ERYTHROMYCIN is a new antibiotic produced by an organism that was originally isolated from a soil sample collected on the island of Panay in the Philippines and identified on the basis of its morphology, cultural characteristics and physiology as a strain of Streptomyces erythreus (Waksman). The production and some of the chemical and biologic characteristics of this antibiotic have been reported by a group of workers from the Lilly Research Laboratories.§ When extracted with suitable reagents from the filtrate of properly grown cultures of the organism, the antibiotic is obtained in crystalline form as a basic compound that is grayish . . .