72 SACCHAROMYCES LESS. 



staining, a small rounded nucleus has been shown to exist 

 near the centre of the cell. 



The cell-wall is so thin that it is difficult to be sure of 

 its presence unless very high powers are employed. It 

 can however be easily demonstrated by staining yeast with 



~bcl' 



FIG. 12. Sacckaromyces cerevisia. 



A, a group of cells under a moderately high power. The scale to 

 the left applies to this figure only. 



B, several cells more highly magnified, showing various stages ot 

 budding, vac, the vacuole. 



C, a single cell with two buds (bd, bd'} still more highly mag- 

 nified : c.w, cell -wall : vac, vacuole. 



D, cells, crushed by pressure : c.iv, the ruptured cell-walls : plsm, 

 the squeezed out protoplasm. 



E, E', starved cells, showing large vacuoles and fat globules (/). 



F, F', formation of spores by fission of the protoplasm of a starved 

 cell : in F the spores are still enclosed in the mother-cell-wall, in F' 

 they are free. 



magenta, and then applying pressure to the cover-glass so as 

 to crush the cells. Under this treatment the cell-walls are 

 burst and appear as crumpled sacs, split in various ways and 

 unstained by the magenta (D, c.w), while the squeezed-out 

 protoplasm is seen in the form of irregular masses (plsm) 

 stained pink by the dye. 



