Dependence of the kappa particles of stock 7 of Paramecium aurelia on a single gene.

K A P P A and several other types of symbiotic particles are found in various stocks of Paramecium aurelia; their characteristics have been reviewed extensively by SONNEBORN (1959) and more recently by PREER (1967). Many of these symbiotic particles enable the paramecium containing them to kill paramecia that lack them and to be themselves resistant to the killing activity of animals containing the same type of symbiotic particle. Several of these symbionts are known to be lost when the genotype of the host paramecium changes with respect to certain genes; these are the kappa particles of stock 51 of syngen 4 (SONNEBORN 1943), the mu particles of stock 540 of syngen 1 (GIBSON and BEALE 1961) and of stock 138 of syngen 8 (SIEGEL 1953), and the lambda particles of stock 299 of syngen 4 (SCHNELLER, SONNEBORN and MUELLER 1959). This paper deals with the genic dependence of the kappa particles of stock 7 of syngen 2. The results of this study support the conclusion, slowly emerging in recent years, that each of the various types of symbiotic particles in Paramecium is maintained only in the presence of one or two specific alleles of chromosomal genes.