36 FUNGI 



Bacteria in the form of rounded bodies are called Cocci 

 (singular, Coccus). Those in the form of rods are known as 

 Bacilli (singular, Bacillus). Those having the form of a 

 curved rod are classed as Spirilla (singular, Spirillum). 



Physiology. Physiologically bacteria are divided into the 

 following classes: 



I. Holophytic. 

 II. Saprophytic. 

 III. Parasitic. 



I. Holophytic bacteria can manufacture organic compounds 

 from carbon dioxide and water in a manner similar to that 

 of chlorophyll-bearing plants. This peculiar function is 

 possessed by many nitrogen bacteria. 



II. Saprophytic bacteria, derive their food from dead 

 organic matter. The chief classes of Saprophytic bacteria 

 are the following: 



1. Nitrifying bacteria. 



2. Denitrifying bacteria. 



3. Fermentative bacteria. 



4. Cheese bacteria. 



5. Putrefactive bacteria. 



1. Nitrifying Bacteria. One group of bacteria occurring 

 in the soil absorbs atmospheric nitrogen and combines it 

 with the chemical elements in solution in the soil water to 

 make nitrates, which is the form of nitrogen suitable for 

 plant food. 



2. Denitrifying Bacteria. The reduction of protoplasm 

 to nitrates, of nitrates to nitrites, of nitrites to nitrogen gas 

 is accomplished by several different groups of denitrifying 

 bacteria. These bacteria complete the nitrogen cycle by 

 returning nitrogen to the air from which it was taken by the 

 nitrifying bacteria. 



