unfortunately they were no longer
viable. At any rate, it was not these cultures which were lixely to have been
of the greatest immediate use.

During the past few weeks I have been develoning an elternative technique
for the isolation of single-cell clones for this study. There is nothing
startlingly new about it but you may be interested in how jt is hendled. It
is just a matter of placing small droplets of diluted om ltures in order on a
glass slide which has previously been coated with a layer of mineral oil. (Are
you using an 011 chamber technicue et the present time?) The of], of course,
prevents the evaporation of the droplets end nermits them to be eveminec at
leisure for the mumber of cells which they cortain. Those droplets containing
precisely one cell sre marked, additions] broth is added to them, arr! these
larger drops are then incubated until the cell has given rise to a substantial
clone. This can then readily be pieked under the dissecting microscope with a
small capillary pipette. As you see, the technicve reovtres no micromanipulation
and does in fact permit the rather facile isolation of large mumbers of single
cells. I have not yet, however, been lucky enourh to obtain a zyrote cell in my
manipulations but this is probably only a metter of time.

A Dr. S. Rubbo has just core to visit the laboratory for a short neriod of
time and et least while ne is here we my be dcing be a little bit of work on
yeast ourselves. I do hope that you will sometime be able to realize my invit-
ation to go over and re-sumezrize some of your older accumlated data at sone
future visit to Madison.

Meamuhile, best wishes and

Yours sincerely,

Josima Lederberg