Abstract
The present study deals with the determination and inheritance of mating type of Paramecium polycaryum collected from several parts of Sapporo City and of some other cities in Hokkaido. The determination of mating type was made with 245 clones established in our laboratory during a period from March of 1959 to April of 1961, and it was found that all of these clones, except four which failed to study, belonged to one syngen and two mating types, I and II (for detail, refer to Table 1). Based on the facts that no mating reaction has been observed in this species, and that only one syngen has been found in this study, it seems probable that this species has been in state of low differentiation, so far as the breeding system is concerned. Conclusive statements should be made, however, on the basis of the data from further survey in future.
In the light of the results of the experiments on the inheritance of mating type, it was concluded that this species was characterized by clonal inheritance (Table 2).
