SAC FUNGI IN PARTICULAR 



135 



much can be said that the wall consists of a carbohydrate, probably 

 some isomer of cellulose. Lining the inner surface of the cell wall is a 

 layer of protoplasm which may be called the ectoplasm, which probably 

 serves as an osmotic membrane. The cytoplasm fills the rest of the cell 

 with the exception of spaces occupied by the vacuoles of glycogen, 

 nuclear vacuoles, oil globules, the nucleus and nuclear granules. The 

 glycogen is gradually used up as it probably serves as reserve food, 

 the same as starch in the higher plants. These glycogen vacuoles 

 generally coalesce until one large vacuole may almost fill the cell, 



6 7 8 



Fig. 43. Fig- 44. 



Fig. 43. — Yeast cell, Saccharomyces cererisia. (After Marshall.) 

 Pig. 44. — Yeast, Saccharomyces cercrisuc. i-io. Young cells with nucleus, 

 showing its stmctuie; 6-8, division of nucleus; 11— 13, cells after twenty-four hours' 

 fermentation with laxse glycogenic vacuole filled with lightly colored grains. (After 

 MarshaU, Microbiology, Second edilion. p. 62.) 



the cytoplasm and nuclear bodies being pressed against the cell wall 

 and forming a thin protoplasmic lining to the inner cell wall surface. 

 Wager* in 1898 demonstrated the nuclear apparatus in a number of 

 yeast species. The nuclear apparatus consists in the earliest stages of 

 fermentation of a nucleolus in dose touch with a vacuole (Fig. 44, No. 4) 

 which includes a granular chromatin network suggesting a similar struc- 

 ture in the higher plants. The vacuole may disappear and then the 

 chromatin granules are scattered through the protoplasm, or are gathered 

 around the nucleolus, which is present in all of the cells, as a perfectly 

 homogeneous body. Numerous chromatin vacuoles are often found 



* Wager, Harold: The Nudeus of the Yeast Plant, The Annals of Botany 

 xii: 400-539- 



