Research Bacteriology -
Bldg. 54 - Rm. 16

VETERANS ADMINISTRATION

cecceeeee HOS PITA L.....-.
Hines, Illinois

 

YOUR FILE REFERENCE:

September 19, 1952 IN REPLY REFER TO:

Dr. Joshua Lederberg
Department of Genetics
College of Agriculture
Madison 6, Wisconsin

Dear Dr. Lederberg:
We have used no very precise methods in preparing the

McLeod's synthetic medium except for using reagents of highest purity
for our work with MN®Q. ‘The composition of the medium was as follows:

Ammonium sulfate 4.72 grams
Asparagine 2.0 7
Sodium chloride 5.0 "
Teo. ( , 2.0 "
PO,
mie 4 5 100, mle
Va OH (N) 16.4 ml. (or to pH 7.8)
i

0.6% solutions of MgCl,, Fe Cl, and Ca Cl, were freshly pre-
pared separately, then mixed, arid 1.0 mi of the mixture was added to
the mediun.

Distilled water 1000 ml.

Chemicals were weighed only roughly on a triple beam balance
accurate to 0.01 gram, even for the u/s KH, PO, solution.

2°74
pH should be about 7.8 before autoclaving, using the amount
of NaOH designated; if not, NaOH was added to this point.
pH after autoclaving at 12 lbs. for 20 minutes, 7.6.

Medium was distributed by hand-pipetting with 25 ml measuring
pipettes in 24.5 ml. amounts into 8" x 1" test tubes.-

Difco nutrient agar, (B 69), was used for streaking oultures
and for slants.

I trust that your efforts will meet with more success this time.

s org Ye 0.6.0.0.
es E A. COLWELL, Ph. D.

HARLO
An inquiry by or concerning an ex-service man or woman shoul it possible, give veteran's name and file number, whether
C, XC, K, N, or V. If such file number is unknown, service or serial number should be given.