THALLOPHYTES 



45 



method of reproduction is by means of vegetative multi- 

 plication, but this multiplication proceeds with such remark- 

 able rapidity that a single cell may give rise to millions of 

 cells in twenty-four hours. Some of the important work 

 done by bacteria may be outlined as follows. 



Some bacteria attack dead bodies of plants and animals, 

 or organic material produced by plants and animals result- 



FIG. 25. Diagram of Mucor, showing the profusely branching mycelium and three 

 sporophores, one of which bears a sporangium. After ZOPF. 



ing in what is called putrefaction or fermentation (Fig. 24, 

 A and B). All of this work is of large service, but special use 

 is made of certain of the fermentations, as already mentioned. 

 Other bacteria attack living plants and animals, producing 

 various diseases, which are regarded as important so far as 

 they affect our cultivated plants, our domesticated animals, 

 and ourselves. Many of the common and most dangerous 

 diseases of the human race, such as typhoid fever (Fig. 23, F), 



