DEVELOPMENT OF PLANTS 



-Mv 



freed by the decay of the ascus and when concHiions are favcjrable, 

 grow into the characteristic yeast cells, as shown in Fig. i6i, F. 



(a) Fermentatio7i.- — These microscopic plants must be num- 

 bered among those plants that are of the greatest economic value. 

 Their importance is due to the fact that they decompose sugars 

 upon which they feed into COo and alcohol, a change called fer- 

 mentation. The extensive brewing and distilling industries all 



Fig. i6i. The yeast plant, Saccharomyccs: A, single plain, ly, yuxui 

 producing three buds. C, section of two plants showing buds and nuclear 

 division. Z), chain of plants due to rapid budding and growth. E, forma- 

 tion of ascospores. F, germination of an ascosporc and the formation of 

 new plants by budding, — After Wager. 



over the world are dependent upon the growth and peculiar action 

 of these microscopic plants. When yeast plants are i>laced in 

 solutions containing sugar in the form of molasses or prepara- 

 tions of rye, corn, barley, potatoes, etc., and slightly warmed, the 

 growth of the yeast produces a vigorous fermentation. CarlKjn 

 dioxide rises to the surface, forming a froth)' scum while the alco- 

 hol accumulates in the fluid. Beers and ales are fermented bever- 

 ages of this nature, while whiskies, brandies, alcohol, etc., are 

 obtained from the fermented mass by removing a part of the 

 water by distillation. Wines and cider are weak alcoholic bev- 



