THE FUNGI. 149 



due to the fact that the outer coating of the cell wall is 

 mucilaginous, frequently gives rise to chains or groups of 

 cells. Draw a single cell and groups of cells showing 

 buds. 



2. Sow thin layers of yeast that is in the active bud- 

 ding condition on slabs of plaster of Paris or on freshly 

 cut surfaces of potato or turnip. The surface portions of 

 a cultivation of yeast obtained from a brewery are best 

 for this observation. Keep under bell jars, adding dis- 

 tilled water to the containing dish from time to time to 

 prevent the yeast from drying up. It is best to prepare 

 a number of these cultivations, as bacterial and fungoid 

 growths are likely to interfere. Examine mounts of the 

 yeast from the surface daily, after about a week, until 

 the contents of some of the cells are seen to have under- 

 gone division into two or four parts. The yeast cells are 

 starved, the vacuoles become larger and more numerous, 

 and, as a last effort to preserve life, the protoplasm divides 

 into what are virtually resting spores. These divided 

 cell contents indicate another method of reproduction. 

 They are known as ascospores or sac spores. They are 

 called sac spores because they are contained within the 

 wall of the mother cell as in a sac. Draw a typical cell. 



3. Make a mount of actively growing yeast. Observe 

 the vacuoles clear spaces empty of protoplasm in the 

 central part of many of the cells. Between the vacuoles 

 and the surfaces of the cells observe the protoplasm, 

 which is quite clear in many of the cells ; in others, it 

 presents a granular appearance, due to the presence of 

 minute particles of oil and granules of proteinaceous 

 matter. 



4. Study the cell wall. Press firmly on the cover 

 glass, and thus burst some of the cells. Observe the 

 colorless cell walls left empty of their contents. Run a 

 drop of magenta under the cover glass. The cell wall is 



