In 1919 and 1920, Eberson1 reported a medium for the preservation of stock strains of meningococci. By the use of this medium he was able to keep strains of this organism viable for five months. My purpose in this note is to report the successful use of this medium for periods longer than five months, the simplification of the medium, and the preservation of strains of gonococcus, pneumococcus, B. pertussis and B. influenzae.
Eberson used a yeast semisolid agar medium, the essential details of which are as follows: A suspension of 10 gm. of bakers' yeast in 100 c.c. of water was steamed at 100 C. for two hours, clarified at the end of that time with dialyzed iron (Merck), and then filtered through a Berkefeld filter. One part of the yeast extract was then added to one part of agar mixture. The agar medium contained 1 per cent.