The yeast nucleus

Abstract

The disagreements on the question whether the nucleus of yeast is an organelle unrelated to the vacuole or whether it is the vacoule itself (Pictographic Summary I, 1844-1956) is only a corollary to the limitations of fixation and staining procedures carried out on cells in which the former was invisible. A reconciliation is possible if investigations are confined to cells in which both the organelles are visible. The extra-vacuolar nucleus has a conventional vesicular structure with a nuclear membrane, chromocenters and nucleolar equivalents. The vacuole, which has a limiting membrane in older cells, is Feulgen negative and segregates neutral red in living cells. It is therefore a cytoplasmic inclusion. A strict comparison of living with stained preparations is presented in Pictographic Summary II, 1956.