22 AGRICULTURAL BACTERIOLOGY. 



related to the yeasts, and only a little more distantly related to 

 the molds. Moreover, in some of the phenomena which we 

 shall find it necessary to notice in later pages, the yeasts and 

 molds play a part equally important with the bacteria, while in 

 others alcoholic fermentations the function of the yeasts is 

 the greater. But, with occasional reference to these closely 

 related plants, we can confine our attention almost wholly to 

 the Bacteria proper. 



In a work of this nature any extended consideration of the 

 classification of bacteria is needless. It is only the micros- 

 copist who can make use of such a classification. The agri- 

 culturist is interested in bacteria solely for their functions and 

 not at all for their scientific relations. For this reason we may 

 consider the problem of the microscopic structure and relation 

 of these plants with great brevity, selecting for consideration 

 only such salient features as are of most importance in un- 

 derstanding bacteriological terms used in literature. For a 

 fuller consideration of bacteria and their methods of culture 

 reference must be had to some of the numerous books now 

 available for this purpose (see list of references). 



I. CLASSIFICATION OF FUNGI. 



Bacteria belong to the group of colorless plants called 

 Fungi. All of the group of Fungi are of great significance 

 to agriculture, performing important functions based upon 

 their power of decomposing organic substances and using 

 them as food. Unlike the ordinary green plants, they are 

 commonly unable to live upon mineral foods and are in conse- 

 quence extremely important agents in disposing of the great 

 quantities of dead organic matter in nature. These Fungi 

 may be for our purpose conveniently divided into three di- 

 visions : 



I. Higher Fungi. Under this head we may group together 

 a large variety of colorless plants comprising several large 



