Induction of meiosis in yeast is a complex process starting during the period of premeiotic mitoses. Enlargement of the nucleus is the earliest sign of the actual onset of meiosis. Parallel with this development is an increase of about 10% in the protein content of the cell. Somewhat later there is a sharp rise in cell mass and cell volume. There is only one period of high metabolic activity during sporogenesis and this occurs early during the process.