64 BOTANY. 



cell sap. No nucleus is visible in the living cell, but it has been shown 



that a nucleus is present. 



If growth is active, many of the cells will be seen dividing. The 

 process is somewhat different from or- 

 dinary fission and is called budding 

 (Fig. 37, .B). A small protuberance ap- 

 pears at the bud or at the side of the cell, 

 and enlarges rapidly, assuming the form 

 of the mother cell, from which it becomes 

 completely separated by the constriction 

 of the base, and may fall off at once, or, 

 as is more frequently the case, may re- 

 main attached for a time, giving rise itself 



to other buds ' so that not "^frequently 

 showing the process of bud- groups of half a dozen or more cells are 

 ding, x 750. met with 



That the yeast cells are the principal agents of alcoholic 

 fermentation may be shown in much the same way that bac- 

 teria are shown to cause ordinary decomposition. Liquids 

 from which they are excluded will remain unfermented for 

 an indefinite time. 



There has been much controversy as to the systematic posi- 

 tion of the yeast fungi, which has not yet been satisfactorily 

 settled, the question being whether they are to be regarded 

 as independent plants or only one stage in the life history of 

 some higher fungi (possibly the /Smuts), which through culti- 

 vation have lost the power of developing further. 



CLASS I. THE SMUTS (Ustillaginece) . 



The smuts are common and often very destructive parasitic 

 fungi, living entirely within the tissues of the higher plants. 

 Owing to this, as well as to the excessively small spores and 

 difficulty in germinating them, the plants are very difficult of 

 study, except in a general way, and we will content ourselves 

 with a glance at one of the common forms, the corn smut 



