Serotypes and Immobilization Antigens in Paramecium caudatum*

SYNOPSIS. Some of the serotypes in Paramecium caudatum are described in this paper. Immobilization antigens of P. caudatum have been obtained by extracting paramecia in a dilute salt solution containing 15% alcohol. Immobilization antigen F from stock 162 has been isolated and has a sedimentation coefficient of 9.3 Svedbergs, diffusion coefficient of 2.3 × 10^-7 cm/sec, and molecular weight of approximately 340,000.