24 AGRICULTURAL AND INDUSTRIAL BACTERIOLOGY 



Conidia Formation. — Certain of the filamentous or so- 

 called higher bacteria sometimes divide by numerous cross 

 walls and split into small cells which function as spores. 

 These are termed conidia. They are probably not com- 

 monly found among the cocci, bacilli, or spirilla. 



Classification op Bacteria 



The true bacteria belong to the class ScJiizomycetes. 

 They may be characterized as minute, one-celled, chloro- 

 phyll free, colorless, rarely violet-red or pigmented plants, 

 which typically multiply by dividing in one, two, or three 

 directions of space. The cells thus formed are usually 

 spherical, cylindrical, comma-shaped, spiral or filamentous, 

 and are often united into filamentous, flat, or cubical aggre- 

 gates. Filamentous species are often surrounded by a com- 

 mon sheath. The cell plasma is generally homogenous with- 

 out a definite nucleus. Sexual reproduction is absent. In 

 some species reproductive bodies are produced, either endo- 

 spores or conidia. The cells in some species are motile by 

 means of flagella. 



The class Schizomycetes may be subdivided into six dis- 

 tinct orders. Of these, four are not of great agricultural 

 significance. Two, however, are of sufficient interest to 

 require discussion. The four orders not further discussed 

 are the slime bacteria (belonging to the order Myxobac- 

 teriales), the sulphur bacteria (belonging to the order 

 Thiobacteriales,) the iron bacteria (belonging to the order 

 Chlamydobacteriales) and the spirochetes [Spirochaetales) . 

 The two orders of agricultural significance are the filamen- 

 tous or branching bacteria (belonging to the order Actino- 

 mycetales) and the true bacteria (order E uh act er idles). 



Orders in botany are divided into families, families into 

 genera, and genera into species. Each kind of bacterium 

 constitutes a species. The related species are grouped 

 together into genera, and related genera into families. For 



