Somatic chromosomal reduction in yeast

Abstract

An abnormal type of segregation by which endopolypoid cells give rise to buds having the normal diploid complement of two chromosomes, is described in five-day old fermenting liquid cultures. Microphotographs are presented to show that the above phenomenon is not confined to liquid cultures alone but occurs also in endopolyploid cells from agar slants. It is suggested that the mode of segregation described above is a type of somatic reduction in chromosome number by which the yeast strain can survive in an unfavourable environment wherein the population consists predominantly of endopolyploid cells of varying complexity.