Abstract
Determination of the ploidy of Saccharomyces cerevisiae 0209, 0635 and 0637, and Candida robusta 0718 and 0735 were performed by the estimations of the dry weight per cell and of cell size and also by the observation of the survivals after the X ray irradiation.
Results obtained were as follows :
1. S. cerevisiae 0209 was seemed to be diploid strain, and S. cerevisiae 0635 and 0637 were in the haploid state. C. robusta 0718 and 0735 were seemed to be triploid strains of S. cerevisiae. 2. From the view point of the ploidy, chromosomal counts previously discribed must increase parallely to the ploidy increases. But chromosomal counts of the strains were almost the same independently of their ploidy.
3. The author considered that the stained chromosomes were not true forms of the nuclear material. Therefore, the author venture to propose together with the previous report that the nuclear material in the living state of the yeast cell exists perivacuolarily.
