STRUCTURE OF YEASTS 



79 



in size until finally it may be as large as the original plant 

 (Fig- 33» ^)- Usually by this time, if the growth is vigor- 

 ous, there may have appeared a second bud. The latter 

 sometimes arises from the side of the first cell and some- 

 times from the side of the first bud, giving an appearance 

 such as is shown at Fig. 33, c. This budding continues, 

 the little buds appearing one after the other, until there 

 are produced irregular-shaped groups like those shown at 

 Fig- 33) ^- For a considerable time the cells in these 

 groups remain attached to each other, so that a little of 

 the sediment from 

 a fermenting liquid 

 will appear under 

 the microscope as 

 shown in Fig. 33, d. 

 After a while, how- 

 ever, the different 

 cells drop apart 

 and may go into 

 a resting stage, each cell remaining by itself. These 

 cells are capable of growth and development, either imme- 

 diately or subsequently, when again placed in a solution 

 which furnishes them food. This method of multipli- 

 cation, which is distinctly characteristic of yeasts and 

 separates them sharply from bacteria, the next group of 

 plants to be studied, is known as budding. The yeast 

 plants are therefore sometimes called the budding fungi. 



The Spore-bearing State. Under some conditions yeast 

 plants produce a different kind of reproductive body known 

 as spores. If a lot of yeast is placed where it has mois- 

 ture but insufficient food, it does not grow by the normal 



Fig. 33. Growing yeast cells, showing method 

 of budding and forming groups of cells. 



