When ascites fluid was added to infusion agar, the colonies on the slants became larger and more moist and, when numerous, formed a confluent mucoid growth. This property of ascites fluid was then utilized in the preparation of poured blood agar plates and has furnished us with a medium which brings out strikingly characteristic colonies of Streptococcus epidemicus.To meat infusion agar (2 per cent), pu 7.2, defibrinated human blood and ascites fluid are added in proportions of 0.5 cc. of blood and 2 cc. of ascites fluid to 10 cc. of agar. This mixture is inoculated with material under study and poured into petri dishes. The best results are obtained when one or two dilutions are made and colonies appear discrete and not too crowded.Ascites fluid, specific gravity from 1.010 to 1.016, from five