September 6, 1961

Mitltpore Filter Corporation
Bedford
Massachusetts

Gent lemen:

| hope that this letter may strike the fortunate note that you

have already had oceasion to survey the literature on the cultivation
of bacteria on cellophane or other plastic films other than millipore
membranes. We have been doing some work lately where the results of a
literature search In this area would be most useful to uc and {| am
witing to you to ask whether you could offer the courtesy that might
save us many man hours of work. We are, of course, indeLted to you
for many past favors and for furnishing biblfographles on your own
materltals.

It may be a point of some Interest to you that the extent of
development of bacterlal colontes on miltipore membrane filters can be
greatly stimulated by impregnating the filters with egar before laying
the fiiters on the nutrient base. 1! would assume that this effect ts
based on the superior water-"'buffering'’’ properties of the ager gei
@s compared to the membrane material. Whether this finding would be of
any use In the more typical application of the filters | am not sure
although | can visualize that It would not be too difficult to conduct
this impregnation either after the tested samples ave been filtered
through the clean membranes.

Yours stncersely,
Joshua Lederberg
Professor of Genetics
P.S. . San you furnish type WH microweb fliters In clretes of dlaneter

80-83 mn? (for use In plastic petri dishes). If so, please quote for
quantities of 10 and 100.

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